podman-run - Online Linux Manual Page

Section : 1

NAME

podman-run - Run a command in a new container

SYNOPSIS

podman run

[

options

]

image

[

command

[

arg

...]

]

podman container run

[

options

]

image

[

command

[

arg

...]

]

DESCRIPTION

Run a process in a new container. podman run

starts a process with its own file system, its own networking, and its own isolated process tree. The

image

which starts the process may define defaults related to the process that will be run in the container, the networking to expose, and more, but

podman run

gives final control to the operator or administrator who starts the container from the image. For that reason

podman run

has more options than any other Podman command.

If the image

is not already loaded then

podman run

will pull the

image

, and all image dependencies, from the repository in the same way running

podman pull

image

, before it starts the container from that image.

Several files will be automatically created within the container. These include /etc/hosts

/etc/hostname

, and

/etc/resolv.conf

to manage networking. These will be based on the host's version of the files, though they can be customized with options (for example,

--dns

will override the host's DNS servers in the created

resolv.conf

). Additionally, a container environment file is created in each container to indicate to programs they are running in a container. This file is located at

/run/.containerenv

. When using the --privileged flag the .containerenv contains name/value pairs indicating the container engine version, whether the engine is running in rootless mode, the container name and id, as well as the image name and id that the container is based on.

When running from a user defined network namespace, the /etc/netns/NSNAME/resolv.conf

will be used if it exists, otherwise

/etc/resolv.conf

will be used.

Default settings are defined in

containers.conf

. Most settings for remote connections use the servers containers.conf, except when documented in man pages.

IMAGE

The image is specified using transport:path format. If no transport is specified, the

docker

(container registry) transport will be used by default. For remote Podman, including Mac and Windows (excluding WSL2) machines,

docker

is the only allowed transport.

dir:

path

An existing local directory

path

storing the manifest, layer tarballs and signatures as individual files. This is a non-standardized format, primarily useful for debugging or noninvasive container inspection.

$ podman save --format docker-dir fedora -o /tmp/fedora $ podman run dir:/tmp/fedora echo hello

docker://

docker-reference

(Default)
An image reference stored in a remote container image registry. Example: "quay.io/podman/stable:latest". The reference can include a path to a specific registry; if it does not, the registries listed in registries.conf will be queried to find a matching image. By default, credentials from

podman login

(stored at $XDG_RUNTIME_DIR/containers/auth.json by default) will be used to authenticate; otherwise it falls back to using credentials in $HOME/.docker/config.json.

$ podman run registry.fedoraproject.org/fedora:latest echo hello

docker-archive:

path

[

docker-reference

] An image stored in the

docker save

formatted file.

docker-reference

is only used when creating such a file, and it must not contain a digest.

$ podman save --format docker-archive fedora -o /tmp/fedora $ podman run docker-archive:/tmp/fedora echo hello

docker-daemon:

docker-reference

An image in

docker-reference

format stored in the docker daemon internal storage. The

docker-reference

can also be an image ID (docker-daemon:algo:digest).

$ sudo docker pull fedora $ sudo podman run docker-daemon:docker.io/library/fedora echo hello

oci-archive:

path

tag

An image in a directory compliant with the "Open Container Image Layout Specification" at the specified

path

and specified with a

tag

$ podman save --format oci-archive fedora -o /tmp/fedora $ podman run oci-archive:/tmp/fedora echo hello

OPTIONS

--add-host

host:ip

Add a custom host-to-IP mapping (host:ip)

Add a line to /etc/hosts. The format is hostname:ip. The --add-host

option can be set multiple times. Conflicts with the

--no-hosts

option.

--annotation

key=value

Add an annotation to the container. This option can be set multiple times.

--arch

ARCH

Override the architecture, defaults to hosts, of the image to be pulled. For example,

arm

. Unless overridden, subsequent lookups of the same image in the local storage will match this architecture, regardless of the host.

--attach

-a

stdin

stdout

stderr

Attach to STDIN, STDOUT or STDERR.

In foreground mode (the default when -d

is not specified),

podman run

can start the process in the container and attach the console to the process's standard input, output, and error. It can even pretend to be a TTY (this is what most command-line executables expect) and pass along signals. The

-a

option can be set for each of

stdin

stdout

, and

stderr

--authfile

path

Path of the authentication file. Default is

${XDG_RUNTIME_DIR}/containers/auth.json

, which is set using

podman login

. If the authorization state is not found there,

$HOME/.docker/config.json

is checked, which is set using

docker login

Note: There is also the option to override the default path of the authentication file by setting the

REGISTRY_AUTH_FILE

environment variable. This can be done with

export REGISTRY_AUTH_FILE=

path

--blkio-weight

weight

Block IO relative weight. The weight

is a value between

and

1000

This option is not supported on cgroups V1 rootless systems.

--blkio-weight-device

device:weight

Block IO relative device weight.

--cap-add

capability

Add Linux capabilities.

--cap-drop

capability

Drop Linux capabilities.

--cgroup-conf

KEY=VALUE

When running on cgroup v2, specify the cgroup file to write to and its value. For example --cgroup-conf=memory.high=1073741824

sets the memory.high limit to 1GB.

--cgroup-parent

path

Path to cgroups under which the cgroup for the container will be created. If the path is not absolute, the path is considered to be relative to the cgroups path of the init process. Cgroups will be created if they do not already exist.

--cgroupns

mode

Set the cgroup namespace mode for the container.

•

host

: use the host's cgroup namespace inside the container.

•

container:

: join the namespace of the specified container.

•

private

: create a new cgroup namespace.

•

ns:

path

: join the namespace at the specified path.

If the host uses cgroups v1, the default is set to host

. On cgroups v2, the default is

private

--cgroups

how

Determines whether the container will create CGroups.

Default is enabled

The enabled

option will create a new cgroup under the cgroup-parent. The

disabled

option will force the container to not create CGroups, and thus conflicts with CGroup options (

--cgroupns

and

--cgroup-parent

). The

no-conmon

option disables a new CGroup only for the

conmon

process. The

split

option splits the current CGroup in two sub-cgroups: one for conmon and one for the container payload. It is not possible to set

--cgroup-parent

with

split

--chrootdirs

path

Path to a directory inside the container that should be treated as a

chroot

directory. Any Podman managed file (e.g., /etc/resolv.conf, /etc/hosts, etc/hostname) that is mounted into the root directory will be mounted into that location as well. Multiple directories should be separated with a comma.

--cidfile

file

Write the container ID to file

. The file will be removed along with the container.

--conmon-pidfile

file

Write the pid of the conmon

process to a file. As

conmon

runs in a separate process than Podman, this is necessary when using systemd to restart Podman containers. (This option is not available with the remote Podman client, including Mac and Windows (excluding WSL2) machines)

--cpu-period

limit

Set the CPU period for the Completely Fair Scheduler (CFS), which is a duration in microseconds. Once the container's CPU quota is used up, it will not be scheduled to run until the current period ends. Defaults to 100000 microseconds.

On some systems, changing the resource limits may not be allowed for non-root users. For more details, see https://github.com/containers/podman/blob/main/troubleshooting.md#26-running-containers-with-resource-limits-fails-with-a-permissions-error

This option is not supported on cgroups V1 rootless systems.

--cpu-quota

limit

Limit the CPU Completely Fair Scheduler (CFS) quota.

Limit the container's CPU usage. By default, containers run with the full CPU resource. The limit is a number in microseconds. If a number is provided, the container will be allowed to use that much CPU time until the CPU period ends (controllable via --cpu-period

This option is not supported on cgroups V1 rootless systems.

--cpu-rt-period

microseconds

Limit the CPU real-time period in microseconds.

Limit the container's Real Time CPU usage. This option tells the kernel to restrict the container's Real Time CPU usage to the period specified.

This option is only supported on cgroups V1 rootful systems.

--cpu-rt-runtime

microseconds

Limit the CPU real-time runtime in microseconds.

Limit the containers Real Time CPU usage. This option tells the kernel to limit the amount of time in a given CPU period Real Time tasks may consume. Ex: Period of 1,000,000us and Runtime of 950,000us means that this container could consume 95% of available CPU and leave the remaining 5% to normal priority tasks.

The sum of all runtimes across containers cannot exceed the amount allotted to the parent cgroup.

This option is only supported on cgroups V1 rootful systems.

--cpu-shares

-c

CPU shares (relative weight).

By default, all containers get the same proportion of CPU cycles. This proportion can be modified by changing the container's CPU share weighting relative to the combined weight of all the running containers. Default weight is 1024

The proportion will only apply when CPU-intensive processes are running. When tasks in one container are idle, other containers can use the left-over CPU time. The actual amount of CPU time will vary depending on the number of containers running on the system.

For example, consider three containers, one has a cpu-share of 1024 and two others have a cpu-share setting of 512. When processes in all three containers attempt to use 100% of CPU, the first container would receive 50% of the total CPU time. If a fourth container is added with a cpu-share of 1024, the first container only gets 33% of the CPU. The remaining containers receive 16.5%, 16.5% and 33% of the CPU.

On a multi-core system, the shares of CPU time are distributed over all CPU cores. Even if a container is limited to less than 100% of CPU time, it can use 100% of each individual CPU core.

For example, consider a system with more than three cores. If the container C0

is started with

--cpu-shares=512

running one process, and another container

with

--cpu-shares=1024

running two processes, this can result in the following division of CPU shares:

PID	container	CPU	CPU share
100	C0	0	100% of CPU0
101	C1	1	100% of CPU1
102	C1	2	100% of CPU2

This option is not supported on cgroups V1 rootless systems.

--cpus

number

Number of CPUs. The default is 0.0

which means no limit. This is shorthand for

--cpu-period

and

--cpu-quota

, therefore the option cannot be specified with

--cpu-period

--cpu-quota

On some systems, changing the CPU limits may not be allowed for non-root users. For more details, see https://github.com/containers/podman/blob/main/troubleshooting.md#26-running-containers-with-resource-limits-fails-with-a-permissions-error

This option is not supported on cgroups V1 rootless systems.

