STORAGE OPTIONS TABLE

The storage.options table supports the following options:

additionalimagestores=[]
Paths to additional container image stores. Usually these are read/only and stored on remote network shares.

pull_options = {enable_partial_images = "false", use_hard_links = "false", ostree_repos=""}

Allows specification of how storage is populated when pulling images. This option can speed the pulling process of images compressed with format zstd:chunked. Containers/storage looks for files within images that are being pulled from a container registry that were previously pulled to the host. It can copy or create a hard link to the existing file when it finds them, eliminating the need to pull them from the container registry. These options can deduplicate pulling of content, disk storage of content and can allow the kernel to use less memory when running containers.

containers/storage supports four keys
* enable_partial_images="true" | "false"
Tells containers/storage to look for files previously pulled in storage
rather then always pulling them from the container registry.
* use_hard_links = "false" | "true"
Tells containers/storage to use hard links rather then create new files in
the image, if an identical file already existed in storage.
* ostree_repos = ""
Tells containers/storage where an ostree repository exists that might have
previously pulled content which can be used when attempting to avoid
pulling content from the container registry

remap-uids="" remap-gids=""
Remap-UIDs/GIDs is the mapping from UIDs/GIDs as they should appear inside of a container, to the UIDs/GIDs outside of the container, and the length of the range of UIDs/GIDs. Additional mapped sets can be listed and will be heeded by libraries, but there are limits to the number of mappings which the kernel will allow when you later attempt to run a container.

Example
remap-uids = 0:1668442479:65536
remap-gids = 0:1668442479:65536

These mappings tell the container engines to map UID 0 inside of the container to UID 1668442479 outside. UID 1 will be mapped to 1668442480. UID 2 will be mapped to 1668442481, etc, for the next 65533 UIDs in succession.

remap-user="" remap-group=""
Remap-User/Group is a user name which can be used to look up one or more UID/GID ranges in the /etc/subuid or /etc/subgid file. Mappings are set up starting with an in-container ID of 0 and then a host-level ID taken from the lowest range that matches the specified name, and using the length of that range. Additional ranges are then assigned, using the ranges which specify the lowest host-level IDs first, to the lowest not-yet-mapped in-container ID, until all of the entries have been used for maps.

Example
remap-user = "containers"
remap-group = "containers"

root-auto-userns-user=""
Root-auto-userns-user is a user name which can be used to look up one or more UID/GID ranges in the /etc/subuid and /etc/subgid file. These ranges will be partitioned to containers configured to create automatically a user namespace. Containers configured to automatically create a user namespace can still overlap with containers having an explicit mapping set. This setting is ignored when running as rootless.

auto-userns-min-size=1024
Auto-userns-min-size is the minimum size for a user namespace created automatically.

auto-userns-max-size=65536
Auto-userns-max-size is the maximum size for a user namespace created automatically.

disable-volatile=true
If disable-volatile is set, then the "volatile" mount optimization is disabled for all the containers.

STORAGE OPTIONS FOR AUFS TABLE

The storage.options.aufs table supports the following options:

mountopt=""
Comma separated list of default options to be used to mount container images. Suggested value "nodev". Mount options are documented in the mount(8) man page.

STORAGE OPTIONS FOR BTRFS TABLE

The storage.options.btrfs table supports the following options:

min_space=""
Specifies the min space in a btrfs volume.

size=""
Maximum size of a container image. This flag can be used to set quota on the size of container images. (format: [], where unit = b (bytes), k (kilobytes), m (megabytes), or g (gigabytes))

STORAGE OPTIONS FOR THINPOOL (devicemapper) TABLE

The storage.options.thinpool table supports the following options for the devicemapper driver:

autoextend_percent=""
Tells the thinpool driver the amount by which the thinpool needs to be grown. This is specified in terms of % of pool size. So a value of 20 means that when threshold is hit, pool will be grown by 20% of existing pool size. (default: 20%)

autoextend_threshold=""
Tells the driver the thinpool extension threshold in terms of percentage of pool size. For example, if threshold is 60, that means when pool is 60% full, threshold has been hit. (default: 80%)

basesize=""
Specifies the size to use when creating the base device, which limits the size of images and containers. (default: 10g)

blocksize=""
Specifies a custom blocksize to use for the thin pool. (default: 64k)

directlvm_device=""
Specifies a custom block storage device to use for the thin pool. Required for using graphdriver devicemapper.

directlvm_device_force=""
Tells driver to wipe device (directlvm_device) even if device already has a filesystem. (default: false)

fs="xfs"
Specifies the filesystem type to use for the base device. (default: xfs)

log_level=""
Sets the log level of devicemapper.

