Provided by: containers-storage_1.43.0+ds1-8ubuntu0.1_amd64 
NAME
storage.conf - Syntax of Container Storage configuration file
DESCRIPTION
The STORAGE configuration file specifies all of the available container storage options
for tools using shared container storage, but in a TOML format that can be more easily
modified and versioned.
FORMAT
The [TOML format][toml] is used as the encoding of the configuration file. Every option
and subtable listed here is nested under a global "storage" table. No bare options are
used. The format of TOML can be simplified to:
[table]
option = value
[table.subtable1]
option = value
[table.subtable2]
option = value
STORAGE TABLE
The storage table supports the following options:
driver=""
Copy On Write (COW) container storage driver. Valid drivers are "overlay", "vfs",
"devmapper", "aufs", "btrfs", and "zfs". Some drivers (for example, "zfs", "btrfs", and
"aufs") may not work if your kernel lacks support for the filesystem. This field is
required to guarantee proper operation. Valid rootless drivers are "btrfs", "overlay",
and "vfs". Rootless users default to the driver defined in the system configuration when
possible. When the system configuration uses an unsupported rootless driver, rootless
users default to "overlay" if available, otherwise "vfs".
graphroot=""
container storage graph dir (default: "/var/lib/containers/storage") Default directory
to store all writable content created by container storage programs. The rootless
graphroot path supports environment variable substitutions (ie. $HOME/containers/storage).
When changing the graphroot location on an SELINUX system, ensure the labeling matches the
default locations labels with the following commands:
# semanage fcontext -a -e /var/lib/containers/storage /NEWSTORAGEPATH
# restorecon -R -v /NEWSTORAGEPATH
In rootless mode you would set
# semanage fcontext -a -e $HOME/.local/share/containers NEWSTORAGEPATH
$ restorecon -R -v /NEWSTORAGEPATH
rootless_storage_path="$HOME/.local/share/containers/storage"
Storage path for rootless users. By default the graphroot for rootless users is set to
$XDG_DATA_HOME/containers/storage, if XDG_DATA_HOME is set. Otherwise
$HOME/.local/share/containers/storage is used. This field can be used if administrators
need to change the storage location for all users. The rootless storage path supports
environment variable substitutions (ie. $HOME/containers/storage)
A common use case for this field is to provide a local storage directory when user home
directories are NFS-mounted (podman does not support container storage over NFS).
runroot=""
container storage run dir (default: "/run/containers/storage") Default directory to
store all temporary writable content created by container storage programs. The rootless
runroot path supports environment variable substitutions (ie. $HOME/containers/storage)
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.
• ``: Not set All files/directories, get set with the permissions identified within
the image.
• private: it is equivalent to 0700. All files/directories get set with 0700
permissions. The owner has rwx access to the files. No other users on the system
can access the files. This setting could be used with networked based home
directories.
• shared: it is equivalent to 0755. The owner has rwx access to the files and
everyone else can read, access and execute them. This setting is useful for
sharing containers storage with other users. For instance, a storage owned by
root could be shared to rootless users as an additional store. NOTE: All files
within the image are made readable and executable by any user on the system. Even
/etc/shadow within your image is now readable by any user.
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))
SELINUX LABELING
When running on an SELinux system, if you move the containers storage graphroot directory,
you must make sure the labeling is correct.
Tell SELinux about the new containers storage by setting up an equivalence record. This
tells SELinux to label content under the new path, as if it was stored under
/var/lib/containers/storage.
semanage fcontext -a -e /var/lib/containers NEWSTORAGEPATH
restorecon -R -v NEWSTORAGEPATH
In rootless mode, you would set
semanage fcontext -a -e $HOME/.local/share/containers NEWSTORAGEPATH
restorecon -R -v NEWSTORAGEPATH
The semanage command above tells SELinux to setup the default labeling of NEWSTORAGEPATH
to match /var/lib/containers. The restorecon command tells SELinux to apply the labels to
the actual content.
Now all new content created in these directories will automatically be created with the
correct label.
QUOTAS
Container storage implements XFS project quota controls for overlay storage containers and
volumes. The directory used to store the containers 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
Container storage generates project ids for each container and builtin volume, but these
project ids need to be unique for the XFS 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, the storage directory project id will be used as a "start offset"
and all containers will be assigned larger project ids (e.g. >= 100000). Then the volumes
directory project id will be used as a "start offset" and all volumes will be assigned
larger project ids (e.g. >= 200000). This is a way to prevent xfs_quota management from
conflicting with containers/storage.
FILES
Distributions often provide a /usr/share/containers/storage.conf file to define default
storage configuration. Administrators can override this file by creating
/etc/containers/storage.conf to specify their own configuration. Likewise rootless users
can create a storage.conf file to override the system storage.conf files. Files should be
stored in the $XDG_CONFIG_HOME/containers/storage.conf file. If $XDG_CONFIG_HOME is not
set then the file $HOME/.config/containers/storage.conf is used.
Note: The storage.conf file overrides all other strorage.conf files. Container engines run
by users with a storage.conf file in their home directory do not use options in the system
storage.conf files.
/etc/projects - XFS persistent project root definition /etc/projid - XFS project name
mapping file
SEE ALSO
semanage(8), restorecon(8), mount(8), fuse-overlayfs(1), xfs_quota(8), projects(5),
projid(5)
HISTORY
May 2017, Originally compiled by Dan Walsh dwalsh@redhat.com ⟨mailto:dwalsh@redhat.com⟩
Format copied from crio.conf man page created by Aleksa Sarai asarai@suse.de
⟨mailto:asarai@suse.de⟩