@ -9,7 +9,7 @@ Containerfile(Dockerfile) - automate the steps of creating a container image
The **Containerfile** is a configuration file that automates the steps of creating a container image. It is similar to a Makefile. Container engines (Podman, Buildah, Docker) read instructions from the **Containerfile** to automate the steps otherwise performed manually to create an image. To build an image, create a file called **Containerfile**.
The **Containerfile** describes the steps taken to assemble the image. When the
**Containerfile** has been created, call the `buildah bud`, `podman build`, `docker build` command,
**Containerfile** has been created, call the `buildah build`, `podman build`, `docker build` command,
using the path of context directory that contains **Containerfile** as the argument. Podman and Buildah default to **Containerfile** and will fall back to **Dockerfile**. Docker only will search for **Dockerfile** in the context directory.
@ -31,7 +31,7 @@ A Containerfile is similar to a Makefile.
# USAGE
```
buildah bud .
buildah build .
podman build .
```
@ -40,7 +40,7 @@ A Containerfile is similar to a Makefile.
build.
```
buildah bud -t repository/tag .
buildah build -t repository/tag .
podman build -t repository/tag .
```
@ -49,19 +49,19 @@ A Containerfile is similar to a Makefile.
to a new image if necessary, before finally outputting the ID of the new
image.
Container engines re-use intermediate images whenever possible. This significantly
Container engines reuse intermediate images whenever possible. This significantly
accelerates the *build* process.
# FORMAT
`FROM image`
`FROM image [AS <name>]`
`FROM image:tag`
`FROM image:tag [AS <name>]`
`FROM image@digest`
`FROM image@digest [AS <name>]`
-- The **FROM** instruction sets the base image for subsequent instructions. A
valid Containerfile must have either **ARG** or *FROM** as its first instruction.
valid Containerfile must have either **ARG** or **FROM** as its first instruction.
If **FROM** is not the first instruction in the file, it may only be preceded by
one or more ARG instructions, which declare arguments that are used in the next FROM line in the Containerfile.
The image can be any valid image. It is easy to start by pulling an image from the public
@ -82,6 +82,9 @@ A Containerfile is similar to a Makefile.
-- If no digest is given to the **FROM** instruction, container engines apply the
`latest` tag. If the used tag does not exist, an error is returned.
-- A name can be assigned to a build stage by adding **AS name** to the instruction.
The name can be referenced later in the Containerfile using the **FROM** or **COPY --from=<name>** instructions.
**MAINTAINER**
-- **MAINTAINER** sets the Author field for the generated images.
Useful for providing users with an email or url for support.
@ -106,7 +109,7 @@ Current supported mount TYPES are bind, cache, secret and tmpfs.
@ -114,45 +117,57 @@ Current supported mount TYPES are bind, cache, secret and tmpfs.
Common Options:
· src, source: mount source spec for bind and volume. Mandatory for bind. If `from` is specified, `src` is the subpath in the `from` field.
· src, source: mount source spec for bind and volume. Mandatory for bind. If `from` is specified, `src` is the subpath in the `from` field.
· dst, destination, target: mount destination spec.
· dst, destination, target: mount destination spec.
· ro, read-only: true (default) or false.
· ro, read-only: true (default) or false.
Options specific to bind:
· bind-propagation: shared, slave, private, rshared, rslave, or rprivate(default). See also mount(2).
· bind-propagation: shared, slave, private, rshared, rslave, or rprivate(default). See also mount(2).
. bind-nonrecursive: do not setup a recursive bind mount. By default it is recursive.
· from: stage or image name for the root of the source. Defaults to the build context.
· relabel=shared, z: Relabels src content with a shared label.
. relabel=private, Z: Relabels src content with a private label.
Labeling systems like SELinux require proper labels on the bind mounted content mounted into a container. Without a label, the security system might prevent the processes running in side the container from using the content. By default, container engines do not change the labels set by the OS. The relabel flag tells the engine to relabel file objects on the shared mountz.
The relabel=shared and z options tell the engine that two or more containers will share the mount content. The engine labels the content with a shared content label.
. bind-nonrecursive: do not setup a recursive bind mount. By default it is recursive.
The relabel=private and Z options tell the engine to label the content with a private unshared label. Only the current container can use a private mount.
· from: stage or image name for the root of the source. Defaults to the build context.
Relabeling walks the file system under the mount and changes the label on each file, if the mount has thousands of inodes, this process takes a long time, delaying the start of the container.
· rw, read-write: allows writes on the mount.
· rw, read-write: allows writes on the mount.