--cpuset-cpus

number

CPUs in which to allow execution. Can be specified as a comma-separated list (e.g. 0,1

), as a range (e.g.

0-3

), or any combination thereof (e.g.

0-3,7,11-15

This option is not supported on cgroups V1 rootless systems.

--cpuset-mems

nodes

Memory nodes (MEMs) in which to allow execution (0-3, 0,1). Only effective on NUMA systems.

If there are four memory nodes on the system (0-3), use --cpuset-mems=0,1

then processes in the container will only use memory from the first two memory nodes.

This option is not supported on cgroups V1 rootless systems.

--decryption-key

key[:passphrase]

The [key[:passphrase]] to be used for decryption of images. Key can point to keys and/or certificates. Decryption will be tried with all keys. If the key is protected by a passphrase, it is required to be passed in the argument and omitted otherwise.

--detach

-d

Detached mode: run the container in the background and print the new container ID. The default is false

At any time run podman ps

in the other shell to view a list of the running containers. Reattach to a detached container with

podman attach

command.

When attached via tty mode, detach from the container (and leave it running) using a configurable key sequence. The default sequence is

ctrl-p,ctrl-q

. Specify the key sequence using the

--detach-keys

option, or configure it in the

containers.conf

file: see

containers.conf(5)

for more information.

--detach-keys

sequence

Specify the key sequence for detaching a container. Format is a single character

[a-Z]

or one or more

ctrl-<value>

characters where

<value>

is one of:

a-z

@

^

[

,

_

. Specifying "" will disable this feature. The default is

ctrl-p,ctrl-q

This option can also be set in containers.conf(5) file.

--device

host-device[:container-device][:permissions]

Add a host device to the container. Optional permissions

parameter can be used to specify device permissions by combining

for read,

for write, and

for mknod(2).

Example: --device=/dev/sdc:/dev/xvdc:rwm

Note: if host-device

is a symbolic link then it will be resolved first. The container will only store the major and minor numbers of the host device.

Podman may load kernel modules required for using the specified device. The devices that Podman will load modules for when necessary are: /dev/fuse.

In rootless mode, the new device is bind mounted in the container from the host rather than Podman creating it within the container space. Because the bind mount retains its SELinux label on SELinux systems, the container can get permission denied when accessing the mounted device. Modify SELinux settings to allow containers to use all device labels via the following command:

$ sudo setsebool -P container_use_devices=true

Note: if the user only has access rights via a group, accessing the device from inside a rootless container will fail. Use the

--group-add keep-groups

flag to pass the user's supplementary group access into the container.

--device-cgroup-rule

type major:minor mode

Add a rule to the cgroup allowed devices list. The rule is expected to be in the format specified in the Linux kernel documentation (Documentation/cgroup-v1/devices.txt):
- type: a (all), c (char), or b (block);
- major and minor: either a number, or * for all;
- mode: a composition of r (read), w (write), and m (mknod(2)).

--device-read-bps

path:rate

Limit read rate (in bytes per second) from a device (e.g. --device-read-bps=/dev/sda:1mb

This option is not supported on cgroups V1 rootless systems.

--device-read-iops

path:rate

Limit read rate (in IO operations per second) from a device (e.g. --device-read-iops=/dev/sda:1000

This option is not supported on cgroups V1 rootless systems.

--device-write-bps

path:rate

Limit write rate (in bytes per second) to a device (e.g. --device-write-bps=/dev/sda:1mb

This option is not supported on cgroups V1 rootless systems.

--device-write-iops

path:rate

Limit write rate (in IO operations per second) to a device (e.g. --device-write-iops=/dev/sda:1000

This option is not supported on cgroups V1 rootless systems.

--disable-content-trust

This is a Docker-specific option to disable image verification to a container registry and is not supported by Podman. This option is a NOOP and provided solely for scripting compatibility.

--dns

ipaddr

Set custom DNS servers.

This option can be used to override the DNS configuration passed to the container. Typically this is necessary when the host DNS configuration is invalid for the container (e.g., 127.0.0.1

). When this is the case the

--dns

flag is necessary for every run.

The special value none

can be specified to disable creation of

/etc/resolv.conf

in the container by Podman. The

/etc/resolv.conf

file in the image will be used without changes.

This option cannot be combined with --network

that is set to

none

container:

--dns-option

option

Set custom DNS options. Invalid if using --dns-option

with

--network

that is set to

none

container:

--dns-search

domain

Set custom DNS search domains. Invalid if using --dns-search

with

--network

that is set to

none

container:

. Use

--dns-search=.

to remove the search domain.

--entrypoint

command

'[ command , arg1 , ...]

Override the default ENTRYPOINT from the image.

The ENTRYPOINT of an image is similar to a COMMAND because it specifies what executable to run when the container starts, but it is (purposely) more difficult to override. The ENTRYPOINT gives a container its default nature or behavior. When the ENTRYPOINT is set, the container runs as if it were that binary, complete with default options. More options can be passed in via the COMMAND. But, if a user wants to run something else inside the container, the --entrypoint

option allows a new ENTRYPOINT to be specified.

Specify multi option commands in the form of a json string.

--env

-e

env

Set environment variables.

This option allows arbitrary environment variables that are available for the process to be launched inside of the container. If an environment variable is specified without a value, Podman will check the host environment for a value and set the variable only if it is set on the host. As a special case, if an environment variable ending in *

is specified without a value, Podman will search the host environment for variables starting with the prefix and will add those variables to the container.

See Environment

⟨#environment⟩ note below for precedence and examples.

--env-file

file

Read in a line-delimited file of environment variables.

See Environment

⟨#environment⟩ note below for precedence and examples.

--env-host

Use host environment inside of the container. See Environment

note below for precedence. (This option is not available with the remote Podman client, including Mac and Windows (excluding WSL2) machines)

--env-merge

env

Preprocess default environment variables for the containers. For example if image contains environment variable

hello=world

user can preprocess it using

--env-merge hello=${hello}-some

so new value will be

hello=world-some

--expose

port

Expose a port, or a range of ports (e.g. --expose=3300-3310

) to set up port redirection on the host system.

--gidmap

container_gid:host_gid:amount

Run the container in a new user namespace using the supplied GID mapping. This option conflicts with the --userns

and

--subgidname

options. This option provides a way to map host GIDs to container GIDs in the same way as

--uidmap

maps host UIDs to container UIDs. For details see

--uidmap

Note: the --gidmap

flag cannot be called in conjunction with the

--pod

flag as a gidmap cannot be set on the container level when in a pod.

--group-add

group

keep-groups

Assign additional groups to the primary user running within the container process.

•

keep-groups

is a special flag that tells Podman to keep the supplementary group access.

Allows container to use the user's supplementary group access. If file systems or devices are only accessible by the rootless user's group, this flag tells the OCI runtime to pass the group access into the container. Currently only available with the

crun

OCI runtime. Note:

keep-groups

is exclusive, other groups cannot be specified with this flag. (Not available for remote commands, including Mac and Windows (excluding WSL2) machines)

--health-cmd

command

'[ command , arg1 , ...]

Set or alter a healthcheck command for a container. The command is a command to be executed inside the container that determines the container health. The command is required for other healthcheck options to be applied. A value of none

disables existing healthchecks.

Multiple options can be passed in the form of a JSON array; otherwise, the command will be interpreted as an argument to /bin/sh -c

--health-interval

interval

Set an interval for the healthchecks. An interval

disable

results in no automatic timer setup. The default is

30s

--health-on-failure

action

Action to take once the container transitions to an unhealthy state. The default is none

•

none

: Take no action.

•

kill

: Kill the container.

•

restart

: Restart the container. Do not combine the

restart

action with the

--restart

flag. When running inside of a systemd unit, consider using the

kill

stop

action instead to make use of systemd's restart policy.

•

stop

: Stop the container.

--health-retries

retries

The number of retries allowed before a healthcheck is considered to be unhealthy. The default value is 3

--health-start-period

period

The initialization time needed for a container to bootstrap. The value can be expressed in time format like 2m3s

. The default value is

--health-startup-cmd

command

'[ command , arg1 , ...]

Set a startup healthcheck command for a container. This command will be executed inside the container and is used to gate the regular healthcheck. When the startup command succeeds, the regular healthcheck will begin and the startup healthcheck will cease. Optionally, if the command fails for a set number of attempts, the container will be restarted. A startup healthcheck can be used to ensure that containers with an extended startup period are not marked as unhealthy until they are fully started. Startup healthchecks can only be used when a regular healthcheck (from the container's image or the --health-cmd

option) is also set.

--health-startup-interval

interval

Set an interval for the startup healthcheck. An interval

disable

results in no automatic timer setup. The default is

30s

--health-startup-retries

retries

The number of attempts allowed before the startup healthcheck restarts the container. If set to 0

, the container will never be restarted. The default is

--health-startup-success

retries

The number of successful runs required before the startup healthcheck will succeed and the regular healthcheck will begin. A value of 0

means that any success will begin the regular healthcheck. The default is

--health-startup-timeout

timeout

The maximum time a startup healthcheck command has to complete before it is marked as failed. The value can be expressed in a time format like 2m3s

. The default value is

30s

--health-timeout

timeout

The maximum time allowed to complete the healthcheck before an interval is considered failed. Like start-period, the value can be expressed in a time format such as 1m22s

. The default value is

30s

--help

Print usage statement

--hostname

-h

name

Container host name

Sets the container host name that is available inside the container. Can only be used with a private UTS namespace

--uts=private

(default). If

--pod

is specified and the pod shares the UTS namespace (default) the pod's hostname will be used.

--hostuser

name

Add a user account to /etc/passwd from the host to the container. The Username or UID must exist on the host system.

--http-proxy

By default proxy environment variables are passed into the container if set for the Podman process. This can be disabled by setting the value to false

. The environment variables passed in include

http_proxy

https_proxy

ftp_proxy

no_proxy

, and also the upper case versions of those. This option is only needed when the host system must use a proxy but the container should not use any proxy. Proxy environment variables specified for the container in any other way will override the values that would have been passed through from the host. (Other ways to specify the proxy for the container include passing the values with the

--env

flag, or hard coding the proxy environment at container build time.) When used with the remote client it will use the proxy environment variables that are set on the server process.

