podman-pod-clone(1)
๐ธ podman-pod-clone(1) ๐ธ
okay so you found the General Commands Manual page for podman-pod-clone โ literally the "make me a twin" command. let's get into it bestie ๐
โจ NAME โจ
podman-pod-clone โ Create a copy of an existing pod ๐ซถ
โจ SYNOPSIS โจ
podman pod clone [options] pod name
โจ DESCRIPTION โจ
podman pod clone creates a copy of a pod โ it recreates the identical config for the pod and for all of its containers. that's the whole vibe. ๐
you can tweak stuff though: users can modify the pod's new name, and select pod details within the infra container. so it's a twin, but you get to dress it up. ๐
โจ OPTIONS โจ
--blkio-weight=weightโ Block IO relative weight. the weight is a value between 10 and 1000.
heads up: this option is not supported on cgroups V1 rootless systems. ๐ญ
--blkio-weight-device=device:weightโ Block IO relative device weight.--cgroup-parent=pathโ Path to cgroups under which the cgroup for the pod is created. if the path isn't absolute, it's considered relative to the cgroups path of the init process. Cgroups are created if they don't already exist. (they just show up, no questions asked โจ)--cpu-shares,-c=sharesโ 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 leftover CPU time. the actual amount of CPU time varies depending on the number of containers running on the system.
for example, consider three containers โ 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. math ate, honestly. ๐ฅ
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:
โโโโโโโฌโโโโโโโโโโโโฌโโโโโโฌโโโโโโโโโโโโโโโ
โ PID โ container โ CPU โ CPU share โ
โโโโโโโผโโโโโโโโโโโโผโโโโโโผโโโโโโโโโโโโโโโค
โ 100 โ C0 โ 0 โ 100% of CPU0 โ
โโโโโโโผโโโโโโโโโโโโผโโโโโโผโโโโโโโโโโโโโโโค
โ 101 โ C1 โ 1 โ 100% of CPU1 โ
โโโโโโโผโโโโโโโโโโโโผโโโโโโผโโโโโโโโโโโโโโโค
โ 102 โ C1 โ 2 โ 100% of CPU2 โ
โโโโโโโดโโโโโโโโโโโโดโโโโโโดโโโโโโโโโโโโโโโ
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
and yeah โ this option is not supported on cgroups V1 rootless systems. ๐
--cpusโ Set a number of CPUs for the pod that overrides the original pod's CPU limits. if none are specified, the original pod's Nano CPUs are used.--cpuset-cpus=numberโ 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.
if none are specified, the original pod's CPUset is used. ๐
--cpuset-mems=nodesโ 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 and then processes in the container only use 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.
--destroyโ Remove the original pod that we're cloning once it's been used to mimic the configuration. so like... the original is gone-gone. ๐--device=host-device[:container-device][:permissions]โ Add a host device to the pod. the format of this isHOST-DEVICE[:CONTAINER-DEVICE][:PERMISSIONS], whereHOST-DEVICEis the path of the device node on the host,CONTAINER-DEVICEis the path of the device node in the container, andPERMISSIONSis a list of permissions combining'r'for read,'w'for write, and'm'formknod(2).
example: --device=/dev/sdc:/dev/xvdc:rwm.
note: if host-device is a symbolic link then it is resolved first. the pod 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: the pod implements devices by storing the initial configuration passed by the user and recreating the device on each container added to the pod. (it re-commits every time, honestly iconic โจ)
--device-read-bps=path:rateโ 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-write-bps=path:rateโ 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.
--gidmap=container_gid:from_gid[:amount]โ Run all containers in the pod in a new user namespace using the supplied GID mapping. this option conflicts with the--usernsoption. it provides a way to map host GIDs to container GIDs. it can be passed several times to map different ranges. ๐--gpus=ENTRYโ Start the container with GPU support. whereENTRYcan beallto request all GPUs, or a vendor-specific identifier. currently, NVIDIA and AMD devices are supported. if both NVIDIA and AMD devices are present, the NVIDIA devices will be preferred, and a CDI device name must be specified using the--deviceflag to request a set of GPUs from a specific vendor. (NVIDIA said main character energy, sorry AMD ๐ญ)--help,-hโ Print usage statement.--hostname=nameโ Set the pod's hostname inside all containers.
the given hostname is also added to the /etc/hosts file using the container's primary IP address (also see the --add-host option).
