podman-pod-create(1)

NAME
podman-pod-create - Create a new pod

SYNOPSIS
podman pod create [options] [name]

DESCRIPTION
Creates an empty pod, or unit of multiple containers, and prepares it to have containers added to it. The pod can be created with a specific name. If a name is not given a random name is generated. The pod ID is printed to STDOUT. You can then use podman create --pod <pod_id|pod_name> ... to add containers to the pod, and podman pod start <pod_id|pod_name> to start the pod.

The operator can identify a pod in three ways: UUID long identifier (“f78375b1c487e03c9438c729345e54db9d20cfa2ac1fc3494b6eb60872e74778”) UUID short identifier (“f78375b1c487”) Name (“jonah”)

podman generates a UUID for each pod, and if a name is not assigned to the container with --name then a random string name is generated for it. This name is useful to identify a pod.

Note: resource limit related flags work by setting the limits explicitly in the pod's cgroup parent for all containers joining the pod. A container can override the resource limits when joining a pod. For example, if a pod was created via podman pod create --cpus=5, specifying podman container create --pod=<pod_id|pod_name> --cpus=4 causes the container to use the smaller limit. Also, containers which specify their own cgroup, such as --cgroupns=host, do NOT get the assigned pod level cgroup resources.

OPTIONS

  --add-host=hostname[;hostname[;...]]:ip
Add a custom host-to-IP mapping to the pod's /etc/hosts file.

The option takes one or multiple semicolon-separated hostnames to be mapped to a single IPv4 or IPv6 address, separated by a colon. It can also be used to overwrite the IP addresses of hostnames Podman adds to /etc/hosts by default (also see the --name and --hostname options). This option can be specified multiple times to add additional mappings to /etc/hosts. It conflicts with the --no-hosts option and conflicts with no_hosts=true in containers.conf.

Instead of an IP address, the special flag host-gateway can be given. This resolves to an IP address the container can use to connect to the host. The IP address chosen depends on your network setup, thus there's no guarantee that Podman can determine the host-gateway address automatically, which will then cause Podman to fail with an error message. You can overwrite this IP address using the host_containers_internal_ip option in containers.conf.

The host-gateway address is also used by Podman to automatically add the host.containers.internal and host.docker.internal hostnames to /etc/hosts. You can prevent that by either giving the --no-hosts option, or by setting host_containers_internal_ip="none" in containers.conf. If no host-gateway address was configured manually and Podman fails to determine the IP address automatically, Podman will silently skip adding these internal hostnames to /etc/hosts. If Podman is running in a virtual machine using podman machine (this includes Mac and Windows hosts), Podman will silently skip adding the internal hostnames to /etc/hosts, unless an IP address was configured manually; the internal hostnames are resolved by the gvproxy DNS resolver instead.

Podman will use the /etc/hosts file of the host as a basis by default, i.e. any hostname present in this file will also be present in the /etc/hosts file of the container. A different base file can be configured using the base_hosts_file config in containers.conf.

The /etc/hosts file is shared between all containers in the pod.

  --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.

  --cgroup-parent=path
Path to cgroups under which the cgroup for the pod 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.

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

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=amount
Set the total number of CPUs delegated to the pod. Default is 0.000 which indicates that there is no limit on computation power.

  --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.

  --device=host-device[:container-device][:permissions]
Add a host device to the pod. The format of this is HOST-DEVICE[:CONTAINER-DEVICE][:PERMISSIONS], where HOST-DEVICE is the path of the device node on the host, CONTAINER-DEVICE is the path of the device node in the container, and PERMISSIONS is a list of permissions 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 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.

  --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-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.

  --dns=ipaddr
Set custom DNS servers in the /etc/resolv.conf file that is shared between all containers in the pod. A special option, "none" is allowed which disables creation of /etc/resolv.conf for the pod.

  --dns-option=option
Set custom DNS options in the /etc/resolv.conf file that is shared between all containers in the pod.