Defaults to true

--image-volume

bind

tmpfs

ignore

Tells Podman how to handle the builtin image volumes. Default is bind

•

bind

: An anonymous named volume will be created and mounted into the container.

•

tmpfs

: The volume is mounted onto the container as a tmpfs, which allows the users to create content that disappears when the container is stopped.

•

ignore

: All volumes are just ignored and no action is taken.

--init

Run an init inside the container that forwards signals and reaps processes. The container-init binary is mounted at

/run/podman-init

. Mounting over

/run

will hence break container execution.

--init-path

path

Path to the container-init binary.

--interactive

-i

When set to true

, keep stdin open even if not attached. The default is

false

--ip

ipv4

Specify a static IPv4 address for the container, for example 10.88.64.128

. This option can only be used if the container is joined to only a single network - i.e.,

--network=network-name

is used at most once - and if the container is not joining another container's network namespace via

--network=container:

. The address must be within the network's IP address pool (default

10.88.0.0/16

To specify multiple static IP addresses per container, set multiple networks using the --network

option with a static IP address specified for each using the

ip

mode for that option.

--ip6

ipv6

Specify a static IPv6 address for the container, for example fd46:db93:aa76:ac37::10

. This option can only be used if the container is joined to only a single network - i.e.,

--network=network-name

is used at most once - and if the container is not joining another container's network namespace via

--network=container:

. The address must be within the network's IPv6 address pool.

To specify multiple static IPv6 addresses per container, set multiple networks using the --network

option with a static IPv6 address specified for each using the

ip6

mode for that option.

--ipc

ipc

Set the IPC namespace mode for a container. The default is to create a private IPC namespace.

•

": Use Podman's default, defined in containers.conf.

•

container:

: reuses another container's shared memory, semaphores, and message queues

•

host

: use the host's shared memory, semaphores, and message queues inside the container. Note: the host mode gives the container full access to local shared memory and is therefore considered insecure.

•

none

: private IPC namespace, with /dev/shm not mounted.

•

ns:

path

: path to an IPC namespace to join.

•

private

: private IPC namespace.

•

shareable

: private IPC namespace with a possibility to share it with other containers.

--label

-l

key=value

Add metadata to a container.

--label-file

file

Read in a line-delimited file of labels.

--link-local-ip

Not implemented.

--log-driver

driver

Logging driver for the container. Currently available options are k8s-file

journald

none

and

passthrough

, with

json-file

aliased to

k8s-file

for scripting compatibility. (Default

journald

The podman info command below will display the default log-driver for the system.

$ podman info --format '

{

{ .Host.LogDriver }

}

' journald

The passthrough

driver passes down the standard streams (stdin, stdout, stderr) to the container. It is not allowed with the remote Podman client, including Mac and Windows (excluding WSL2) machines, and on a tty, since it is vulnerable to attacks via TIOCSTI.

--log-opt

name=value

Logging driver specific options.

Set custom logging configuration. The following *name*s are supported:

path

: specify a path to the log file
(e.g.

--log-opt path=/var/log/container/mycontainer.json

);

max-size

: specify a max size of the log file
(e.g.

--log-opt max-size=10mb

);

tag

: specify a custom log tag for the container
(e.g.

--log-opt tag="

{

{.ImageName}

}

. It supports the same keys as

podman inspect --format

. This option is currently supported only by the

journald

log driver.

--mac-address

address

Container network interface MAC address (e.g. 92:d0:c6:0a:29:33) This option can only be used if the container is joined to only a single network - i.e., --network=

network-name

is used at most once - and if the container is not joining another container's network namespace via

--network=container:

Remember that the MAC address in an Ethernet network must be unique. The IPv6 link-local address will be based on the device's MAC address according to RFC4862.

To specify multiple static MAC addresses per container, set multiple networks using the --network

option with a static MAC address specified for each using the

mac

mode for that option.

--memory

-m

number[unit]

Memory limit. A unit

can be

(bytes),

(kibibytes),

(mebibytes), or

(gibibytes).

Allows the memory available to a container to be constrained. If the host supports swap memory, then the -m

memory setting can be larger than physical RAM. If a limit of 0 is specified (not using

-m

), the container's memory is not limited. The actual limit may be rounded up to a multiple of the operating system's page size (the value would be very large, that's millions of trillions).

This option is not supported on cgroups V1 rootless systems.

--memory-reservation

number[unit]

Memory soft limit. A unit

can be

(bytes),

(kibibytes),

(mebibytes), or

(gibibytes).

After setting memory reservation, when the system detects memory contention or low memory, containers are forced to restrict their consumption to their reservation. So always set the value below --memory

, otherwise the hard limit will take precedence. By default, memory reservation will be the same as memory limit.

This option is not supported on cgroups V1 rootless systems.

--memory-swap

number[unit]

A limit value equal to memory plus swap. A unit

can be

(bytes),

(kibibytes),

(mebibytes), or

(gibibytes).

Must be used with the -m

(

--memory

) flag. The argument value should always be larger than that of

-m

(

--memory

) By default, it is set to double the value of

--memory

Set number

-1

to enable unlimited swap.

This option is not supported on cgroups V1 rootless systems.

--memory-swappiness

number

Tune a container's memory swappiness behavior. Accepts an integer between 0

and

100

This flag is only supported on cgroups V1 rootful systems.

--mount

type=TYPE,TYPE-SPECIFIC-OPTION[,...]

Attach a filesystem mount to the container

Current supported mount TYPEs are bind

volume

image

tmpfs

and

devpts

. [1] ⟨#Footnote1⟩

e.g. type=bind,source=/path/on/host,destination=/path/in/container type=bind,src=/path/on/host,dst=/path/in/container,relabel=shared type=bind,src=/path/on/host,dst=/path/in/container,relabel=shared,U=true type=volume,source=vol1,destination=/path/in/container,ro=true type=tmpfs,tmpfs-size=512M,destination=/path/in/container type=image,source=fedora,destination=/fedora-image,rw=true type=devpts,destination=/dev/pts Common Options: · src, source: mount source spec for bind and volume. Mandatory for bind. · dst, destination, target: mount destination spec. Options specific to volume: · ro, readonly: true or false (default). . U, chown: true or false (default). Change recursively the owner and group of the source volume based on the UID and GID of the container. · idmap: true or false (default). If specified, create an idmapped mount to the target user namespace in the container. The idmap option supports a custom mapping that can be different than the user namespace used by the container. The mapping can be specified after the idmap option like: `idmap=uids=0-1-10#10-11-10;gids=0-100-10`. For each triplet, the first value is the start of the backing file system IDs that are mapped to the second value on the host. The length of this mapping is given in the third value. Multiple ranges are separated with #. Options specific to image: · rw, readwrite: true or false (default). Options specific to bind: · ro, readonly: true or false (default). · bind-propagation: shared, slave, private, unbindable, rshared, rslave, runbindable, or rprivate(default). See also mount(2). . bind-nonrecursive: do not set up a recursive bind mount. By default it is recursive. . relabel: shared, private. · idmap: true or false (default). If specified, create an idmapped mount to the target user namespace in the container. . U, chown: true or false (default). Change recursively the owner and group of the source volume based on the UID and GID of the container. Options specific to tmpfs: · ro, readonly: true or false (default). · tmpfs-size: Size of the tmpfs mount in bytes. Unlimited by default in Linux. · tmpfs-mode: File mode of the tmpfs in octal. (e.g. 700 or 0700.) Defaults to 1777 in Linux. · tmpcopyup: Enable copyup from the image directory at the same location to the tmpfs. Used by default. · notmpcopyup: Disable copying files from the image to the tmpfs. . U, chown: true or false (default). Change recursively the owner and group of the source volume based on the UID and GID of the container. Options specific to devpts: · uid: UID of the file owner (default 0). · gid: GID of the file owner (default 0). · mode: permission mask for the file (default 600). · max: maximum number of PTYs (default 1048576).

--name

name

Assign a name to the container.

The operator can identify a container in three ways:

• UUID long identifier (“f78375b1c487e03c9438c729345e54db9d20cfa2ac1fc3494b6eb60872e74778”);

• UUID short identifier (“f78375b1c487”);

• Name (“jonah”).

Podman generates a UUID for each container, and if a name is not assigned to the container with --name

then it will generate a random string name. The name can be useful as a more human-friendly way to identify containers. This works for both background and foreground containers.

--network

mode

--net

Set the network mode for the container.

Valid mode

values are:

•

bridge[:OPTIONS,...]

: Create a network stack on the default bridge. This is the default for rootful containers. It is possible to specify these additional options:

•

alias=name

: Add network-scoped alias for the container.

•

ip=IPv4

: Specify a static ipv4 address for this container.

•

ip=IPv6

: Specify a static ipv6 address for this container.

•

mac=MAC

: Specify a static mac address for this container.

•

interface_name

: Specify a name for the created network interface inside the container.

For example to set a static ipv4 address and a static mac address, use

--network bridge:ip=10.88.0.10,mac=44:33:22:11:00:99

•

<network name or ID>[:OPTIONS,...]: Connect to a user-defined network; this is the network name or ID from a network created by podman network create

. Using the network name implies the bridge network mode. It is possible to specify the same options described under the bridge mode above. Use the

--network

option multiple times to specify additional networks.

•

none

: Create a network namespace for the container but do not configure network interfaces for it, thus the container has no network connectivity.

•

container:

: Reuse another container's network stack.

•

host

: Do not create a network namespace, the container will use the host's network. Note: The host mode gives the container full access to local system services such as D-bus and is therefore considered insecure.

•

ns:

path

: Path to a network namespace to join.

•

private

: Create a new namespace for the container. This will use the

bridge

mode for rootful containers and

slirp4netns

for rootless ones.

•

slirp4netns[:OPTIONS,...]

: use slirp4netns(1) to create a user network stack. This is the default for rootless containers. It is possible to specify these additional options, they can also be set with

network_cmd_options

in containers.conf:

•

allow_host_loopback=true|false

: Allow slirp4netns to reach the host loopback IP (default is 10.0.2.2 or the second IP from slirp4netns cidr subnet when changed, see the cidr option below). The default is false.