--infra-command=commandโ The command that is run to start the infra container. Default:"/pause".--infra-conmon-pidfile=fileโ Write the pid of the infra container'sconmonprocess to a file. asconmonruns in a separate process than Podman, this is necessary when using systemd to manage Podman containers and pods.--infra-name=nameโ The name that is used for the pod's infra container.--label,-l=key=valueโ Add metadata to a pod. ๐ท๏ธ--label-file=fileโ Read in a line-delimited file of labels.--memory,-m=number[unit]โ Memory limit. a unit can beb(bytes),k(kibibytes),m(mebibytes), org(gibibytes).
allows the memory available to a container to be constrained. if the host supports swap memory, then the --memory memory setting can be larger than physical RAM. if a limit of 0 is specified (not using --memory), 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). millions of trillions, bestie. ๐คฏ
this option is not supported on cgroups V1 rootless systems.
--memory-swap=number[unit]โ A limit value equal to memory plus swap. a unit can beb(bytes),k(kibibytes),m(mebibytes), org(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. โพ๏ธ
this option is not supported on cgroups V1 rootless systems.
--name,-nโ Set a custom name for the cloned pod. the default if not specified is of the syntax:<ORIGINAL_NAME>-clone. cute, right? ๐--pid=pidโ Set the PID mode for the pod. the default is to create a private PID namespace for the pod. requires the PID namespace to be shared via--share.host: use the host's PID namespace for the podns: join the specified PID namespaceprivate: create a new namespace for the pod (default)
--restart=policyโ Restart policy to follow when containers exit. the restart policy does not take effect if a container is stopped via thepodman killorpodman stopcommands. ๐
valid policy values are:
no: Do not restart containers on exitnever: Synonym forno; do not restart containers on exiton-failure[:max_retries]: Restart containers when they exit with a non-zero exit code, retrying indefinitely or until the optionalmax_retriescount is hitalways: Restart containers when they exit, regardless of status, retrying indefinitely
unless-stoppedโ restarts containers when they exit, unless the container was explicitly stopped by the user. After a system reboot, containers with this policy get restarted bypodman-restart.serviceonly if they were not explicitly stopped by the user before the reboot. This is the difference fromalways, which restarts containers after a system reboot regardless of whether they were user-stopped ๐
Podman ships a systemd unit file, podman-restart.service, which restarts containers after a system reboot. ๐ซถ
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). โจ
Default restart policy for all the containers in a pod.
--security-opt=optionโ security options, bestie ๐ก๏ธapparmor=unconfinedโ turn off apparmor confinement for the podapparmor=alternate-profileโ set the apparmor confinement profile for the podlabel=user:USERโ set the label user for the pod processeslabel=role:ROLEโ set the label role for the pod processeslabel=type:TYPEโ set the label process type for the pod processeslabel=level:LEVELโ set the label level for the pod processeslabel=filetype:TYPEโ set the label file type for the pod fileslabel=disableโ turn off label separation for the pod
Note: labeling can be disabled for all pods/containers by settinglabel=falsein thecontainers.conf(/etc/containers/containers.confor$HOME/.config/containers/containers.conf) file. ๐
label=nestedโ allows SELinux modifications within the container. Containers are allowed to modify SELinux labels on files and processes, as long as SELinux policy allows. Withoutnested, containers view SELinux as disabled, even when it is enabled on the host. Containers are prevented from setting any labels.mask=/path/1:/path/2โ the paths to mask, separated by a colon. A masked path cannot be accessed inside the containers within the pod. ๐no-new-privilegesโ disables container processes from gaining additional privileges through theexecve(2)system call (e.g. via setuid or setgid bits, or via file capabilities). Programs that rely on setuid/setgid bits set on their executable to change user id or group id are no longer able to do so, and any file capabilities added to the executable (e.g. viasetcap) are not added to the permitted capability set. For more details, see: https://docs.kernel.org/userspace-api/no_new_privs.html.seccomp=unconfinedโ turn off seccomp confinement for the pod.seccomp=profile.jsonโ JSON file to be used as a seccomp filter. Note that theio.podman.annotations.seccompannotation is set with the specified value as shown inpodman inspect. ๐proc-opts=OPTIONSโ comma-separated list of options to use for the/procmount. More details for the possible mount options are specified in theproc(5)man page.unmask=ALLor/path/1:/path/2, or shell expanded paths (/proc/*) โ paths to unmask, separated by a colon. If set toALL, it unmasks 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,/sys/devices/virtual/powercap. 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 settinglabel=falsein thecontainers.conf(5)file. ๐
