Provided by: containers-storage_1.15.8+dfsg1-1ubuntu2.1_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=""
container storage driver (default: "overlay")
Default 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.
graphroot=""
container storage graph dir (default: "/var/lib/containers/storage")
Default directory to store all writable content created by container storage programs.
runroot=""
container storage run dir (default: "/var/run/containers/storage")
Default directory to store all temporary writable content created by container storage
programs.
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.
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 = "storage"
remap-group = "storage"
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: <number>[<unit>], 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
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: <number>[<unit>], 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)
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.
size=""
Maximum size of a container image. This flag can be used to set quota on the size of
container images. (format: <number>[<unit>], 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: <number>[<unit>], 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
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.
SEE ALSO
semanage(8), restorecon(8), mount(8)
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. The storage.conf file for
rootless users is stored in the $HOME/.config/containers/storage.conf file.
HISTORY
May 2017, Originally compiled by Dan Walsh ⟨dwalsh@redhat.com⟩ Format copied from
crio.conf man page created by Aleksa Sarai ⟨asarai@suse.de⟩