•

mtu=MTU

: Specify the MTU to use for this network. (Default is

65520

•

cidr=CIDR

: Specify ip range to use for this network. (Default is

10.0.2.0/24

•

enable_ipv6=true|false

: Enable IPv6. Default is true. (Required for

outbound_addr6

•

outbound_addr=INTERFACE

: Specify the outbound interface slirp should bind to (ipv4 traffic only).

•

outbound_addr=IPv4

: Specify the outbound ipv4 address slirp should bind to.

•

outbound_addr6=INTERFACE

: Specify the outbound interface slirp should bind to (ipv6 traffic only).

•

outbound_addr6=IPv6

: Specify the outbound ipv6 address slirp should bind to.

•

port_handler=rootlesskit

: Use rootlesskit for port forwarding. Default. Note: Rootlesskit changes the source IP address of incoming packets to an IP address in the container network namespace, usually

10.0.2.100

. If the application requires the real source IP address, e.g. web server logs, use the slirp4netns port handler. The rootlesskit port handler is also used for rootless containers when connected to user-defined networks.

•

port_handler=slirp4netns

: Use the slirp4netns port forwarding, it is slower than rootlesskit but preserves the correct source IP address. This port handler cannot be used for user-defined networks.

•

pasta[:OPTIONS,...]

: use pasta(1) to create a user-mode networking stack.
This is only supported in rootless mode.
By default, IPv4 and IPv6 addresses and routes, as well as the pod interface name, are copied from the host. If port forwarding isn't configured, ports will be forwarded dynamically as services are bound on either side (init namespace or container namespace). Port forwarding preserves the original source IP address. Options described in pasta(1) can be specified as comma-separated arguments.
In terms of pasta(1) options,

--config-net

is given by default, in order to configure networking when the container is started, and

--no-map-gw

is also assumed by default, to avoid direct access from container to host using the gateway address. The latter can be overridden by passing

--map-gw

in the pasta-specific options (despite not being an actual pasta(1) option).
Also,

-t none

and

-u none

are passed if, respectively, no TCP or UDP port forwarding from host to container is configured, to disable automatic port forwarding based on bound ports. Similarly,

-T none

and

-U none

are given to disable the same functionality from container to host.
Some examples:

•

pasta:--map-gw

: Allow the container to directly reach the host using the gateway address.

•

pasta:--mtu,1500

: Specify a 1500 bytes MTU for the

tap

interface in the container.

•

pasta:--ipv4-only,-a,10.0.2.0,-n,24,-g,10.0.2.2,--dns-forward,10.0.2.3,-m,1500,--no-ndp,--no-dhcpv6,--no-dhcp

, equivalent to default slirp4netns(1) options: disable IPv6, assign

10.0.2.0/24

to the

tap0

interface in the container, with gateway

10.0.2.3

, enable DNS forwarder reachable at

10.0.2.3

, set MTU to 1500 bytes, disable NDP, DHCPv6 and DHCP support.

•

pasta:-I,tap0,--ipv4-only,-a,10.0.2.0,-n,24,-g,10.0.2.2,--dns-forward,10.0.2.3,--no-ndp,--no-dhcpv6,--no-dhcp

, equivalent to default slirp4netns(1) options with Podman overrides: same as above, but leave the MTU to 65520 bytes

•

pasta:-t,auto,-u,auto,-T,auto,-U,auto

: enable automatic port forwarding based on observed bound ports from both host and container sides

•

pasta:-T,5201

: enable forwarding of TCP port 5201 from container to host, using the loopback interface instead of the tap interface for improved performance

NOTE: For backward compatibility reasons, if there is an existing network named

pasta

, Podman will use it instead of the pasta mode."?

Invalid if using --dns

--dns-option

, or

--dns-search

with

--network

set to

none

container:

If used together with --pod

, the container will not join the pod's network namespace.

--network-alias

alias

Add a network-scoped alias for the container, setting the alias for all networks that the container joins. To set a name only for a specific network, use the alias option as described under the --network

option. If the network has DNS enabled (

podman network inspect -f {{.DNSEnabled}} <name>

), these aliases can be used for name resolution on the given network. This option can be specified multiple times. NOTE: When using CNI a container will only have access to aliases on the first network that it joins. This limitation does not exist with netavark/aardvark-dns.

--no-healthcheck

Disable any defined healthchecks for container.

--no-hosts

Do not create /etc/hosts

for the container. By default, Podman will manage

/etc/hosts

, adding the container's own IP address and any hosts from

--add-host

--no-hosts

disables this, and the image's

/etc/hosts

will be preserved unmodified.

This option conflicts with --add-host

--oom-kill-disable

Whether to disable OOM Killer for the container or not.

This flag is not supported on cgroups V2 systems.

--oom-score-adj

num

Tune the host's OOM preferences for containers (accepts values from -1000

1000

--os

Override the OS, defaults to hosts, of the image to be pulled. For example,

windows

. Unless overridden, subsequent lookups of the same image in the local storage will match this OS, regardless of the host.

--passwd

Allow Podman to add entries to /etc/passwd and /etc/group when used in conjunction with the --user option. This is used to override the Podman provided user setup in favor of entrypoint configurations such as libnss-extrausers.

--passwd-entry

ENTRY

Customize the entry that is written to the

/etc/passwd

file within the container when

--passwd

is used.

The variables $USERNAME, $UID, $GID, $NAME, $HOME are automatically replaced with their value at runtime.

--personality

persona

Personality sets the execution domain via Linux personality(2).

--pid

mode

Set the PID namespace mode for the container. The default is to create a private PID namespace for the container.

•

container:

: join another container's PID namespace;

•

host

: use the host's PID namespace for the container. Note the host mode gives the container full access to local PID and is therefore considered insecure;

•

ns:

path

: join the specified PID namespace;

•

private

: create a new namespace for the container (default).

--pidfile

path

When the pidfile location is specified, the container process' PID will be written to the pidfile. (This option is not available with the remote Podman client, including Mac and Windows (excluding WSL2) machines) If the pidfile option is not specified, the container process' PID will be written to /run/containers/storage/${storage-driver}-containers/$CID/userdata/pidfile.

After the container is started, the location for the pidfile can be discovered with the following

podman inspect

command:

$ podman inspect --format '

{

{ .PidFile }

}

' $CID /run/containers/storage/${storage-driver}-containers/$CID/userdata/pidfile

--pids-limit

limit

Tune the container's pids limit. Set to -1

to have unlimited pids for the container. The default is

2048

on systems that support "pids" cgroup controller.

--platform

OS/ARCH

Specify the platform for selecting the image. (Conflicts with --arch and --os) The

--platform

option can be used to override the current architecture and operating system. Unless overridden, subsequent lookups of the same image in the local storage will match this platform, regardless of the host.

--pod

name

Run container in an existing pod. Podman will make the pod automatically if the pod name is prefixed with new:

. To make a pod with more granular options, use the

podman pod create

command before creating a container. If a container is run with a pod, and the pod has an infra-container, the infra-container will be started before the container is.

--pod-id-file

file

Run container in an existing pod and read the pod's ID from the specified file

. If a container is run within a pod, and the pod has an infra-container, the infra-container will be started before the container is.

--preserve-fds

Pass down to the process N additional file descriptors (in addition to 0, 1, 2). The total FDs will be 3+N. (This option is not available with the remote Podman client, including Mac and Windows (excluding WSL2) machines)

--privileged

Give extended privileges to this container. The default is false

By default, Podman containers are unprivileged (

=false

) and cannot, for example, modify parts of the operating system. This is because by default a container is only allowed limited access to devices. A "privileged" container is given the same access to devices as the user launching the container, with the exception of virtual consoles (

/dev/tty+

) when running in systemd mode (

--systemd=always

A privileged container turns off the security features that isolate the container from the host. Dropped Capabilities, limited devices, read-only mount points, Apparmor/SELinux separation, and Seccomp filters are all disabled.

Rootless containers cannot have more privileges than the account that launched them.

--publish

-p

[

[ip:][hostPort]:]containerPort[/protocol]

Publish a container's port, or range of ports, to the host.

Both hostPort

and

containerPort

can be specified as a range of ports. When specifying ranges for both, the number of container ports in the range must match the number of host ports in the range.

If host IP is set to 0.0.0.0 or not set at all, the port will be bound on all IPs on the host.

By default, Podman will publish TCP ports. To publish a UDP port instead, give

udp

as protocol. To publish both TCP and UDP ports, set

--publish

twice, with

tcp

, and

udp

as protocols respectively. Rootful containers can also publish ports using the

sctp

protocol.

Host port does not have to be specified (e.g.

podman run -p 127.0.0.1::80

). If it is not, the container port will be randomly assigned a port on the host.

Use podman port

to see the actual mapping:

podman port $CONTAINER $CONTAINERPORT

Note:

If a container will be run within a pod, it is not necessary to publish the port for the containers in the pod. The port must only be published by the pod itself. Pod network stacks act like the network stack on the host - meaning a variety of containers in the pod and programs in the container all share a single interface, IP address, and associated ports. If one container binds to a port, no other container can use that port within the pod while it is in use. Containers in the pod can also communicate over localhost by having one container bind to localhost in the pod, and another connect to that port.

--publish-all

-P

Publish all exposed ports to random ports on the host interfaces. The default is false

When set to true

, publish all exposed ports to the host interfaces. If the operator uses

-P

(or

-p

) then Podman will make the exposed port accessible on the host and the ports will be available to any client that can reach the host.

When using this option, Podman will bind any exposed port to a random port on the host within an ephemeral port range defined by /proc/sys/net/ipv4/ip_local_port_range

. To find the mapping between the host ports and the exposed ports, use

podman port

--pull

policy

Pull image policy. The default is missing

•

always

: Always pull the image and throw an error if the pull fails.

•

missing

: Pull the image only if it could not be found in the local containers storage. Throw an error if no image could be found and the pull fails.

•

never

: Never pull the image but use the one from the local containers storage. Throw an error if no image could be found.