--shm-size=number[unit]โ size of/dev/shm. The unit can beb(bytes),k(kibibytes),m(mebibytes), org(gibibytes). If the unit is omitted, the system uses bytes. If the size is omitted, the default is64m. When size is0, there is no limit on the amount of memory used for IPC by the pod. ๐ซง This option conflicts with--ipc=host.--shm-size-systemd=number[unit]โ size of systemd-specific tmpfs mounts such as/run,/run/lock,/var/log/journaland/tmp. The unit can beb(bytes),k(kibibytes),m(mebibytes), org(gibibytes). If the unit is omitted, the system uses bytes. If the size is omitted, the default is64m. When size is0, the usage is limited to 50% of the host's available memory. ๐ธ--startโ when set to true, this flag starts the newly created pod after the clone process has completed. All containers within the pod are started. ๐--subgidname=nameโ run the container in a new user namespace using the map with name in the/etc/subgidfile. When running rootless, the user needs the necessary permissions to use the mapping. Seesubgid(5). This flag conflicts with--usernsand--gidmap. Together with--gidmapit acts as if--gidmapwas passed with all mappings of the name group in/etc/subgid.--subuidname=nameโ run the container in a new user namespace using the map with name in the/etc/subuidfile. When running rootless, the user needs the necessary permissions to use the mapping. Seesubuid(5). This flag conflicts with--usernsand--uidmap. Together with--uidmapit acts as if--uidmapwas passed with all mappings of the name user in/etc/subuid.--sysctl=name=valueโ configure namespaced kernel parameters for all containers in the pod. ๐ง
For the IPC namespace, the following sysctls are allowed:
kernel.msgmaxkernel.msgmnbkernel.msgmnikernel.semkernel.shmallkernel.shmmaxkernel.shmmnikernel.shm_rmid_forced- Sysctls beginning with
fs.mqueue.*
Note: if the ipc namespace is not shared within the pod, the above sysctls are not allowed. ๐
For the network namespace, only sysctls beginning with net.* are allowed.
Note: if the network namespace is not shared within the pod, the above sysctls are not allowed. ๐
--uidmap=container_uid:from_uid[:amount]โ run all containers in the pod in a new user namespace using the supplied mapping. This option conflicts with the--usernsand--subuidnameoptions. This option provides a way to map host UIDs to container UIDs. It can be passed several times to map different ranges. ๐ฅ--userns=modeโ set the user namespace mode for all the containers in a pod. It defaults to thePODMAN_USERNSenvironment variable. An empty value ("") means user namespaces are disabled. ๐
Rootless user --userns=Key mappings โ here's the tea, key by key:
""โ Host User$UID, Container User0(Default User account mapped to root user in container.)hostโ Host User$UID, Container User0(Default User account mapped to root user in container.)keep-idโ Host User$UID, Container User$UID(Map user account to same UID within container.)autoโ Host User$UID, Container User nil (Host User UID is not mapped into container.)nomapโ Host User$UID, Container User nil (Host User UID is not mapped into container.)
Valid mode values are: โจ
auto[:OPTIONS,...]โ automatically create a namespace. It is possible to specify these options toauto:gidmapping=CONTAINER_GID:HOST_GID:SIZEto 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,autoestimates the size for the user namespace.uidmapping=CONTAINER_UID:HOST_UID:SIZEto force a UID mapping to be present in the user namespace.
hostโ 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 (default).keep-idโ 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.nomapโ 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.
--uts=modeโ set the UTS namespace mode for the pod. The following values are supported: ๐ฆhostโ use the host's UTS namespace inside the pod.privateโ create a new namespace for the pod (default).ns:[path]โ run the pod in the given existing UTS namespace.