Options specific to tmpfs:
· tmpfs-size: Size of the tmpfs mount in bytes. Unlimited by default in Linux.
· tmpfs-size: Size of the tmpfs mount in bytes. Unlimited by default in Linux.
· tmpfs-mode: File mode of the tmpfs in octal. (e.g. 700 or 0700.) Defaults to 1777 in Linux.
· tmpfs-mode: File mode of the tmpfs in octal. (e.g. 700 or 0700.) Defaults to 1777 in Linux.
· tmpcopyup: Path that is shadowed by the tmpfs mount is recursively copied up to the tmpfs itself.
· tmpcopyup: Path that is shadowed by the tmpfs mount is recursively copied up to the tmpfs itself.
Options specific to cache:
· id: Create a separate cache directory for a particular id.
· id: Create a separate cache directory for a particular id.
· mode: File mode for new cache directory in octal. Default 0755.
· mode: File mode for new cache directory in octal. Default 0755.
· ro, readonly: read only cache if set.
· ro, readonly: read only cache if set.
· uid: uid for cache directory.
· uid: uid for cache directory.
· gid: gid for cache directory.
· gid: gid for cache directory.
· from: stage name for the root of the source. Defaults to host cache directory.
· from: stage name for the root of the source. Defaults to host cache directory.
· rw, read-write: allows writes on the mount.
· rw, read-write: allows writes on the mount.
**RUN --network**
@ -204,7 +219,7 @@ Container engines pass secret the secret file into the build using the `--secret
- `id` is the identifier for the secret passed into the `buildah bud --secret` or `podman build --secret`. This identifier is associated with the RUN --mount identifier to use in the Containerfile.
- `id` is the identifier for the secret passed into the `buildah build --secret` or `podman build --secret`. This identifier is associated with the RUN --mount identifier to use in the Containerfile.
- `dst`|`target`|`destination` rename the secret file to a specific file in the Containerfile RUN command to use.
@ -221,7 +236,7 @@ RUN --mount=type=secret,id=mysecret,dst=/foobar cat /foobar
The secret needs to be passed to the build using the --secret flag. The final image built does not container the secret file:
@ -5,30 +5,33 @@ containers-auth.json - syntax for the registry authentication file
# DESCRIPTION
A credentials file in JSON format used to authenticate against container image registries.
A file in JSON format controlling authentication against container image registries.
The primary (read/write) file is stored at `${XDG_RUNTIME_DIR}/containers/auth.json` on Linux;
on Windows and macOS, at `$HOME/.config/containers/auth.json`.
When searching for the credential for a registry, the following files will be read in sequence until the valid credential is found:
first reading the primary (read/write) file, or the explicit override using an option of the calling application.
If credentials are not present, search in `${XDG_CONFIG_HOME}/containers/auth.json` (usually `~/.config/containers/auth.json`), `$HOME/.docker/config.json`, `$HOME/.dockercfg`.
If credentials are not present there,
the search continues in `${XDG_CONFIG_HOME}/containers/auth.json` (usually `~/.config/containers/auth.json`), `$HOME/.docker/config.json`, `$HOME/.dockercfg`.
Except the primary (read/write) file, other files are read-only, unless the user use an option of the calling application explicitly points at it as an override.
Except for the primary (read/write) file, other files are read-only unless the user, using an option of the calling application, explicitly points at it as an override.
## FORMAT
The auth.json file stores encrypted authentication information for the
user to container image registries. The file can have zero to many entries and
is created by a `login` command from a container tool such as `podman login`,
`buildah login` or `skopeo login`. Each entry either contains a single
hostname (e.g. `docker.io`) or a namespace (e.g. `quay.io/user/image`) as a key
and an auth token in the form of a base64 encoded string as value of `auth`. The
token is built from the concatenation of the username, a colon, and the
password. The registry name can additionally contain a repository name (an image
name without tag or digest) and namespaces. The path (or namespace) is matched
in its hierarchical order when checking for available authentications. For
example, an image pull for `my-registry.local/namespace/user/image:latest` will
The auth.json file stores, or references, credentials that allow the user to authenticate
to container image registries.
It is primarily managed by a `login` command from a container tool such as `podman login`,
`buildah login`, or `skopeo login`.
Each entry contains a single hostname (e.g., `docker.io`) or a namespace (e.g., `quay.io/user/image`) as a key,
and credentials in the form of a base64-encoded string as value of `auth`. The
base64-encoded string contains a concatenation of the username, a colon, and the
password.