•

newer

: Pull if the image on the registry is newer than the one in the local containers storage. An image is considered to be newer when the digests are different. Comparing the time stamps is prone to errors. Pull errors are suppressed if a local image was found.

--quiet

-q

Suppress output information when pulling images

--read-only

Mount the container's root filesystem as read-only.

By default a container will have its root filesystem writable allowing processes to write files anywhere. By specifying the --read-only

flag, the container will have its root filesystem mounted as read-only prohibiting any writes.

--read-only-tmpfs

If container is running in --read-only

mode, then mount a read-write tmpfs on

/run

/tmp

, and

/var/tmp

. The default is

true

--replace

If another container with the same name already exists, replace and remove it. The default is false

--requires

container

Specify one or more requirements. A requirement is a dependency container that will be started before this container. Containers can be specified by name or ID, with multiple containers being separated by commas.

--restart

policy

Restart policy to follow when containers exit. Restart policy will not take effect if a container is stopped via the podman kill

podman stop

commands.

Valid policy

values are:

•

no

: Do not restart containers on exit

•

on-failure[:max_retries]

: Restart containers when they exit with a non-zero exit code, retrying indefinitely or until the optional

max_retries

count is hit

•

always

: Restart containers when they exit, regardless of status, retrying indefinitely

•

unless-stopped

: Identical to

always

Podman provides a systemd unit file, podman-restart.service, which restarts containers after a system reboot.

If container will run as a system service, generate a systemd unit file to manage it. See podman generate systemd

--rm

Automatically remove the container when it exits. The default is false

--rmi

After exit of the container, remove the image unless another container is using it. The default is false

--rootfs

If specified, the first argument refers to an exploded container on the file system.

This is useful to run a container without requiring any image management, the rootfs of the container is assumed to be managed externally.

Overlay Rootfs Mounts

The

:O

flag tells Podman to mount the directory from the rootfs path as storage using the

overlay file system

. The container processes can modify content within the mount point which is stored in the container storage in a separate directory. In overlay terms, the source directory will be the lower, and the container storage directory will be the upper. Modifications to the mount point are destroyed when the container finishes executing, similar to a tmpfs mount point being unmounted.

Note: On SELinux

systems, the rootfs needs the correct label, which is by default

unconfined_u:object_r:container_file_t:s0

--sdnotify

container

conmon

ignore

Determines how to use the NOTIFY_SOCKET, as passed with systemd and Type=notify.

Default is container

, which means allow the OCI runtime to proxy the socket into the container to receive ready notification. Podman will set the MAINPID to conmon's pid. The

conmon

option sets MAINPID to conmon's pid, and sends READY when the container has started. The socket is never passed to the runtime or the container. The

ignore

option removes NOTIFY_SOCKET from the environment for itself and child processes, for the case where some other process above Podman uses NOTIFY_SOCKET and Podman should not use it.

--seccomp-policy

policy

Specify the policy to select the seccomp profile. If set to image

, Podman will look for a "io.containers.seccomp.profile" label in the container-image config and use its value as a seccomp profile. Otherwise, Podman will follow the

default

policy by applying the default profile unless specified otherwise via

--security-opt seccomp

as described below.

Note that this feature is experimental and may change in the future.

--secret

secret[,opt=opt ...]

Give the container access to a secret. Can be specified multiple times.

A secret is a blob of sensitive data which a container needs at runtime but should not be stored in the image or in source control, such as usernames and passwords, TLS certificates and keys, SSH keys or other important generic strings or binary content (up to 500 kb in size).

When secrets are specified as type

mount

, the secrets are copied and mounted into the container when a container is created. When secrets are specified as type

env

, the secret will be set as an environment variable within the container. Secrets are written in the container at the time of container creation, and modifying the secret using

podman secret

commands after the container is created will not affect the secret inside the container.

Secrets and its storage are managed using the

podman secret

command.

Secret Options

•

type=mount|env

: How the secret will be exposed to the container.

mount

mounts the secret into the container as a file.

env

exposes the secret as a environment variable.
Defaults to

mount

•

target=target

: Target of secret.
For mounted secrets, this is the path to the secret inside the container.
If a fully qualified path is provided, the secret will be mounted at that location.
Otherwise, the secret will be mounted to

/run/secrets/target

.
If target is not set, by default the secret will be mounted to

/run/secrets/secretname

.
For env secrets, this is the environment variable key. Defaults to

secretname

•

uid=0

: UID of secret. Defaults to 0. Mount secret type only.

•

gid=0

: GID of secret. Defaults to 0. Mount secret type only.

•

mode=0

: Mode of secret. Defaults to 0444. Mount secret type only.

Examples

Mount at

/my/location/mysecret

with UID 1:

--secret mysecret,target=/my/location/mysecret,uid=1

Mount at

/run/secrets/customtarget

with mode 0777:

--secret mysecret,target=customtarget,mode=0777

Create a secret environment variable called

ENVSEC

--secret mysecret,type=env,target=ENVSEC

--security-opt

option

Security Options

•

apparmor=unconfined

: Turn off apparmor confinement for the container

•

apparmor

alternate-profile

: Set the apparmor confinement profile for the container

•

label=user:

USER

: Set the label user for the container processes

•

label=role:

ROLE

: Set the label role for the container processes

•

label=type:

TYPE

: Set the label process type for the container processes

•

label=level:

LEVEL

: Set the label level for the container processes

•

label=filetype:

TYPE

: Set the label file type for the container files

•

label=disable

: Turn off label separation for the container

Note: Labeling can be disabled for all containers by setting label=false in the containers.conf

(

/etc/containers/containers.conf

$HOME/.config/containers/containers.conf

) file.

•

mask

/path/1:/path/2

: The paths to mask separated by a colon. A masked path cannot be accessed inside the container.

•

no-new-privileges

: Disable container processes from gaining additional privileges.

•

seccomp=unconfined

: Turn off seccomp confinement for the container.

•

seccomp=profile.json

: JSON file to be used as a seccomp filter. Note that the

io.podman.annotations.seccomp

annotation is set with the specified value as shown in

podman inspect

•

proc-opts

OPTIONS

: Comma-separated list of options to use for the /proc mount. More details for the possible mount options are specified in the

proc(5)

man page.

•

unmask

ALL

/path/1:/path/2

, or shell expanded paths (/proc/*): Paths to unmask separated by a colon. If set to

ALL

, it will unmask all the paths that are masked or made read-only by default. The default masked paths are

/proc/acpi, /proc/kcore, /proc/keys, /proc/latency_stats, /proc/sched_debug, /proc/scsi, /proc/timer_list, /proc/timer_stats, /sys/firmware, and /sys/fs/selinux

. The default paths that are read-only are

/proc/asound

/proc/bus

/proc/fs

/proc/irq

/proc/sys

/proc/sysrq-trigger

/sys/fs/cgroup

Note: Labeling can be disabled for all containers by setting label=false

in the containers.conf(5) file.

--shm-size

number[unit]

Size of /dev/shm

. A

unit

can be

(bytes),

(kibibytes),

(mebibytes), or

(gibibytes). If the unit is omitted, the system uses bytes. If the size is omitted, the default is

64m

. When

size

, there is no limit on the amount of memory used for IPC by the container. This option conflicts with

--ipc=host

--sig-proxy

Proxy received signals to the container process (non-TTY mode only). SIGCHLD, SIGSTOP, and SIGKILL are not proxied.

The default is true

--stop-signal

signal

Signal to stop a container. Default is SIGTERM

--stop-timeout

seconds

Timeout to stop a container. Default is 10

. Remote connections use local containers.conf for defaults

--subgidname

name

Run the container in a new user namespace using the map with name

in the

/etc/subgid

file. If running rootless, the user needs to have the right to use the mapping. See subgid(5). This flag conflicts with

--userns

and

--gidmap

--subuidname

name

Run the container in a new user namespace using the map with name

in the

/etc/subuid

file. If running rootless, the user needs to have the right to use the mapping. See subuid(5). This flag conflicts with

--userns

and

--uidmap

--sysctl

name=value

Configure namespaced kernel parameters at runtime.

For the IPC namespace, the following sysctls are allowed:

• kernel.msgmax

• kernel.msgmnb

• kernel.msgmni

• kernel.sem

• kernel.shmall

• kernel.shmmax

• kernel.shmmni

• kernel.shm_rmid_forced

• Sysctls beginning with fs.mqueue.*

Note: if using the --ipc=host

option, the above sysctls are not allowed.

For the network namespace, only sysctls beginning with net.* are allowed.

Note: if using the --network=host

option, the above sysctls are not allowed.

--systemd

true

false

always

Run container in systemd mode. The default is true

•

true

enables systemd mode only when the command executed inside the container is

systemd

/usr/sbin/init

/sbin/init

/usr/local/sbin/init

, systemd mode is enabled.

•

false

disables systemd mode.

•

always

enforces the systemd mode to be enabled.

Running the container in systemd mode causes the following changes:

• Podman mounts tmpfs file systems on the following directories

•

/run

•

/run/lock

•

/tmp

•

/sys/fs/cgroup/systemd

•

/var/lib/journal

• Podman sets the default stop signal to SIGRTMIN+3

• Podman sets container_uuid

environment variable in the container to the first 32 characters of the container id.

• Podman will not mount virtual consoles (

/dev/tty+

) when running with

--privileged

This allows systemd to run in a confined container without any modifications.

Note that on SELinux

systems, systemd attempts to write to the cgroup file system. Containers writing to the cgroup file system are denied by default. The

container_manage_cgroup

boolean must be enabled for this to be allowed on an SELinux separated system.

setsebool -P container_manage_cgroup true

--timeout

seconds

Maximum time a container is allowed to run before conmon sends it the kill signal. By default containers will run until they exit or are stopped by

podman stop

--tls-verify

Require HTTPS and verify certificates when contacting registries (default: true

). If explicitly set to

true

, TLS verification will be used. If set to

false

, TLS verification will not be used. If not specified, TLS verification will be used unless the target registry is listed as an insecure registry in

containers-registries.conf(5)

--tmpfs

Create a tmpfs mount.

