--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 matches 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 on Linux, and $HOME/.config/containers/auth.json on Windows/macOS. The file is created by 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 10 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 is created. If the path is not absolute, the path is considered to be relative to the cgroups path of the init process. Cgroups are created if they do not already exist.

--cgroupns=mode¶

Set the cgroup namespace mode for the container.

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 creates CGroups.

Default is enabled.

The enabled option creates a new cgroup under the cgroup-parent. The disabled option forces 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 is 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 is mounted into that location as well. Multiple directories are separated with a comma.

--cidfile=file¶

Write the container ID to file. The file is removed along with the container, except when used with podman --remote run on detached containers.

--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 is allowed to use that much CPU time until the CPU period ends (controllable via --cpu-period).

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-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 can 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=shares¶

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 only applies 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 varies 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 receives 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 C1 with --cpu-shares=1024 running two processes, this can result in the following division of CPU shares:

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.

--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 or --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).

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.

--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 only uses memory from the first two memory nodes.

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.

--decryption-key=key[:passphrase]¶

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

--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 r for read, w for write, and m for mknod(2).

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

Note: if host-device is a symbolic link then it is resolved first. The container only stores the major and minor numbers of the host device.

Podman may load kernel modules required for using the specified device. The devices that Podman loads 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 fails. 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 admin-guide/cgroup-v1/devices: - 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).

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.

--device-read-iops=path:rate¶

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

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.

--device-write-bps=path:rate¶

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

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.

--device-write-iops=path:rate¶

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

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.

--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 is used without changes.

This option cannot be combined with --network that is set to none or container:id.

--dns-option=option¶

Set custom DNS options. Invalid if using --dns-option with --network that is set to none or container:id.

--dns-search=domain¶

Set custom DNS search domains. Invalid if using --dns-search with --network that is set to none or container:id. 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 checks 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 searches the host environment for variables starting with the prefix and adds those variables to the container.

See ⟨#environment⟩ note below for precedence and examples.

--env-file=file¶

Read in a line-delimited file of environment variables.

See ⟨#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 is hello=world-some.

Please note that if the environment variable hello is not present in the image, then it'll be replaced by an empty string and so using --env-merge hello=${hello}-some would result in the new value of hello=-some, notice the leading - delimiter.

--expose=port[/protocol]¶

Expose a port or a range of ports (e.g. --expose=3300-3310). The protocol can be tcp, udp or sctp and if not given tcp is assumed. This option matches the EXPOSE instruction for image builds and has no effect on the actual networking rules unless -P/--publish-all is used to forward to all exposed ports from random host ports. To forward specific ports from the host into the container use the -p/--publish option instead.

--gidmap=[flags]container_uid:from_uid[: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 option cannot be called in conjunction with the --pod option as a gidmap cannot be set on the container level when in a pod.

--gpus=ENTRY¶

GPU devices to add to the container ('all' to pass all GPUs) Currently only Nvidia devices are supported.

--group-add=group | keep-groups¶

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

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)

--group-entry=ENTRY¶

Customize the entry that is written to the /etc/group file within the container when --user is used.

The variables $GROUPNAME, $GID, and $USERLIST are automatically replaced with their value at runtime if present.

--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 is interpreted as an argument to /bin/sh -c.

--health-interval=interval¶

Set an interval for the healthchecks. An interval of 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.

--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 0s.

Note: The health check command is executed as soon as a container is started, if the health check is successful the container's health state will be updated to healthy. However, if the health check fails, the health state will stay as starting until either the health check is successful or until the --health-start-period time is over. If the health check command fails after the --health-start-period time is over, the health state will be updated to unhealthy. The health check command is executed periodically based on the value of --health-interval.

--health-startup-cmd="command" | '["command", arg1 , ...]'¶

Set a startup healthcheck command for a container. This command is executed inside the container and is used to gate the regular healthcheck. When the startup command succeeds, the regular healthcheck begins and the startup healthcheck ceases. Optionally, if the command fails for a set number of attempts, the container is 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 of 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 is never restarted. The default is 0.

--health-startup-success=retries¶

The number of successful runs required before the startup healthcheck succeeds and the regular healthcheck begins. A value of 0 means that any success begins the regular healthcheck. The default is 0.