  --dns-search=domain
Set custom DNS search domains in the /etc/resolv.conf file that is shared between all containers in the pod.

  --exit-policy=continue | stop
Set the exit policy of the pod when the last container exits. Supported policies are:
Exit Policy | Description
continue | The pod continues running, by keeping its infra container alive, when the last container exits. Used by default.
stop | The pod (including its infra container) is stopped when the last container exits. Used in kube play and quadlets.

  --gidmap=container_gid:from_gid[:amount]
Run all containers in the pod in a new user namespace using the supplied GID mapping. This option conflicts with the --userns option. It provides a way to map host GIDs to container GIDs. It can be passed several times to map different ranges.

  --gpus=ENTRY
Start the container with GPU support. Where ENTRY can be all to 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 --device flag to request a set of GPUs from a specific vendor.

  --help, -h
Print usage statement.

  --hostname=name
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).

  --hosts-file=path | none | image
Base file to create the /etc/hosts file inside the container. This must either be an absolute path to a file on the host system, or one of the following special flags:
  "" Follow the base_hosts_file configuration in containers.conf (the default)
  none Do not use a base file (i.e. start with an empty file)
  image Use the container image's /etc/hosts file as base file

  --infra
Create an infra container and associate it with the pod. An infra container is a lightweight container used to coordinate the shared kernel namespace of a pod. Default: true.

  --infra-command=command
The command that is run to start the infra container. Default: "/pause".

  --infra-conmon-pidfile=file
Write the pid of the infra container's conmon process to a file. As conmon runs in a separate process than Podman, this is necessary when using systemd to manage Podman containers and pods.

  --infra-image=image
The custom image that is used for the infra container. Unless specified, Podman builds a custom local image which does not require pulling down an image.

  --infra-name=name
The name that is used for the pod's infra container.

  --ip=IPv4
Specify a static IPv4 address for the pod, for example 10.88.64.128. This option can only be used if the pod is joined to only a single network - i.e., --network=network-name is used at most once - and if the pod 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 pod, use the --network option with multiple comma-separated ip values:
    --network mynet:ip=10.88.0.10,ip=10.88.0.11,ip=10.88.0.12

This assigns multiple static IPv4 addresses (10.88.0.10, 10.88.0.11, 10.88.0.12) to the same network interface.

Multi-Subnet Networks: When a network has multiple subnets, you can assign IPs from different subnets to the same pod. The IPs will be applied to a single network interface, with the first IP as primary and additional IPs as secondary addresses.

IP Assignment Order: For multi-subnet networks, IPs are grouped and ordered by their corresponding subnet, following the order in which subnets were defined during network creation (via --subnet flags). The order you specify IPs in the command does not affect the final assignment order. For example:
    podman network create --subnet 10.89.0.0/24 --subnet 10.90.0.0/24 mynet
    podman run --network mynet:ip=10.90.0.20,ip=10.89.0.10,ip=10.89.0.11 alpine

Results in IPs ordered by subnet: 10.89.0.10 (primary), 10.89.0.11 (secondary), 10.90.0.20 (secondary), since 10.89.0.0/24 was defined first.

Dynamic Allocation: If fewer IPs are specified than available subnets, the remaining subnets will receive dynamically allocated IPs. Dynamic IPs are assigned in subnet order after all static IPs are applied.

Example with multi-subnet network:
    podman network create --subnet 10.89.0.0/24 --subnet 10.90.0.0/24 mynet
    podman run --network mynet:ip=10.89.0.10,ip=10.90.0.20 alpine

This configures eth0 with 10.89.0.10 (primary) and 10.90.0.20 (secondary).

  --ip6=IPv6
Specify a static IPv6 address for the pod, for example fd46:db93:aa76:ac37::10. This option can only be used if the pod is joined to only a single network - i.e., --network=network-name is used at most once - and if the pod 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 pod, set multiple networks using the **--network option with a static IPv6 address specified for each using the ip6 mode for that option.