Mount a temporary filesystem (

tmpfs

) mount into a container, for example:

$ podman run -d --tmpfs /tmp:rw,size=787448k,mode=1777 my_image

This command mounts a tmpfs

/tmp

within the container. The supported mount options are the same as the Linux default mount flags. If no options are specified, the system uses the following options:

rw,noexec,nosuid,nodev

--tty

-t

Allocate a pseudo-TTY. The default is false

When set to true

, Podman will allocate a pseudo-tty and attach to the standard input of the container. This can be used, for example, to run a throwaway interactive shell.

NOTE

: The --tty flag prevents redirection of standard output. It combines STDOUT and STDERR, it can insert control characters, and it can hang pipes. This option should only be used when run interactively in a terminal. When feeding input to Podman, use -i only, not -it.

echo "asdf" | podman run --rm -i someimage /bin/cat

--tz

timezone

Set timezone in container. This flag takes area-based timezones, GMT time, as well as

local

, which sets the timezone in the container to match the host machine. See

/usr/share/zoneinfo/

for valid timezones. Remote connections use local containers.conf for defaults

--uidmap

container_uid:from_uid:amount

Run the container in a new user namespace using the supplied UID mapping. This option conflicts with the --userns

and

--subuidname

options. This option provides a way to map host UIDs to container UIDs. It can be passed several times to map different ranges.

The _fromuid

value is based upon the user running the command, either rootful or rootless users. * rootful user:

container_uid

host_uid

amount

* rootless user:

container_uid

intermediate_uid

amount

When podman run

is called by a privileged user, the option

--uidmap

works as a direct mapping between host UIDs and container UIDs.

host UID -> container UID

The amount

specifies the number of consecutive UIDs that will be mapped. If for example

amount

the mapping would look like:

| _container

uid

| | _from

uid

+ 1 | _container

uid

+ 1 | | _from

uid

+ 2 | _container

uid

+ 2 | | _from

uid

+ 3 | _container

uid

+ 3 |

When podman run

is called by an unprivileged user (i.e. running rootless), the value _from

uid

is interpreted as an "intermediate UID". In the rootless case, host UIDs are not mapped directly to container UIDs. Instead the mapping happens over two mapping steps:

host UID -> intermediate UID -> container UID

The --uidmap

option only influences the second mapping step.

The first mapping step is derived by Podman from the contents of the file /etc/subuid

and the UID of the user calling Podman.

First mapping step:

| host UID | intermediate UID | | - | - | | UID for the user starting Podman | 0 | | 1st subordinate UID for the user starting Podman | 1 | | 2nd subordinate UID for the user starting Podman | 2 | | 3rd subordinate UID for the user starting Podman | 3 | | nth subordinate UID for the user starting Podman | n |

To be able to use intermediate UIDs greater than zero, the user needs to have subordinate UIDs configured in /etc/subuid

. See subuid(5).

The second mapping step is configured with --uidmap

If for example amount

the second mapping step would look like:

| _container

uid

| | _from

uid

+ 1 | _container

uid

+ 1 | | _from

uid

+ 2 | _container

uid

+ 2 | | _from

uid

+ 3 | _container

uid

+ 3 | | _from

uid

+ 4 | _container

uid

+ 4 |

When running as rootless, Podman will use all the ranges configured in the /etc/subuid

file.

The current user ID is mapped to UID=0 in the rootless user namespace. Every additional range is added sequentially afterward:

| host |rootless user namespace | length | | - | - | - | | $UID | 0 | 1 | | 1 | $FIRST_RANGE_ID | $FIRST_RANGE_LENGTH | | 1+$FIRST_RANGE_LENGTH | $SECOND_RANGE_ID | $SECOND_RANGE_LENGTH|

Even if a user does not have any subordinate UIDs in /etc/subuid

--uidmap

could still be used to map the normal UID of the user to a container UID by running

podman run --uidmap $container_uid:0:1 --user $container_uid ...

Note: the --uidmap

flag cannot be called in conjunction with the

--pod

flag as a uidmap cannot be set on the container level when in a pod.

--ulimit

option

Ulimit options. You can use host

to copy the current configuration from the host.

--umask

umask

Set the umask inside the container. Defaults to

0022

. Remote connections use local containers.conf for defaults

--unsetenv

env

Unset default environment variables for the container. Default environment variables include variables provided natively by Podman, environment variables configured by the image, and environment variables from containers.conf.

--unsetenv-all

Unset all default environment variables for the container. Default environment variables include variables provided natively by Podman, environment variables configured by the image, and environment variables from containers.conf.

--user

-u

user[:group]

Sets the username or UID used and, optionally, the groupname or GID for the specified command. Both user

and

group

may be symbolic or numeric.

Without this argument, the command will run as the user specified in the container image. Unless overridden by a

USER

command in the Containerfile or by a value passed to this option, this user generally defaults to root.

When a user namespace is not in use, the UID and GID used within the container and on the host will match. When user namespaces are in use, however, the UID and GID in the container may correspond to another UID and GID on the host. In rootless containers, for example, a user namespace is always used, and root in the container will by default correspond to the UID and GID of the user invoking Podman.

--userns

mode

Set the user namespace mode for the container. It defaults to the PODMAN_USERNS

environment variable. An empty value (

) means user namespaces are disabled unless an explicit mapping is set with the

--uidmap

and

--gidmap

options.

This option is incompatible with --gidmap

--uidmap

--subuidname

and

--subgidname

Rootless user --userns=Key mappings:

Key	Host User	Container User
""	$UID	0 (Default User account mapped to root user in container.)
keep-id	$UID	$UID (Map user account to same UID within container.)
keep-id:uid=200,gid=210	$UID	200:210 (Map user account to specified uid, gid value within container.)
auto	$UID	nil (Host User UID is not mapped into container.)
nomap	$UID	nil (Host User UID is not mapped into container.)

Valid mode

values are:

auto

OPTIONS,...

]: automatically create a unique user namespace.

The

--userns=auto

flag requires that the user name

containers

be specified in the /etc/subuid and /etc/subgid files, with an unused range of subordinate user IDs that Podman containers are allowed to allocate. See subuid(5).

Example:

containers:2147483647:2147483648

Podman allocates unique ranges of UIDs and GIDs from the

containers

subordinate user ids. The size of the ranges is based on the number of UIDs required in the image. The number of UIDs and GIDs can be overridden with the

size

option.

The rootless option

--userns=keep-id

uses all the subuids and subgids of the user. Using

--userns=auto

when starting new containers will not work as long as any containers exist that were started with

--userns=keep-id

Valid

auto

options:

•

gidmapping

CONTAINER_GID:HOST_GID:SIZE

: to force a GID mapping to be present in the user namespace.

•

size

SIZE

: to specify an explicit size for the automatic user namespace. e.g.

--userns=auto:size=8192

. If

size

is not specified,

auto

will estimate a size for the user namespace.

•

uidmapping

CONTAINER_UID:HOST_UID:SIZE

: to force a UID mapping to be present in the user namespace.

container:

: join the user namespace of the specified container.

host

: run in the user namespace of the caller. The processes running in the container will have the same privileges on the host as any other process launched by the calling user (default).

keep-id

: creates a user namespace where the current rootless user's UID:GID are mapped to the same values in the container. This option is not allowed for containers created by the root user.

Valid

keep-id

options:

•

uid

=UID: override the UID inside the container that will be used to map the current rootless user to.

•

gid

=GID: override the GID inside the container that will be used to map the current rootless user to.

nomap

: creates a user namespace where the current rootless user's UID:GID are not mapped into the container. This option is not allowed for containers created by the root user.

ns:

namespace

: run the container in the given existing user namespace.

--uts

mode

Set the UTS namespace mode for the container. The following values are supported:

•

host

: use the host's UTS namespace inside the container.

•

private

: create a new namespace for the container (default).

•

ns:[path]

: run the container in the given existing UTS namespace.

•

container:[container]

: join the UTS namespace of the specified container.

--variant

VARIANT

Use VARIANT

instead of the default architecture variant of the container image. Some images can use multiple variants of the arm architectures, such as arm/v5 and arm/v7.

--volume

-v

[

[SOURCE-VOLUME|HOST-DIR:]CONTAINER-DIR[:OPTIONS]

]

Create a bind mount. If

-v /HOST-DIR:/CONTAINER-DIR

is specified, Podman bind mounts

/HOST-DIR

from the host into

/CONTAINER-DIR

in the Podman container. Similarly,

-v SOURCE-VOLUME:/CONTAINER-DIR

will mount the named volume from the host into the container. If no such named volume exists, Podman will create one. If no source is given, the volume will be created as an anonymously named volume with a randomly generated name, and will be removed when the container is removed via the

--rm

flag or the

podman rm --volumes

command.

(Note when using the remote client, including Mac and Windows (excluding WSL2) machines, the volumes will be mounted from the remote server, not necessarily the client machine.)

The OPTIONS

is a comma-separated list and can be: [1] ⟨#Footnote1⟩

•

[

]

•

[

]

•

[

]

copy

•

[

]

dev

•

[

]

exec

•

[

]

suid

•

[

]

bind

•

[

]

shared

]

slave

]

private

[

]

unbindable

•

idmap

options

]

The

CONTAINER-DIR

must be an absolute path such as

/src/docs

. The volume will be mounted into the container at this directory.

If a volume source is specified, it must be a path on the host or the name of a named volume. Host paths are allowed to be absolute or relative; relative paths are resolved relative to the directory Podman is run in. If the source does not exist, Podman will return an error. Users must pre-create the source files or directories.

Any source that does not begin with a

​.

/

will be treated as the name of a named volume. If a volume with that name does not exist, it will be created. Volumes created with names are not anonymous, and they are not removed by the

--rm

option and the

podman rm --volumes

command.

Specify multiple -v

options to mount one or more volumes into a container.

Write Protected Volume Mounts

Add :ro

:rw

option to mount a volume in read-only or read-write mode, respectively. By default, the volumes are mounted read-write. See examples.