--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 is 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 does not use any proxy. Proxy environment variables specified for the container in any other way overrides the values that 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 uses 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.

--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 breaks container execution.

--init-ctr=type¶

(Pods only). When using pods, create an init style container, which is run after the infra container is started but before regular pod containers are started. Init containers are useful for running setup operations for the pod's applications.

Valid values for init-ctr type are always or once. The always value means the container runs with each and every pod start, whereas the once value means the container only runs once when the pod is started and then the container is removed.

Init containers are only run on pod start. Restarting a pod does not execute any init containers. Furthermore, init containers can only be created in a pod when that pod is not running.

--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:id. 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:id. 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.

--label, -l=key=value¶

Add metadata to a container.

--label-file=file¶

Read in a line-delimited file of labels.

--link-local-ip=ip¶

Not implemented.

--log-driver=driver¶

Logging driver for the container. Currently available options are k8s-file, journald, none, passthrough and passthrough-tty, with json-file aliased to k8s-file for scripting compatibility. (Default journald).

The podman info command below displays 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.

The passthrough-tty driver is the same as passthrough except that it also allows it to be used on a TTY if the user really wants it.

--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:id.

Remember that the MAC address in an Ethernet network must be unique. The IPv6 link-local address is 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 b (bytes), k (kibibytes), m (mebibytes), or g (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 is 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 b (bytes), k (kibibytes), m (mebibytes), or g (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 takes precedence. By default, memory reservation is 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 b (bytes), k (kibibytes), m (mebibytes), or g (gibibytes).

Must be used with the -m (--memory) flag. The argument value must be larger than that of
-m (--memory) By default, it is set to double the value of --memory.

Set number to -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, devpts, glob, image, ramfs, tmpfs and volume.

Options common to all mount types:

When source globs are specified without the destination directory, the files and directories are mounted with their complete path within the container. When the destination is specified, the files and directories matching the glob on the base file name on the destination directory are mounted. The option type=glob,src=/foo*,destination=/tmp/bar tells container engines to mount host files matching /foo* to the /tmp/bar/ directory in the container.

Options specific to type=volume:

Options specific to type=image:

Options specific to bind and glob:

Options specific to type=tmpfs and ramfs:

Options specific to type=devpts:

Examples:

--name=name¶

Assign a name to the container.

The operator can identify a container in three ways:

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

Invalid if using --dns, --dns-option, or --dns-search with --network set to none or container:id.

If used together with --pod, the container does 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 only has 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 manages /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 is 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 to 1000).

When running in rootless mode, the specified value can't be lower than the oom_score_adj for the current process. In this case, the oom-score-adj is clamped to the current process value.

--os=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 matches this OS, regardless of the host.

--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.

--pidfile=path¶

When the pidfile location is specified, the container process' PID is 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 is 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 matches this platform, regardless of the host.

--pod=name¶

Run container in an existing pod. Podman makes 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. When a container is run with a pod with an infra-container, the infra-container is started first.

--pod-id-file=file¶

Run container in an existing pod and read the pod's ID from the specified file. When a container is run within a pod which has an infra-container, the infra-container starts first.

--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\d+) 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. Due to the disabled security features, the privileged field should almost never be set as containers can easily break out of confinement.

Containers running in a user namespace (e.g., rootless containers) cannot have more privileges than the user 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 is bound on all IPs on the host.

By default, Podman publishes 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 is randomly assigned a port on the host.

Use podman port to see the actual mapping: podman port $CONTAINER $CONTAINERPORT.

Note that the network drivers macvlan and ipvlan do not support port forwarding, it will have no effect on these networks.

Note: If a container runs 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 - when there are a variety of containers in the pod, and programs in the container, all sharing a single interface and 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 makes the exposed port accessible on the host and the ports are available to any client that can reach the host.

When using this option, Podman binds 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.