  --label, -l=key=value
Add metadata to a pod.

  --label-file=file
Read in a line-delimited file of labels.

  --mac-address=address
Pod network interface MAC address (e.g. 92:d0:c6:0a:29:33) This option can only be used if the pod is joined to only a single network - i.e., --network=network-name is used at most once - and if the pod 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 pod, 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 --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).

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.

  --name, -n=name
Assign a name to the pod.

  --network=mode, --net
Set the network mode for the pod.

Valid mode values are:

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

    •   alias=name: Add network-scoped alias for the container.

    •   ip=IPv4: Specify a static IPv4 address for this container.

    •   ip6=IPv6: Specify a static IPv6 address for this container.

    •   mac=MAC: Specify a static MAC address for this container.

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

    •   host_interface_name=name: Specify a name for the created network interface outside the container.

    Any other options will be passed through to netavark without validation. This can be useful to pass arguments to netavark plugins. For rootless bridge networks, port forwarding uses rootlessport by default. Setting rootless_port_forwarder="pasta" in the [network] section of containers.conf(5) switches to pasta's kernel-level forwarding (via pesto), which preserves the original client source IP address inside the container. This option is experimental and its behavior is subject to change. For example, to set a static IPv4 address and a static mac address, use --network bridge:ip=10.88.0.10,mac=44:33:22:11:00:99.

•   <network name or ID>[:OPTIONS,...]: Connect to a user-defined network; this is the network name or ID from a network created by podman network create. It is possible to specify the same options described under the bridge mode above. Use the --network option multiple times to specify additional networks.
    For backwards compatibility it is also possible to specify comma-separated networks on the first --network argument, however this prevents you from using the options described under the bridge section above.

•   none: Create a network namespace for the container but do not configure network interfaces for it, thus the container has no network connectivity.

•   container:id: Reuse another container's network stack.

•   host: Use the host's network namespace for the container instead of creating an isolated namespace. Warning: This gives the container full access to abstract Unix domain sockets and to TCP/UDP sockets bound to localhost. Since these mechanisms are often used to prevent access to sensitive system services, isolating them from access by external entities, use of this option may be considered a security vulnerability.

•   ns:path: Path to a network namespace to join.

•   private: Create a new namespace for the container. This uses the bridge mode for rootful containers and pasta for rootless ones.

•   pasta[:OPTIONS,...]: use pasta(1) to create a user-mode networking stack.
    This is the default for rootless containers and only supported in rootless mode.
    By default, IPv4 and IPv6 addresses and routes, as well as the pod interface name, are copied from the host. Port forwarding preserves the original source IP address. Options described in pasta(1) can be specified as comma-separated arguments.
    In terms of pasta(1) options, --config-net is given by default, in order to configure networking when the container is started, and --no-map-gw is also assumed by default, to avoid direct access from container to host using the gateway address. The latter can be overridden by passing --map-gw in the pasta-specific options (despite not being an actual pasta(1) option).
    For better integration with DNS handling, --dns-forward 169.254.1.1 is passed by default, and this address is added to resolv.conf(5) as first resolver. It is possible to pass --dns-forward explicitly in case a different IP address should be used.
    To make the host.containers.internal /etc/hosts entry work and allow connections to the host, --map-guest-addr 169.254.1.2 is passed by default. Again, it can be set explicitly to choose a different IP address.
    Also, -t none and -u none are passed if, respectively, no TCP or UDP port forwarding from host to container is configured (via Podman's --publish or by passing the pasta -t/-u options directly), to disable automatic port forwarding based on bound ports. Similarly, -T none and -U none are given to disable the same functionality from container to host.
    All options can also be set in containers.conf(5); see the pasta_options key under the network section in that file.
    Some examples:

    •   pasta:--map-gw: Allow the container to directly reach the host using the gateway address.

    •   pasta:--mtu,1500: Specify a 1500 bytes MTU for the tap interface in the container.