Chowning Volume Mounts

By default, Podman does not change the owner and group of source volume directories mounted into containers. If a container is created in a new user namespace, the UID and GID in the container may correspond to another UID and GID on the host.

The

:U

suffix tells Podman to use the correct host UID and GID based on the UID and GID within the container, to change recursively the owner and group of the source volume. Chowning walks the file system under the volume and changes the UID/GID on each file, it the volume has thousands of inodes, this process will take a long time, delaying the start of the container.

Warning

use with caution since this will modify the host filesystem.

Labeling Volume Mounts

Labeling systems like SELinux require that proper labels are placed on volume content mounted into a container. Without a label, the security system might prevent the processes running inside the container from using the content. By default, Podman does not change the labels set by the OS.

To change a label in the container context, add either of two suffixes :z

to the volume mount. These suffixes tell Podman to relabel file objects on the shared volumes. The

option tells Podman that two or more containers share the volume content. As a result, Podman labels the content with a shared content label. Shared volume labels allow all containers to read/write content. The

option tells Podman to label the content with a private unshared label Only the current container can use a private volume. Relabeling walks the file system under the volume and changes the label on each file, it the volume has thousands of inodes, this process will take a long time, delaying the start of the container. If the volume was previously relabeled with the

z

option, Podman is optimized to not relabel a second time. If files are moved into the volume, then the labels can be manually change with the

chcon -R container_file_t PATH

command.

Note: Do not relabel system files and directories. Relabeling system content might cause other confined services on the machine to fail. For these types of containers we recommend disabling SELinux separation. The option --security-opt label=disable

disables SELinux separation for the container. For example if a user wanted to volume mount their entire home directory into a container, they need to disable SELinux separation.

$ podman run --security-opt label=disable -v $HOME:/home/user fedora touch /home/user/file

Overlay Volume Mounts

The

:O

flag tells Podman to mount the directory from the host as a temporary storage using the

overlay file system

. The container processes can modify content within the mountpoint which is stored in the container storage in a separate directory. In overlay terms, the source directory will be the lower, and the container storage directory will be the upper. Modifications to the mount point are destroyed when the container finishes executing, similar to a tmpfs mount point being unmounted.

For advanced users, the overlay

option also supports custom non-volatile

upperdir

and

workdir

for the overlay mount. Custom

upperdir

and

workdir

can be fully managed by the users themselves, and Podman will not remove it on lifecycle completion. Example

:O,upperdir=/some/upper,workdir=/some/work

Subsequent executions of the container will see the original source directory content, any changes from previous container executions no longer exist.

One use case of the overlay mount is sharing the package cache from the host into the container to allow speeding up builds.

Note:

- The `O` flag conflicts with other options listed above.

Content mounted into the container is labeled with the private label.
On SELinux systems, labels in the source directory must be readable by the container label. Usually containers can read/execute

container_share_t

and can read/write

container_file_t

. If unable to change the labels on a source volume, SELinux container separation must be disabled for the container to work.
- The source directory mounted into the container with an overlay mount should not be modified, it can cause unexpected failures. It is recommended to not modify the directory until the container finishes running.

Mounts propagation

By default bind mounted volumes are

private

. That means any mounts done inside the container will not be visible on host and vice versa. One can change this behavior by specifying a volume mount propagation property. Making a volume shared mounts done under that volume inside the container will be visible on host and vice versa. Making a volume

slave

enables only one way mount propagation and that is mounts done on host under that volume will be visible inside container but not the other way around. [1] ⟨#Footnote1⟩

To control mount propagation property of a volume one can use the [

]

shared

, [

]

slave

, [

]

private

or the [

]

unbindable

propagation flag. Propagation property can be specified only for bind mounted volumes and not for internal volumes or named volumes. For mount propagation to work the source mount point (the mount point where source dir is mounted on) has to have the right propagation properties. For shared volumes, the source mount point has to be shared. And for slave volumes, the source mount point has to be either shared or slave. [1] ⟨#Footnote1⟩

To recursively mount a volume and all of its submounts into a container, use the rbind

option. By default the bind option is used, and submounts of the source directory will not be mounted into the container.

Mounting the volume with a copy

option tells podman to copy content from the underlying destination directory onto newly created internal volumes. The

copy

only happens on the initial creation of the volume. Content is not copied up when the volume is subsequently used on different containers. The

copy

option is ignored on bind mounts and has no effect.

Mounting the volume with the nosuid

options means that SUID applications on the volume will not be able to change their privilege. By default volumes are mounted with

nosuid

Mounting the volume with the noexec

option means that no executables on the volume will be able to be executed within the container.

Mounting the volume with the nodev

option means that no devices on the volume will be able to be used by processes within the container. By default volumes are mounted with

nodev

If the HOST-DIR

is a mount point, then

dev

suid

, and

exec

options are ignored by the kernel.

Use df HOST-DIR

to figure out the source mount, then use

findmnt -o TARGET,PROPAGATION

source-mount-dir

to figure out propagation properties of source mount. If findmnt(1) utility is not available, then one can look at the mount entry for the source mount point in

/proc/self/mountinfo

. Look at the "optional fields" and see if any propagation properties are specified. In there,

shared:N

means the mount is shared,

master:N

means mount is slave, and if nothing is there, the mount is private. [1] ⟨#Footnote1⟩

To change propagation properties of a mount point, use mount(8) command. For example, if one wants to bind mount source directory /foo

, one can do

mount --bind /foo /foo

and

mount --make-private --make-shared /foo

. This will convert /foo into a shared mount point. Alternatively, one can directly change propagation properties of source mount. Say

is source mount for

/foo

, then use

mount --make-shared /

to convert

into a shared mount.

Note: if the user only has access rights via a group, accessing the volume from inside a rootless container will fail.

Idmapped mount

idmap

is specified, create an idmapped mount to the target user namespace in the container. The idmap option supports a custom mapping that can be different than the user namespace used by the container. The mapping can be specified after the idmap option like:

idmap=uids=0-1-10#10-11-10;gids=0-100-10

. For each triplet, the first value is the start of the backing file system IDs that are mapped to the second value on the host. The length of this mapping is given in the third value. Multiple ranges are separated with #.

Use the --group-add keep-groups

option to pass the user's supplementary group access into the container.

--volumes-from

CONTAINER[:OPTIONS]

Mount volumes from the specified container(s). Used to share volumes between containers. The options

is a comma-separated list with the following available elements:

•

Mounts already mounted volumes from a source container onto another container. CONTAINER

may be a name or ID. To share a volume, use the --volumes-from option when running the target container. Volumes can be shared even if the source container is not running.

By default, Podman mounts the volumes in the same mode (read-write or read-only) as it is mounted in the source container. This can be changed by adding a

ro

rw

option

To change a label in the container context, add

z

to the volume mount. This suffix tells Podman to relabel file objects on the shared volumes. The

z

option tells Podman that two entities share the volume content. As a result, Podman labels the content with a shared content label. Shared volume labels allow all containers to read/write content.

If the location of the volume from the source container overlaps with data residing on a target container, then the volume hides that data on the target.

--workdir

-w

dir

Working directory inside the container.

The default working directory for running binaries within a container is the root directory (

). The image developer can set a different default with the WORKDIR instruction. The operator can override the working directory by using the

-w

option.

Exit Status

The exit code from podman run

gives information about why the container failed to run or why it exited. When

podman run

exits with a non-zero code, the exit codes follow the chroot(1) standard, see below:

125

The error is with Podman itself

$ podman run --foo busybox; echo $? Error: unknown flag: --foo 125

126

The

contained command

cannot be invoked

$ podman run busybox /etc; echo $? Error: container_linux.go:346: starting container process caused "exec: \"/etc\\": permission denied": OCI runtime error 126

127

The

contained command

cannot be found

$ podman run busybox foo; echo $? Error: container_linux.go:346: starting container process caused "exec: \"foo\\": executable file not found in $PATH": OCI runtime error 127

Exit code

contained command

exit code

$ podman run busybox /bin/sh -c 'exit 3'; echo $? 3

EXAMPLES

Running container in read-only mode

During container image development, containers often need to write to the image content. Installing packages into /usr

, for example. In production, applications seldom need to write to the image. Container applications write to volumes if they need to write to file systems at all. Applications can be made more secure by running them in read-only mode using the

--read-only

switch. This protects the container's image from modification. By default read-only containers can write to temporary data. Podman mounts a tmpfs on

/run

and

/tmp

within the container. If the container should not write to any file system within the container, including tmpfs, set --read-only-tmpfs=false.

$ podman run --read-only -i -t fedora /bin/bash $ podman run --read-only --read-only-tmpfs=false --tmpfs /run -i -t fedora /bin/bash

Exposing log messages from the container to the host's log

Bind mount the /dev/log

directory to have messages that are logged in the container show up in the host's syslog/journal.

$ podman run -v /dev/log:/dev/log -i -t fedora /bin/bash

From inside the container test this by sending a message to the log.

(bash)# logger "Hello from my container"

Then exit and check the journal.

(bash)# exit $ journalctl -b | grep Hello

This should list the message sent to logger.