--quiet, -q¶

Suppress output information when pulling images

--rdt-class=intel-rdt-class-of-service¶

Rdt-class sets the class of service (CLOS or COS) for the container to run in. Based on the Cache Allocation Technology (CAT) feature that is part of Intel's Resource Director Technology (RDT) feature set, all container processes will run within the pre-configured COS, representing a part of the cache. The COS has to be created and configured using a pseudo file system (usually mounted at /sys/fs/resctrl) that the resctrl kernel driver provides. Assigning the container to a COS requires root privileges and thus doesn't work in a rootless environment. Currently, the feature is only supported using runc as a runtime. See ⟨https://docs.kernel.org/arch/x86/resctrl.html⟩ for more details on creating a COS before a container can be assigned to it.

--read-only¶

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

By default, container root filesystems are writable, allowing processes to write files anywhere. By specifying the --read-only flag, the containers root filesystem are mounted read-only prohibiting any writes.

--read-only-tmpfs¶

When running --read-only containers, mount a read-write tmpfs on /dev, /dev/shm, /run, /tmp, and /var/tmp. The default is true.

When --read-only=true and --read-only-tmpfs=true additional tmpfs are mounted on the /tmp, /run, and /var/tmp directories.

When --read-only=true and --read-only-tmpfs=false /dev and /dev/shm are marked Read/Only and no tmpfs are mounted on /tmp, /run and /var/tmp. The directories are exposed from the underlying image, meaning they are read-only by default. This makes the container totally read-only. No writable directories exist within the container. In this mode writable directories need to be added via external volumes or mounts.

By default, when --read-only=false, the /dev and /dev/shm are read/write, and the /tmp, /run, and /var/tmp are read/write directories from the container image.

--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 is 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 does not take effect if a container is stopped via the podman kill or podman stop commands.

Valid policy values are:

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

When running containers in systemd services, use the restart functionality provided by systemd. In other words, do not use this option in a container unit, instead set the Restart= systemd directive in the [Service] section. See podman-systemd.unit(5) and systemd.service(5).

--retry=attempts¶

Number of times to retry pulling or pushing images between the registry and local storage in case of failure. Default is 3.

--retry-delay=duration¶

Duration of delay between retry attempts when pulling or pushing images between the registry and local storage in case of failure. The default is to start at two seconds and then exponentially back off. The delay is used when this value is set, and no exponential back off occurs.

--rm¶

Automatically remove the container and any anonymous unnamed volume associated with the container when it exits. 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 is the lower, and the container storage directory is 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.

idmap

If 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 #.

--sdnotify=container | conmon | healthy | 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 sets 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 healthy option sets MAINPID to conmon's pid, and sends READY when the container has turned healthy; requires a healthcheck to be set. 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 does not use it.

--seccomp-policy=policy¶

Specify the policy to select the seccomp profile. If set to image, Podman looks for a "io.containers.seccomp.profile" label in the container-image config and use its value as a seccomp profile. Otherwise, Podman follows 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 is not 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 is 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 affects the secret inside the container.

Secrets and its storage are managed using the podman secret command.

Secret Options

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

Note: Labeling can be disabled for all containers by setting label=false in the containers.conf (/etc/containers/containers.conf or $HOME/.config/containers/containers.conf) file.

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 b (bytes), k (kibibytes), m (mebibytes), or g (gibibytes). If the unit is omitted, the system uses bytes. If the size is omitted, the default is 64m. When size is 0, there is no limit on the amount of memory used for IPC by the container. This option conflicts with --ipc=host.

--shm-size-systemd=number[unit]¶

Size of systemd-specific tmpfs mounts such as /run, /run/lock, /var/log/journal and /tmp. A unit can be b (bytes), k (kibibytes), m (mebibytes), or g (gibibytes). If the unit is omitted, the system uses bytes. If the size is omitted, the default is 64m. When size is 0, the usage is limited to 50% of the host's available memory.

--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:

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.

Running the container in systemd mode causes the following changes:

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 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 is used. If set to false, TLS verification is not used. If not specified, TLS verification is used unless the target registry is listed as an insecure registry in containers-registries.conf(5)

--tmpfs=fs¶

Create a tmpfs mount.

Mount a temporary filesystem (tmpfs) mount into a container, for example:

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

This command mounts a tmpfs at /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 allocates 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 is only used when run interactively in a terminal. When feeding input to Podman, use -i only, not -it.