    •   pasta:--ipv4-only,-a,10.0.2.0,-n,24,-g,10.0.2.2,--dns-forward,10.0.2.3,-m,1500,--no-ndp,--no-dhcpv6,--no-dhcp: disable IPv6, assign 10.0.2.0/24 to the tap0 interface in the container, with gateway 10.0.2.3, enable DNS forwarder reachable at 10.0.2.3, set MTU to 1500 bytes, disable NDP, DHCPv6 and DHCP support.

    •   pasta:-I,tap0,--ipv4-only,-a,10.0.2.0,-n,24,-g,10.0.2.2,--dns-forward,10.0.2.3,--no-ndp,--no-dhcpv6,--no-dhcp: same as above, but leave the MTU to 65520 bytes

    •   pasta:-t,auto,-u,auto,-T,auto,-U,auto: enable automatic port forwarding based on observed bound ports from both host and container sides

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

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

  --network-alias=alias
Add a network-scoped alias for the pod, 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.

  --no-hostname
Do not create the /etc/hostname file in the containers.

By default, Podman manages the /etc/hostname file, adding the container's own hostname. When the --no-hostname option is set, the image's /etc/hostname will be preserved unmodified if it exists.

  --no-hosts
Do not modify the /etc/hosts file in the pod.

Podman assumes control over the pod's /etc/hosts file by default and adds entries for the container's name (see --name option) and hostname (see --hostname option), the internal host.containers.internal and host.docker.internal hosts, as well as any hostname added using the --add-host option. Refer to the --add-host option for details. Passing --no-hosts disables this, so that the image's /etc/hosts file is kept unmodified. The same can be achieved globally by setting no_hosts=true in containers.conf.

This option conflicts with --add-host.

  --pid=pid
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 pod
    ns: join the specified PID namespace
    private: create a new namespace for the pod (default)

  --pod-id-file=path
Write the pod ID to the file.

  --publish, -p=[[ip:][hostPort]:]containerPort[/protocol]
Publish a container's port, or range of ports, within this pod 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.

Port publishing is only supported for containers utilizing their own network namespace through bridge networks, or the pasta network mode.

For rootless bridge networks, port forwarding uses rootlessport by default, which is a userspace proxy that does not preserve client source IPs. Setting rootless_port_forwarder="pasta" in the [network] section of containers.conf(5) switches to pasta's kernel-level forwarding via pesto, preserving the original client IP address inside the container. This option is experimental and its behavior is subject to change.

Note: You must not publish ports of containers in the pod individually, but only by the pod itself.

Note: This cannot be modified once the pod is created.

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

  --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:

•   no : Do not restart containers on exit

•   never : Synonym for no; do not restart containers on exit

•   on-failure[:max_retries] : Restart containers when they exit with a non-zero exit code, retrying indefinitely or until the optional max_retries count is hit

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

•   unless-stopped : Restart containers when they exit, unless the container was explicitly stopped by the user. After a system reboot, containers with this policy will be restarted by podman-restart.service only if they were not explicitly stopped by the user before the reboot. This differs from always, which restarts containers after a system reboot regardless of whether they were user-stopped

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).

Default restart policy for all the containers in a pod.

  --security-opt=option
Security Options

•   apparmor=unconfined : Turn off apparmor confinement for the pod

•   apparmor=alternate-profile : Set the apparmor confinement profile for the pod

•   label=user:USER: Set the label user for the pod processes

•   label=role:ROLE: Set the label role for the pod processes

•   label=type:TYPE: Set the label process type for the pod processes

•   label=level:LEVEL: Set the label level for the pod processes

•   label=filetype:TYPE: Set the label file type for the pod files

•   label=disable: Turn off label separation for the pod

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

•   label=nested: Allows SELinux modifications within the container. Containers are allowed to modify SELinux labels on files and processes, as long as SELinux policy allows. Without nested, containers view SELinux as disabled, even when it is enabled on the host. Containers are prevented from setting any labels.