Attaching to one or more from STDIN, STDOUT, STDERR

Without specifying the -a

option, Podman will attach everything (stdin, stdout, stderr). Override the default by specifying -a (stdin, stdout, stderr), as in:

$ podman run -a stdin -a stdout -i -t fedora /bin/bash

Using shm_server.c

available here: https://www.cs.cf.ac.uk/Dave/C/node27.html

Testing --ipc=host

mode:

Host shows a shared memory segment with 7 pids attached, happens to be from httpd:

$ sudo ipcs -m ------ Shared Memory Segments -------- key shmid owner perms bytes nattch status 0x01128e25 0 root 600 1000 7

Now run a regular container, and it correctly does NOT see the shared memory segment from the host:

$ podman run -it shm ipcs -m ------ Shared Memory Segments -------- key shmid owner perms bytes nattch status

Run a container with the new --ipc=host

option, and it now sees the shared memory segment from the host httpd:

$ podman run -it --ipc=host shm ipcs -m ------ Shared Memory Segments -------- key shmid owner perms bytes nattch status 0x01128e25 0 root 600 1000 7

Testing --ipc=container:

mode:

Start a container with a program to create a shared memory segment:

$ podman run -it shm bash $ sudo shm/shm_server & $ sudo ipcs -m ------ Shared Memory Segments -------- key shmid owner perms bytes nattch status 0x0000162e 0 root 666 27 1

Create a 2nd container correctly shows no shared memory segment from 1st container:

$ podman run shm ipcs -m ------ Shared Memory Segments -------- key shmid owner perms bytes nattch status

Create a 3rd container using the --ipc=container:

option, now it shows the shared memory segment from the first:

$ podman run -it --ipc=container:ed735b2264ac shm ipcs -m $ sudo ipcs -m ------ Shared Memory Segments -------- key shmid owner perms bytes nattch status 0x0000162e 0 root 666 27 1

Mapping Ports for External Usage

The exposed port of an application can be mapped to a host port using the -p

flag. For example, an httpd port 80 can be mapped to the host port 8080 using the following:

$ podman run -p 8080:80 -d -i -t fedora/httpd

Mounting External Volumes

To mount a host directory as a container volume, specify the absolute path to the directory and the absolute path for the container directory separated by a colon. If the source is a named volume maintained by Podman, it is recommended to use its name rather than the path to the volume. Otherwise the volume will be considered as an orphan and wiped by the podman volume prune

command:

$ podman run -v /var/db:/data1 -i -t fedora bash $ podman run -v data:/data2 -i -t fedora bash $ podman run -v /var/cache/dnf:/var/cache/dnf:O -ti fedora dnf -y update

If the container needs a writeable mounted volume by a non root user inside the container, use the U

option. This option tells Podman to chown the source volume to match the default UID and GID used within the container.

$ podman run -d -e MYSQL_ROOT_PASSWORD=root --user mysql --userns=keep-id -v ~/data:/var/lib/mysql:z,U mariadb

Alternatively if the container needs a writable volume by a non root user inside of the container, the --userns=keep-id option allows users to specify the UID and GID of the user executing Podman to specific UIDs and GIDs within the container. Since the processes running in the container run as the user's UID, they can read/write files owned by the user.

$ podman run -d -e MYSQL_ROOT_PASSWORD=root --user mysql --userns=keep-id:uid=999,gid=999 -v ~/data:/var/lib/mysql:z mariadb

Using --mount

flags to mount a host directory as a container folder, specify the absolute path to the directory or the volume name, and the absolute path within the container directory:

$ podman run --mount type=bind,src=/var/db,target=/data1 busybox sh $ podman run --mount type=bind,src=volume-name,target=/data1 busybox sh

When using SELinux, be aware that the host has no knowledge of container SELinux policy. Therefore, in the above example, if SELinux policy is enforced, the /var/db

directory is not writable to the container. A "Permission Denied" message will occur and an

avc:

message in the host's syslog.

To work around this, at time of writing this man page, the following command needs to be run in order for the proper SELinux policy type label to be attached to the host directory:

$ chcon -Rt svirt_sandbox_file_t /var/db

Now, writing to the /data1

volume in the container will be allowed and the changes will also be reflected on the host in

/var/db

Using alternative security labeling

Override the default labeling scheme for each container by specifying the --security-opt

flag. For example, specify the MCS/MLS level, a requirement for MLS systems. Specifying the level in the following command allows the same content to be shared between containers.

podman run --security-opt label=level:s0:c100,c200 -i -t fedora bash

An MLS example might be:

$ podman run --security-opt label=level:TopSecret -i -t rhel7 bash

To disable the security labeling for this container versus running with the

--permissive

flag, use the following command:

$ podman run --security-opt label=disable -i -t fedora bash

Tighten the security policy on the processes within a container by specifying an alternate type for the container. For example, run a container that is only allowed to listen on Apache ports by executing the following command:

$ podman run --security-opt label=type:svirt_apache_t -i -t centos bash

Note an SELinux policy defining a svirt_apache_t

type would need to be written.

To mask additional specific paths in the container, specify the paths separated by a colon using the mask

option with the

--security-opt

flag.

$ podman run --security-opt mask=/foo/bar:/second/path fedora bash

To unmask all the paths that are masked by default, set the unmask

option to

ALL

. Or to only unmask specific paths, specify the paths as shown above with the

mask

option.

$ podman run --security-opt unmask=ALL fedora bash

To unmask all the paths that start with /proc, set the unmask

option to

/proc/

$ podman run --security-opt unmask=/proc/* fedora bash

$ podman run --security-opt unmask=/foo/bar:/sys/firmware fedora bash

Setting device weight via --blkio-weight-device

flag.

$ podman run -it --blkio-weight-device "/dev/sda:200" ubuntu

Using a podman container with input from a pipe

$ echo "asdf" | podman run --rm -i --entrypoint /bin/cat someimage asdf

Setting automatic user namespace separated containers

# podman run --userns=auto:size=65536 ubi8-micro cat /proc/self/uid_map 0 2147483647 65536 # podman run --userns=auto:size=65536 ubi8-micro cat /proc/self/uid_map 0 2147549183 65536

Setting Namespaced Kernel Parameters (Sysctls)

The --sysctl

sets namespaced kernel parameters (sysctls) in the container. For example, to turn on IP forwarding in the containers network namespace, run this command:

$ podman run --sysctl net.ipv4.ip_forward=1 someimage

Note that not all sysctls are namespaced. Podman does not support changing sysctls inside of a container that also modify the host system. As the kernel evolves we expect to see more sysctls become namespaced.

See the definition of the --sysctl

option above for the current list of supported sysctls.

Set UID/GID mapping in a new user namespace

Running a container in a new user namespace requires a mapping of the uids and gids from the host.

$ podman run --uidmap 0:30000:7000 --gidmap 0:30000:7000 fedora echo hello

Configuring Storage Options from the command line

Podman allows for the configuration of storage by changing the values in the /etc/container/storage.conf

or by using global options. This shows how to set up and use fuse-overlayfs for a one-time run of busybox using global options.

podman --log-level=debug --storage-driver overlay --storage-opt "overlay.mount_program=/usr/bin/fuse-overlayfs" run busybox /bin/sh

Configure timezone in a container

$ podman run --tz=local alpine date $ podman run --tz=Asia/Shanghai alpine date $ podman run --tz=US/Eastern alpine date

Adding dependency containers

The first container, container1, is not started initially, but must be running before container2 will start. The

podman run

command will start the container automatically before starting container2.

$ podman create --name container1 -t -i fedora bash $ podman run --name container2 --requires container1 -t -i fedora bash

Multiple containers can be required.

$ podman create --name container1 -t -i fedora bash $ podman create --name container2 -t -i fedora bash $ podman run --name container3 --requires container1,container2 -t -i fedora bash

Configure keep supplemental groups for access to volume

$ podman run -v /var/lib/design:/var/lib/design --group-add keep-groups ubi8

Configure execution domain for containers using personality flag

$ podman run --name container1 --personality=LINUX32 fedora bash

Run a container with external rootfs mounted as an overlay

$ podman run --name container1 --rootfs /path/to/rootfs:O bash

Handling Timezones in java applications in a container.

In order to use a timezone other than UTC when running a Java application within a container, the

TZ

environment variable must be set within the container. Java applications will ignore the value set with the

--tz

option.

# Example run podman run -ti --rm -e TZ=EST mytzimage lrwxrwxrwx. 1 root root 29 Nov 3 08:51 /etc/localtime -> ../usr/share/zoneinfo/Etc/UTC Now with default timezone: Fri Nov 19 18:10:55 EST 2021 Java default sees the following timezone: 2021-11-19T18:10:55.651130-05:00 Forcing UTC: Fri Nov 19 23:10:55 UTC 2021

Run a container connected to two networks (called net1 and net2) with a static ip

$ podman run --network net1:ip=10.89.1.5 --network net2:ip=10.89.10.10 alpine ip addr

Rootless Containers

Podman runs as a non-root user on most systems. This feature requires that a new enough version of shadow-utils

be installed. The

shadow-utils

package must include the newuidmap(1) and newgidmap(1) executables.

In order for users to run rootless, there must be an entry for their username in /etc/subuid

and

/etc/subgid

which lists the UIDs for their user namespace.

Rootless Podman works better if the fuse-overlayfs and slirp4netns packages are installed. The fuse-overlayfs

package provides a userspace overlay storage driver, otherwise users need to use the

vfs

storage driver, which can be disk space expensive and less performant than other drivers.

To enable VPN on the container, slirp4netns or pasta needs to be specified; without either, containers need to be run with the --network=host flag.

ENVIRONMENT

Environment variables within containers can be set using multiple different options, in the following order of precedence (later entries override earlier entries):

• Container image: Any environment variables specified in the container image.

•

--http-proxy

: By default, several environment variables will be passed in from the host, such as

http_proxy

and

no_proxy

. See

--http-proxy

for details.

•

--env-host

: Host environment of the process executing Podman is added.

•

--env-file

: Any environment variables specified via env-files. If multiple files are specified, then they override each other in order of entry.

•

--env

: Any environment variables specified will override previous settings.

Run containers and set the environment ending with a *

. The trailing

glob functionality is only active when no value is specified:

$ export ENV1=a $ podman run --env 'ENV*' alpine env | grep ENV ENV1=a $ podman run --env 'ENV*=b' alpine env | grep ENV ENV*=b

CONMON

When Podman starts a container it actually executes the conmon program, which then executes the OCI Runtime. Conmon is the container monitor. It is a small program whose job is to watch the primary process of the container, and if the container dies, save the exit code. It also holds open the tty of the container, so that it can be attached to later. This is what allows Podman to run in detached mode (backgrounded), so Podman can exit but conmon continues to run. Each container has their own instance of conmon. Conmon waits for the container to exit, gathers and saves the exit code, and then launches a Podman process to complete the container cleanup, by shutting down the network and storage. For more information on conmon, please reference the conmon(8) man page.

FILES

/etc/subuid

/etc/subgid

NOTE: Use the environment variable

TMPDIR

to change the temporary storage location of downloaded container images. Podman defaults to use

/var/tmp