--volume,-v=[[SOURCE-VOLUME|HOST-DIR:]CONTAINER-DIR[:OPTIONS]]โ create a bind mount. ๐
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. The nocreate option can be used to disable this behavior and require the volume to already exist. If no source is given, the volume is created as an anonymously named volume with a randomly generated name, and is removed when the pod is removed via the --rm flag or the podman rm --volumes command. ๐
(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:
rw|roz|Z[O][U][no]copy
[no]dev[no]exec[no]suid[r]bind[r]shared|[r]slave|[r]private[r]unbindable[1]idmap[=options]nocreate
CONTAINER-DIR has to be an absolute path, like /src/docs โ that's the directory the volume gets mounted at inside the container. No relative shenanigans, bestie. ๐
If you specify a volume source, it's either a path on the host or the name of a named volume. Host paths can be absolute or relative; relative ones get resolved relative to the directory Podman is run in. If the source doesn't exist, Podman returns an error โ so pre-create those source files or directories yourself, mkay? ๐ซถ
Anything that doesn't start with a . or a / gets treated as the name of a named volume. If a volume with that name doesn't exist, it gets created. Volumes created by name are not anonymous, and they are not removed by the --rm option or by the podman rm --volumes command. Iconic, but also a heads-up. ๐
The nocreate option can be specified for named volumes to prevent automatic volume creation. If nocreate is set and the volume does not exist, Podman returns an error instead of creating it. Super useful when you want to guarantee a volume was explicitly created before it gets used. โ
$ podman pod clone -v myvolume:/data:nocreate alpine
Specify multiple -v options to mount one or more volumes into a pod. Stack 'em. ๐ง
โจ Write Protected Volume Mounts โจ
Add the :ro or :rw option to mount a volume read-only or read-write, respectively. By default, volumes are mounted read-write. See examples. ๐
๐ Chowning Volume Mounts ๐
When a named volume is first mounted to a container, Podman automatically adjusts the ownership of the volume's mount point during container initialization. This chown operation happens under these conditions, bestie:
- The volume was not used yet (has
NeedsChownset totrue) - The volume is empty or has not been copied up yet
- The volume is not managed by an external volume driver
- The volume driver is not
"image"
For volumes with idmapped mounts (using the idmap option), the ownership change takes into account the container's user namespace mappings, but the idmapped volume retains proper UID/GID mapping. For volumes without idmapping, the mount point gets chowned to match the container's process user and group, mapped to the host user namespace if user namespace remapping is enabled. ๐
If a pod is created in a new user namespace, the UID and GID in the container may correspond to a different UID and GID on the host. Yes, that's the whole point, and yes, it's a lot. ๐ญ
The :U suffix tells Podman to use the correct host UID and GID based on the UID and GID within the pod, to recursively change 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 pod. Fr fr, it's slow.
โ ๏ธ Warning: use with caution, since this modifies the host filesystem. Your host. The actual host. Be so careful. ๐
๐ธ Labeling Volume Mounts ๐ธ
Labeling systems like SELinux require that proper labels are placed on volume content mounted into a pod. Without a label, the security system might prevent the processes running inside the pod from using the content. By default, Podman does not change the labels set by the OS. Respect the OS. โจ
To change a label in the pod 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 pods 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 โ only the current pod can use a private volume. ๐
Note: all containers within a pod share the same SELinux label. This means all containers within said pod can read/write volumes shared into the container created with the:Zon any one of the containers. 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 pod. If the volume was previously relabeled with thezoption, Podman is optimized to not relabel a second time. If files are moved into the volume, then the labels can be manually changed with thechcon -Rt container_file_t PATHcommand. ๐ท๏ธ
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 pod. For example, if a user wanted to volume mount their entire home directory into a pod, they need to disable SELinux separation. ๐
$ podman pod clone --security-opt label=disable -v $HOME:/home/user fedora touch /home/user/file
๐ฆ Overlay Volume Mounts ๐ฆ
The :O flag tells Podman to mount the directory from the host as temporary storage using the overlay file system. The pod 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 pod finishes executing โ similar to a tmpfs mount point being unmounted. Poof. Gone. ๐ซง
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 see the original source directory content โ any changes from previous pod executions no longer exist. Reset era. ๐
One use case of the overlay mount is sharing the package cache from the host into the container to allow speeding up builds. We love a build speedup. โก
Note: the O flag conflicts with other options listed above. Pick a lane.