•   mask=/path/1:/path/2: The paths to mask separated by a colon. A masked path cannot be accessed inside the containers within the pod.

•   no-new-privileges: Disable container processes from gaining additional privileges through the execve(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. via setcap) are not added to the permitted capability set. For more details, see: https://docs.kernel.org/userspace-api/no_new_privs.html.

•   seccomp=unconfined: Turn off seccomp confinement for the pod.

•   seccomp=profile.json: JSON file to be used as a seccomp filter. Note that the io.podman.annotations.seccomp annotation is set with the specified value as shown in podman inspect.

•   proc-opts=OPTIONS : Comma-separated list of options to use for the /proc mount. More details for the possible mount options are specified in the proc(5) man page.

•   unmask=ALL or /path/1:/path/2, or shell expanded paths (/proc/*): Paths to unmask separated by a colon. If set to ALL, 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 setting label=false in the containers.conf(5) file.

  --share=namespace
A comma-separated list of kernel namespaces to share. If none or "" is specified, no namespaces are shared, and the infra container is not created unless explicitly specified via --infra=true. The namespaces to choose from are cgroup, ipc, net, pid, uts. If the option is prefixed with a "+", the namespace is appended to the default list. Otherwise, it replaces the default list. Defaults match Kubernetes default (ipc, net, uts)

  --share-parent
This boolean determines whether or not all containers entering the pod use the pod as their cgroup parent. The default value of this option is true. Use the --share option to share the cgroup namespace rather than a cgroup parent in a pod.

Note: This option conflicts with the --share=cgroup option since that option sets the pod as the cgroup parent but enters the container into the same cgroupNS as the infra container.

  --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 pod. 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.

  --subgidname=name
Run the container in a new user namespace using the map with name in the /etc/subgid file. When running rootless, the user needs the necessary permissions to use the mapping. See subgid(5). This flag conflicts with --userns and --gidmap. Together with --gidmap it acts as if --gidmap was passed with all mappings of the name group in /etc/subgid.

  --subuidname=name
Run the container in a new user namespace using the map with name in the /etc/subuid file. When running rootless, the user needs the necessary permissions to use the mapping. See subuid(5). This flag conflicts with --userns and --uidmap. Together with --uidmap it acts as if --uidmap was passed with all mappings of the name user in /etc/subuid.

  --sysctl=name=value
Configure namespaced kernel parameters for all containers in the pod.

For the IPC namespace, the following sysctls are allowed:

•   kernel.msgmax

•   kernel.msgmnb

•   kernel.msgmni

•   kernel.sem

•   kernel.shmall

•   kernel.shmmax

•   kernel.shmmni

•   kernel.shm_rmid_forced

•   Sysctls beginning with fs.mqueue.*

Note: if the ipc namespace is not shared within the pod, the above sysctls are not allowed.

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.

  --uidmap=container_uid:from_uid[:amount]
Run all containers in the pod in a new user namespace using the supplied 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.

  --userns=mode
Set the user namespace mode for all the containers in a pod. It defaults to the PODMAN_USERNS environment variable. An empty value ("") means user namespaces are disabled.

Rootless user --userns=Key mappings:
Key | Host User | Container User
"" | $UID | 0 (Default User account mapped to root user in container.)
host | $UID | 0 (Default User account mapped to root user in container.)
keep-id | $UID | $UID (Map user account to same UID within container.)
auto | $UID | nil (Host User UID is not mapped into container.)
nomap | $UID | nil (Host User UID is not mapped into container.)

Valid mode values are:

•   auto[:OPTIONS,...]: automatically create a namespace. It is possible to specify these options to auto:

    •   gidmapping=CONTAINER_GID:HOST_GID:SIZE to force a GID mapping to be present in the user namespace.

    •   size=SIZE: to specify an explicit size for the automatic user namespace. e.g. --userns=auto:size=8192. If size is not specified, auto estimates the size for the user namespace.

