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:
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".
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. `$HOME/containers/storage`)
A common use case for this field is to provide a local storage directory when user home directories are NFS-mounted (podman does not support container storage over NFS).
The image storage path (the default is assumed to be the same as `graphroot`). Path of the imagestore, which is different from `graphroot`. By default, images in the storage library are stored in the `graphroot`. If `imagestore` is provided, newly pulled images will be stored in the `imagestore` location. All other storage continues to be stored in the `graphroot`. When using the `overlay` driver, images previously stored in the `graphroot` remain accessible. Internally, the storage library mounts `graphroot` as an `additionalImageStore` to allow this behavior.
A common use case for the `imagestore` field is users who need to split filesystems in different partitions. The `imagestore` partition stores images and the `graphroot` partition stores container content created from the images.
Imagestore, if set, must be different from `graphroot`.
Default directory to store all temporary writable content created by container storage programs. The rootless runroot path supports environment variable substitutions (ie. `$HOME/containers/storage`)
**driver_priority**=[]
Priority list for the storage drivers that will be tested one after the other to pick the storage driver if it is not defined. The first storage driver in this list that can be used, will be picked as the new one and all subsequent ones will not be tried. If all drivers in this list are not viable, then **all** known drivers will be tried and the first working one will be picked.
By default, the storage driver is set via the `driver` option. If it is not defined, then the best driver will be picked according to the current platform. This option allows you to override this internal priority list with a custom one to prefer certain drivers.
Setting this option only has an effect if the local storage has not been initialized yet and the driver name is not set.
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.
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/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. This setting overrides the Remap-UIDs/GIDs setting.
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: <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
**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: <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)
**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
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.
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: <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
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.
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.
