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% podman-volume-create 1

NAME

podman-volume-create - Create a new volume

SYNOPSIS

podman volume create [options] [name]

DESCRIPTION

Creates an empty volume and prepares it to be used by containers. The volume can be created with a specific name, if a name is not given a random name is generated. You can add metadata to the volume by using the --label flag and driver options can be set using the --opt flag.

OPTIONS

--driver, -d=driver

Specify the volume driver name (default local). There are two drivers supported by Podman itself: local and image.

The local driver uses a directory on disk as the backend by default, but can also use the mount(8) command to mount a filesystem as the volume if --opt is specified.

The image driver uses an image as the backing store of for the volume. An overlay filesystem is created, which allows changes to the volume to be committed as a new layer on top of the image.

Using a value other than local or image, Podman attempts to create the volume using a volume plugin with the given name. Such plugins must be defined in the volume_plugins section of the containers.conf(5) configuration file.

--help

Print usage statement

--ignore

Don't fail if the named volume already exists, instead just print the name. Note that the new options are not applied to the existing volume.

--label, -l=label

Set metadata for a volume (e.g., --label mykey=value).

--opt, -o=option

Set driver specific options. For the default driver, local, this allows a volume to be configured to mount a filesystem on the host.

For the local driver the following options are supported: type, device, o, and [no]copy.

  • The type option sets the type of the filesystem to be mounted, and is equivalent to the -t flag to mount(8).
  • The device option sets the device to be mounted, and is equivalent to the device argument to mount(8).
  • The copy option enables copying files from the container image path where the mount is created to the newly created volume on the first run. copy is the default.

The o option sets options for the mount, and is equivalent to the filesystem options (also -o) passed to mount(8) with the following exceptions:

  • The o option supports uid and gid options to set the UID and GID of the created volume that are not normally supported by mount(8).
  • The o option supports the size option to set the maximum size of the created volume, the inodes option to set the maximum number of inodes for the volume, and noquota to completely disable quota support even for tracking of disk usage. The size option is supported on the "tmpfs" and "xfs[note]" file systems. The inodes option is supported on the "xfs[note]" file systems. Note: xfs filesystems must be mounted with the prjquota flag described in the xfs_quota(8) man page. Podman will throw an error if they're not.
  • The o option supports using volume options other than the UID/GID options with the local driver and requires root privileges.
  • The o options supports the timeout option which allows users to set a driver specific timeout in seconds before volume creation fails. For example, --opt=o=timeout=10 sets a driver timeout of 10 seconds.

Note Do not confuse the --opt,-o create option with the -o mount option. For example, with podman volume create, use -o=o=uid=1000 not -o=uid=1000.

For the image driver, the only supported option is image, which specifies the image the volume is based on. This option is mandatory when using the image driver.

When not using the local and image drivers, the given options are passed directly to the volume plugin. In this case, supported options are dictated by the plugin in question, not Podman.

EXAMPLES

Create empty volume.

$ podman volume create

Create empty named volume.

$ podman volume create myvol

Create empty named volume with specified label.

$ podman volume create --label foo=bar myvol

Create tmpfs named volume with specified size and mount options.

# podman volume create --opt device=tmpfs --opt type=tmpfs --opt o=size=2M,nodev,noexec myvol

Create tmpfs named volume testvol with specified options.

# podman volume create --opt device=tmpfs --opt type=tmpfs --opt o=uid=1000,gid=1000 testvol

Create image named volume using the specified local image in containers/storage.

# podman volume create --driver image --opt image=fedora:latest fedoraVol

QUOTAS

podman volume create uses XFS project quota controls for controlling the size and the number of inodes of builtin volumes. The directory used to store the volumes must be an XFS file system and be mounted with the pquota option.

Example /etc/fstab entry:

/dev/podman/podman-var /var xfs defaults,x-systemd.device-timeout=0,pquota 1 2

Podman generates project IDs for each builtin volume, but these project IDs need to be unique for the XFS file system. These project IDs by default are generated randomly, with a potential for overlap with other quotas on the same file system.

The xfs_quota tool can be used to assign a project ID to the storage driver directory, e.g.:

echo 100000:/var/lib/containers/storage/overlay >> /etc/projects
echo 200000:/var/lib/containers/storage/volumes >> /etc/projects
echo storage:100000 >> /etc/projid
echo volumes:200000 >> /etc/projid
xfs_quota -x -c 'project -s storage volumes' /<xfs mount point>

In the example above we are configuring the overlay storage driver for newly created containers as well as volumes to use project IDs with a start offset. All containers are assigned larger project IDs (e.g. >= 100000). All volume assigned project IDs larger project IDs starting with 200000. This prevents xfs_quota management conflicts with containers/storage.

MOUNT EXAMPLES

podman volume create allows the type, device, and o options to be passed to mount(8) when using the local driver.

s3fs-fuse

s3fs-fuse or just s3fs, is a fuse filesystem that allows s3 prefixes to be mounted as filesystem mounts.

Installing:

$ doas dnf install s3fs-fuse

Simple usage:

$ s3fs --help
$ s3fs -o use_xattr,endpoint=aq-central-1 bucket:/prefix /mnt

Equivalent through mount(8)

$ mount -t fuse.s3fs -o use_xattr,endpoint=aq-central-1 bucket:/prefix /mnt

Equivalent through podman volume create

$ podman volume create s3fs-fuse-volume -o type=fuse.s3fs -o device=bucket:/prefix -o o=use_xattr,endpoint=aq-central-1

The volume can then be mounted in a container with

$ podman run -v s3fs-fuse-volume:/s3:z --rm -it fedora:latest

Please see the available options on their wiki.

Using with other container users

The above example works because the volume is mounted as the host user and inside the container root is mapped to the user in the host.

If the mount is accessed by a different user inside the container, a "Permission denied" error will be raised.

$ podman run --user bin:bin -v s3fs-fuse-volume:/s3:z,U --rm -it fedora:latest
$ ls /s3
# ls: /s3: Permission denied

In FUSE-land, mounts are protected for the user who mounted them; specify the allow_other mount option if other users need access.

Note: This will remove the normal fuse security measures on the mount point, after which, the normal filesystem permissions will have to protect it

$ podman volume create s3fs-fuse-other-volume -o type=fuse.s3fs -o device=bucket:/prefix -o o=allow_other,use_xattr,endpoint=aq-central-1
$ podman run --user bin:bin -v s3fs-fuse-volume:/s3:z,U --rm -it fedora:latest
$ ls /s3

The Prefix must exist

s3fs will fail to mount if the prefix does not exist in the bucket.

Create a s3-directory by putting an empty object at the desired prefix/ key

$ aws s3api put-object --bucket bucket --key prefix/

If performance is the priority, please check out the more performant goofys.

FUSE filesystems exist for Google Cloud Storage and Azure Blob Storage

SEE ALSO

podman(1), containers.conf(5), podman-volume(1), mount(8), xfs_quota(8), xfs_quota(8), projects(5), projid(5)

HISTORY

January 2020, updated with information on volume plugins by Matthew Heon mheon@redhat.com November 2018, Originally compiled by Urvashi Mohnani umohnani@redhat.com