    •   uidmapping=CONTAINER_UID:HOST_UID:SIZE to force a UID mapping to be present in the user namespace.

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

•   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.

  --uts=mode
Set the UTS namespace mode for the pod. The following values are supported:

•   host: use the host's UTS namespace inside the pod.

•   private: create a new namespace for the pod (default).

•   ns:[path]: run the pod in the given existing UTS namespace.

  --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. 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.

(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|ro

•   z|Z

•   [O]

•   [U]

•   [no]copy

•   [no]dev

•   [no]exec

•   [no]suid

•   [r]bind

•   [r]shared|[r]slave|[r]private[r]unbindable [1] ⟨#Footnote1⟩

•   idmap[=options]

•   nocreate

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.

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 the volume. This is useful when you want to ensure that a volume was explicitly created before use.
    $ podman pod create -v myvolume:/data:nocreate alpine

Specify multiple -v options to mount one or more volumes into a pod.

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

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 occurs under the following conditions:

•   The volume was not used yet (has NeedsChown set to true)

•   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 is chowned to match the container's process user and group, mapped to the host user namespace if user namespace remapping is enabled.

If a pod 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 pod, 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 pod.

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 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.

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. Only the current pod can use a private volume.

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 :Z on 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 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 changed 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 pod. For example if a user wanted to volume mount their entire home directory into a pod, they need to disable SELinux separation.
    $ podman pod 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 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, 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 pod 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 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.

Do not modify the source directory mounted into the pod 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 pod 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 pod 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 pod, use the rbind option. By default the bind option is used, and submounts of the source directory is not mounted into the pod.

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 pod.

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.

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 pod 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 #.

  --volumes-from=CONTAINER[:OPTIONS]
Mount volumes from the specified container(s). Used to share volumes between containers and pods. The options is a comma-separated list with the following available elements:

•   rw|ro

•   z

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

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.

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.

EXAMPLES
Create a named pod.
    $ podman pod create --name test

Create a named pod.
    $ podman pod create mypod

Create a pod without an infra container.
    $ podman pod create --infra=false

Create a named pod with infra container command to run.
    $ podman pod create --infra-command /top toppod

Create a pod with published ports on the host.
    $ podman pod create --publish 8443:443

Create a pod with the specified network.
    $ podman pod create --network pasta

Create a pod on two networks.
    $ podman pod create --network net1:ip=10.89.1.5 --network net2:ip=10.89.10.10

Create a pod with shared CPU and memory limits for all containers.
    $ podman pod create --cpus=2 --memory=512m mypod

Create a pod with shared volume mounts accessible to all containers.
    $ podman pod create --volume /host/path:/container/path:Z mypod

Create a pod with shared resource limits and volume mounts for all containers.
    $ podman pod create --volume /data:/data:Z --volume /config:/etc/config:ro --cpus=1.5 --memory=1g --cpu-shares=512 mypod

Create a pod with shared device access and resource limits.
    $ podman pod create --device /dev/sda:/dev/sda:rw --cpus=4 --memory=2g --blkio-weight=500 mypod

Create a pod with shared CPU set limits and volumes from another container that will be shared to all containers in the pod.
    $ podman pod create --cpuset-cpus=0,2 --volumes-from=source-container --memory=1g mypod

Create a pod with shared resources and add containers to it.
    $ podman pod create --cpus=2 --memory=1g --volume /data:/data:Z mypod
    $ podman create --pod mypod nginx
    $ podman create --pod mypod redis

SEE ALSO
podman(1), podman-pod(1), podman-kube-play(1), containers.conf(1), cgroups(7)

  Troubleshooting
See podman-troubleshooting(7) for solutions to common issues.

HISTORY
July 2018, Originally compiled by Peter Hunt pehunt@redhat.com ⟨mailto:pehunt@redhat.com⟩

FOOTNOTES
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.