--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=[flags]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 possible values of the optional flags are discussed further down on this page. The amount value is optional and assumed to be 1 if not given.

The from_uid value is based upon the user running the command, either rootful or rootless users.

Rootful mappings

When podman create 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 is mapped. If for example amount is 4 the mapping looks like:

Rootless mappings

When podman create 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:

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 is 5 the second mapping step looks like:

When running as rootless, Podman uses 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:

Referencing a host ID from the parent namespace

As a rootless user, the given host ID in --uidmap or --gidmap is mapped from the intermediate namespace generated by Podman. Sometimes it is desirable to refer directly at the host namespace. It is possible to manually do so, by running podman unshare cat /proc/self/gid_map, finding the desired host id at the second column of the output, and getting the corresponding intermediate id from the first column.

Podman can perform all that by preceding the host id in the mapping with the @ symbol. For instance, by specifying --gidmap 100000:@2000:1, podman will look up the intermediate id corresponding to host id 2000 and it will map the found intermediate id to the container id 100000. The given host id must have been subordinated (otherwise it would not be mapped into the intermediate space in the first place).

If the length is greater than one, for instance with --gidmap 100000:@2000:2, Podman will map host ids 2000 and 2001 to 100000 and 100001, respectively, regardless of how the intermediate mapping is defined.

Extending previous mappings

Some mapping modifications may be cumbersome. For instance, a user starts with a mapping such as --gidmap="0:0:65000", that needs to be changed such as the parent id 1000 is mapped to container id 100000 instead, leaving container id 1 unassigned. The corresponding --gidmap becomes --gidmap="0:0:1" --gidmap="2:2:65534" --gidmap="100000:1:1".

This notation can be simplified using the + flag, that takes care of breaking previous mappings removing any conflicting assignment with the given mapping. The flag is given before the container id as follows: --gidmap="0:0:65000" --gidmap="+100000:1:1"

This notation leads to gaps in the assignment, so it may be convenient to fill those gaps afterwards: --gidmap="0:0:65000" --gidmap="+100000:1:1" --gidmap="1:65001:1"

One specific use case for this flag is in the context of rootless users. A rootless user may specify mappings with the + flag as in --gidmap="+100000:1:1". Podman will then "fill the gaps" starting from zero with all the remaining intermediate ids. This is convenient when a user wants to map a specific intermediate id to a container id, leaving the rest of subordinate ids to be mapped by Podman at will.

Passing only one of --uidmap or --gidmap

Usually, subordinated user and group ids are assigned simultaneously, and for any user the subordinated user ids match the subordinated group ids. For convenience, if only one of --uidmap or --gidmap is given, podman assumes the mapping refers to both UIDs and GIDs and applies the given mapping to both. If only one value of the two needs to be changed, the mappings should include the u or the g flags to specify that they only apply to UIDs or GIDs and should not be copied over.

For instance given the command

podman create --gidmap "0:0:1000" --gidmap "g2000:2000:1"

Since no --uidmap is given, the --gidmap is copied to --uidmap, giving a command equivalent to

podman create --gidmap "0:0:1000" --gidmap "2000:2000:1" --uidmap "0:0:1000"

The --gidmap "g2000:2000:1" used the g flag and therefore it was not copied to --uidmap.

Rootless mapping of additional host GIDs

A rootless user may desire to map a specific host group that has already been subordinated within /etc/subgid without specifying the rest of the mapping.

This can be done with --gidmap "+gcontainer_gid:@host_gid"

Where:

For instance, if a user belongs to the group 2000 and that group is subordinated to that user (with usermod --add-subgids 2000-2000 $USER), the user can map the group into the container with: --gidmap=+g100000:@2000.

If this mapping is combined with the option, --group-add=keep-groups, the process in the container will belong to group 100000, and files belonging to group 2000 in the host will appear as being owned by group 100000 inside the container.

podman run --group-add=keep-groups --gidmap="+g100000:@2000" ...

No subordinate UIDs

Even if a user does not have any subordinate UIDs in /etc/subuid, --uidmap can be used to map the normal UID of the user to a container UID by running podman create --uidmap $container_uid:0:1 --user $container_uid ....