0: LogLevelSuppress 0 (default)
2: LogLevelFatal
3: LogLevelErr
4: LogLevelWarn
5: LogLevelNotice
6: LogLevelInfo
7: LogLevelDebug

metadata_size=""
metadata_size is used to set the pvcreate --metadatasize options when creating thin devices. (Default 128k)

min_free_space=""
Specifies the min free space percent in a thin pool required for new device creation to succeed. Valid values are from 0% - 99%. Value 0% disables. (default: 10%)

mkfsarg=""
Specifies extra mkfs arguments to be used when creating the base device.

mountopt=""
Comma separated list of default options to be used to mount container images. Suggested value "nodev". Mount options are documented in the mount(8) man page.

size=""
Maximum size of a container image. This flag can be used to set quota on the size of container images. (format: [], where unit = b (bytes), k (kilobytes), m (megabytes), or g (gigabytes))

use_deferred_deletion=""
Marks thinpool device for deferred deletion. If the thinpool is in use when the driver attempts to delete it, the driver will attempt to delete device every 30 seconds until successful, or when it restarts. Deferred deletion permanently deletes the device and all data stored in the device will be lost. (default: true).

use_deferred_removal=""
Marks devicemapper block device for deferred removal. If the device is in use when its driver attempts to remove it, the driver tells the kernel to remove the device as soon as possible. Note this does not free up the disk space, use deferred deletion to fully remove the thinpool. (default: true).

xfs_nospace_max_retries=""
Specifies the maximum number of retries XFS should attempt to complete IO when ENOSPC (no space) error is returned by underlying storage device. (default: 0, which means to try continuously.)

STORAGE OPTIONS FOR OVERLAY TABLE

The storage.options.overlay table supports the following options:

ignore_chown_errors = "false"
ignore_chown_errors can be set to allow a non privileged user running with a single UID within a user namespace to run containers. The user can pull and use any image even those with multiple uids. Note multiple UIDs will be squashed down to the default uid in the container. These images will have no separation between the users in the container. (default: false)

inodes=""
Maximum inodes in a read/write layer. This flag can be used to set a quota on the inodes allocated for a read/write layer of a container.

force_mask = "0000|shared|private"
ForceMask specifies the permissions mask that is used for new files and directories. The values "shared" and "private" are accepted. (default: ""). Octal permission masks are also accepted.

OCTAL: Users can experiment with other OCTAL Permissions.

Note: The force_mask Flag is an experimental feature, it could change in the future. When "force_mask" is set the original permission mask is stored in the "user.containers.override_stat" xattr and the "mount_program" option must be specified. Mount programs like "/usr/bin/fuse-overlayfs" present the extended attribute permissions to processes within containers rather than the "force_mask" permissions.

mount_program=""
Specifies the path to a custom program to use instead of using kernel defaults for mounting the file system. In rootless mode, without the CAP_SYS_ADMIN capability, many kernels prevent mounting of overlay file systems, requiring you to specify a mount_program. The mount_program option is also required on systems where the underlying storage is btrfs, aufs, zfs, overlay, or ecryptfs based file systems.
mount_program = "/usr/bin/fuse-overlayfs"

mountopt=""
Comma separated list of default options to be used to mount container images. Suggested value "nodev". Mount options are documented in the mount(8) man page.

skip_mount_home=""
Tell storage drivers to not create a PRIVATE bind mount on their home directory.

size=""
Maximum size of a read/write layer. This flag can be used to set quota on the size of a read/write layer of a container. (format: [], where unit = b (bytes), k (kilobytes), m (megabytes), or g (gigabytes))

STORAGE OPTIONS FOR VFS TABLE

The storage.options.vfs table supports the following options:

ignore_chown_errors = "false"
ignore_chown_errors can be set to allow a non privileged user running with a single UID within a user namespace to run containers. The user can pull and use any image even those with multiple uids. Note multiple UIDs will be squashed down to the default uid in the container. These images will have no separation between the users in the container. (default: false)

STORAGE OPTIONS FOR ZFS TABLE

The storage.options.zfs table supports the following options:

fsname=""
File System name for the zfs driver

mountopt=""
Comma separated list of default options to be used to mount container images. Suggested value "nodev". Mount options are documented in the mount(8) man page.

size=""
Maximum size of a container image. This flag can be used to set quota on the size of container images. (format: [], where unit = b (bytes), k (kilobytes), m (megabytes), or g (gigabytes))