Content mounted into the container is labeled with the private label. On SELinux systems, labels in the source directory must be readable by the pod infra 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 pod or infra container to work. ๐ฎโ๐จ
Do not modify the source directory mounted into the pod with an overlay mount โ it can cause unexpected failures. Only modify the directory after the container finishes running. Please. For me. ๐
๐ Mounts propagation ๐
By default, bind-mounted volumes are private. That means any mounts done inside the pod are not visible on the host, and vice versa โ nothing leaks either way. One can change this behavior by specifying a volume mount propagation property. When a volume is shared, mounts done under that volume inside the pod are visible on the host and vice versa. Making a volume slave [1] 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. One-way street, no cap. ๐ฃ๏ธ
To control the 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 the 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] ๐ง
To recursively mount a volume and all of its submounts into a pod, use the rbind option. By default the bind option is used, and submounts of the source directory are not mounted into the pod. ๐ฆ
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. ๐
Mounting volumes with the nosuid option means that SUID executables on the volume cannot be used by applications to change their privilege. By default, volumes are mounted with nosuid. ๐
Mounting the volume with the noexec option means that no executables on the volume can be executed within the pod. ๐ซ
Mounting the volume with the nodev option means that no devices on the volume can be used by processes within the pod. By default, volumes are mounted with nodev. ๐ซ
If the HOST-DIR is a mount point, then dev, suid, and exec options are ignored by the kernel. The kernel said no. ๐
Use df HOST-DIR to figure out the source mount, then use findmnt -o TARGET,PROPAGATION source-mount-dir to figure out the propagation properties of the source mount. If the 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 the mount is a slave, and if nothing is there, the mount is private. [1] ๐
To change propagation properties of a mount point, use the 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 the source mount. Say / is the source mount for /foo, then use mount --make-shared / to convert / into a shared mount. Slay. ๐ง
Note: if the user only has access rights via a group, accessing the volume from inside a rootless pod fails. Group access alone won't save you, sorry bestie. ๐ญ
๐ซ Idmapped mount ๐ซ
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 this:
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 #. Math, but make it mounts. ๐งฎโจ
--volumes-from=CONTAINER[:OPTIONS]โ Mount volumes from the specified container(s). Used to share volumes between containers and pods. Theoptionsis a comma-separated list with the following available elements:rw|roz
okay so this next bit is all about mounting already mounted volumes from a source container onto another pod, bestie. 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 โ iconic, honestly.
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. Easy.
Labeling systems like SELinux require that proper labels are placed on volume content mounted into a pod. 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. So yeah, labels matter ๐ .
To change a label in the pod 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. Slay.
If the location of the volume from the source container overlaps with data residing on a target pod, then the volume hides that data on the target. Lowkey important, so donโt forget it ๐ซถ.
โจ EXAMPLES โจ
Clone the specified pod to a new pod. Look at that shiny new ID:
# podman pod clone pod-name
6b2c73ff8a1982828c9ae2092954bcd59836a131960f7e05221af9df5939c584
Clone the specified pod to a new pod with a new name. Two IDs, because weโre extra:
# podman pod clone pod-name --name=cloned-pod
d0cf1f782e2ed67e8c0050ff92df865a039186237a4df24d7acba5b1fa8cc6e7
6b2c73ff8a1982828c9ae2092954bcd59836a131960f7e05221af9df5939c584
Clone and remove the specified pod to a new pod, modifying its cpus. Destroy-and-clone energy:
# podman pod clone --destroy --cpus=5 d0cf1
6b2c73ff8a1982828c9ae2092954bcd59836a131960f7e05221af9df5939c584
Clone the specified pod to a new named pod:
# podman pod clone 2d4d4fca7219b4437e0d74fcdc272c4f031426a6eacd207372691207079551de new_name
5a9b7851013d326aa4ac4565726765901b3ecc01fcbc0f237bc7fd95588a24f9
Clone a pod with memory limits:
# podman pod clone --memory=1g --memory-swap=2g pod-name
6b2c73ff8a1982828c9ae2092954bcd59836a131960f7e05221af9df5939c584
Clone a pod with CPU limits:
# podman pod clone --cpus=2.5 --cpu-shares=1024 pod-name
6b2c73ff8a1982828c9ae2092954bcd59836a131960f7e05221af9df5939c584
๐ธ SEE ALSO ๐ธ
podman-pod-create(1) โ go say hi if youโre making pods, iykyk.
๐ HISTORY ๐
May 2022, originally written by Charlie Doern cdoern@redhat.com โจmailto:cdoern@redhat.comโฉ. Respect the lore โจ.
๐ FOOTNOTES ๐
1: The Podman project is committed to inclusivity, a core value of open source. The master and slave mount propagation terminology used here is problematic and divisive, and needs to be changed. However, these terms are currently used within the Linux kernel and must be used as-is at this time. When the kernel maintainers rectify this usage, Podman will follow suit immediately. Real talk ๐ซถ.
thatโs the whole page, bestie โ source/version podman-pod-clone(1), dated May 2022. mwah ๐
๐ฆ where this page comes from
- arch rolling: podman 6.1.4-1 ยท Apache-2.0
- centos-stream 10: podman 7:6.1.0-2.el10 ยท Apache-2.0 AND BSD-2-Clause AND BSD-3-Clause AND ISC AND MIT AND MPL-2.0
- nixpkgs unstable: podman 6.1.4
- ๐ girlified by deepseek-ai/DeepSeek-V4.1-Flash-1017 on : a language model's rewrite of the original, under its terms