Pods

The --uidmap option cannot be called in conjunction with the --pod option as a uidmap cannot be set on the container level when in a pod.

--ulimit=option¶

Ulimit options. Sets the ulimits values inside of the container.

--ulimit with a soft and hard limit in the format =[:]. For example:

$ podman run --ulimit nofile=1024:1024 --rm ubi9 ulimit -n 1024

Set -1 for the soft or hard limit to set the limit to the maximum limit of the current process. In rootful mode this is often unlimited.

Use host to copy the current configuration from the host.

Don't use nproc with the ulimit flag as Linux uses nproc to set the maximum number of processes available to a user, not to a container.

Use the --pids-limit option to modify the cgroup control to limit the number of processes within a container.

--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 runs 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 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 by default corresponds to the UID and GID of the user invoking Podman.

--userns=mode¶

Set the user namespace mode for the container.

If --userns is not set, the default value is determined as follows. - If --pod is set, --userns is ignored and the user namespace of the pod is used. - If the environment variable PODMAN_USERNS is set its value is used. - If userns is specified in containers.conf this value is used. - Otherwise, --userns=host is assumed.

--userns="" (i.e., an empty string) is an alias for --userns=host.

This option is incompatible with --gidmap, --uidmap, --subuidname and --subgidname.

Rootless user --userns=Key mappings:

Valid mode values are:

auto[:OPTIONS,...]: automatically create a unique user namespace.

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 option --userns=keep-id uses all the subuids and subgids of the user. The option --userns=nomap uses all the subuids and subgids of the user except the user's own ID. Using --userns=auto when starting new containers does not work as long as any containers exist that were started with --userns=keep-id or --userns=nomap.

Valid auto options:

The host UID and GID in gidmapping and uidmapping can optionally be prefixed with the @ symbol. In this case, podman will look up the intermediate ID corresponding to host ID and it will map the found intermediate ID to the container id. For details see --uidmap.

container:id: join the user namespace of the specified container.

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

keep-id: creates a user namespace where the current user's UID:GID are mapped to the same values in the container. For containers created by root, the current mapping is created into a new user namespace.

Valid keep-id options:

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:

--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 mounts the named volume from the host into the container. If no such named volume exists, Podman creates one. If no source is given, the volume is created as an anonymously named volume with a randomly generated name, and is 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 are mounted from the remote server, not necessarily the client machine.)

The OPTIONS is a comma-separated list and can be one or more of:

The CONTAINER-DIR must be an absolute path such as /src/docs. The volume is 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 returns an error. Users must pre-create the source files or directories.

Any source that does not begin with a . or / is treated as the name of a named volume. If a volume with that name does not exist, it is 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 or :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. If the volume has thousands of inodes, this process takes a long time, delaying the start of the container.

Warning use with caution since this modifies 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 or :Z to the volume mount. These suffixes tell Podman to relabel file objects on the shared volumes. The z 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 Z 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, if the volume has thousands of inodes, this process takes 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 -Rt 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 create --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 is the lower, and the container storage directory is 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 does not remove it on lifecycle completion. Example :O,upperdir=/some/upper,workdir=/some/work

Subsequent executions of the container sees 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.

Do not modify the source directory mounted into the container with an overlay mount, it can cause unexpected failures. Only modify the directory after the container finishes running.

Mounts propagation

By default, bind-mounted volumes are private. That means any mounts done inside the container are not visible on the host and vice versa. One can change this behavior by specifying a volume mount propagation property. When a volume is shared, mounts done under that volume inside the container are visible on host and vice versa. Making a volume slave[1] ⟨#Footnote1⟩ enables only one-way mount propagation: mounts done on the host under that volume are visible inside the container but not the other way around.

To control mount propagation property of a volume one can use the [r]shared, [r]slave, [r]private or the [r]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 is not 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 volumes with the nosuid options means that SUID executables on the volume can not be used by applications 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 can be executed within the container.

Mounting the volume with the nodev option means that no devices on the volume can 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 converts /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 fails.

Idmapped mount

If 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 or rw option.

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 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.

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 and newgidmap 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.