When checking for available credentials, the relevant repository is matched
against available keys in its hierarchical order, going from most-specific to least-specific.
For example, an image pull for `my-registry.local/namespace/user/image:latest` will
result in a lookup in `auth.json` in the following order:
- `my-registry.local/namespace/user/image`
@ -77,10 +80,8 @@ preserving a fallback for `my-registry.local`:
An entry can be removed by using a `logout` command from a container
tool such as `podman logout` or `buildah logout`.
In addition, credential helpers can be configured for specific registries and the credentials-helper
software can be used to manage the credentials in a more secure way than depending on the base64 encoded authentication
provided by `login`. If the credential helpers are configured for specific registries, the base64 encoded authentication will not be used
for operations concerning credentials of the specified registries.
In addition, credential helpers can be configured for specific registries, and the credentials-helper
software can be used to manage the credentials more securely than storing only base64-encoded credentials in `auth.json`.
When the credential helper is in use on a Linux platform, the auth.json file would contain keys that specify the registry domain, and values that specify the suffix of the program to use (i.e. everything after docker-credential-). For example:
@ -61,18 +61,41 @@ The global `default` set of policy requirements is mandatory; all of the other f
<!-- NOTE: Keep this in sync with transports/transports.go! -->
## Supported transports and their scopes
See containers-transports(5) for general documentation about the transports and their reference syntax.
### `atomic:`
The `atomic:` transport refers to images in an Atomic Registry.
The deprecated `atomic:` transport refers to images in an Atomic Registry.
Supported scopes use the form _hostname_[`:`_port_][`/`_namespace_[`/`_imagestream_ [`:`_tag_]]],
i.e. either specifying a complete name of a tagged image, or prefix denoting
a host/namespace/image stream or a wildcarded expression for matching all
a host/namespace/image stream, or a wildcarded expression starting with `*.` for matching all
subdomains. For wildcarded subdomain matching, `*.example.com` is a valid case, but `example*.*.com` is not.
*Note:* The _hostname_ and _port_ refer to the container registry host and port (the one used
e.g. for `docker pull`), _not_ to the OpenShift API host and port.
### `containers-storage:`
Supported scopes have the form `[`_storage-specifier_`]`_image-scope_.
`[`_storage-specifier_`]` is usually `[`_graph-driver-name_`@`_graph-root_`]`, e.g. `[overlay@/var/lib/containers/storage]`.
_image-scope_ matching the individual image is
- a named Docker reference *in the fully expanded form*, either using a tag or digest. For example, `docker.io/library/busybox:latest` (*not* `busybox:latest`)
- and/or (depending on which one the user’s input provides) `@`_image-id_
More general scopes are prefixes of individual-image scopes, and specify a less-precisely-specified image, or a repository
(by omitting first the image ID, if any; then the digest, if any; and finally a tag, if any),
a repository namespace, or a registry host (by only specifying the host name and possibly a port number).
Finally, two full-store specifiers matching all images in the store are valid scopes:
- `[`_graph-driver-name_`@`_graph-root_`]` and
- `[`_graph-root_`]`
Note that some tools like Podman and Buildah hard-code overrides of the signature verification policy for “push” operations,
allowing these operations regardless of configuration in `policy.json`.
### `dir:`
The `dir:` transport refers to images stored in local directories.
@ -80,10 +103,10 @@ The `dir:` transport refers to images stored in local directories.
Supported scopes are paths of directories (either containing a single image or
subdirectories possibly containing images).
*Note:* The paths must be absolute and contain no symlinks. Paths violating these requirements may be silently ignored.
The top-level scope `"/"` is forbidden; use the transport default scope `""`,
for consistency with other transports.
*Note:*
- The paths must be absolute and contain no symlinks. Paths violating these requirements may be silently ignored.
- The top-level scope `"/"` is forbidden; use the transport default scope `""`,
for consistency with other transports.
### `docker:`
@ -93,24 +116,73 @@ Scopes matching individual images are named Docker references *in the fully expa
using a tag or digest. For example, `docker.io/library/busybox:latest` (*not* `busybox:latest`).
More general scopes are prefixes of individual-image scopes, and specify a repository (by omitting the tag or digest),
a repository namespace, or a registry host (by only specifying the host name)
or a wildcarded expression for matching all subdomains. For wildcarded subdomain
a repository namespace, or a registry host (by only specifying the host name and possibly a port number)
or a wildcarded expression starting with `*.`, for matching all subdomains (not including a port number). For wildcarded subdomain
matching, `*.example.com` is a valid case, but `example*.*.com` is not.
### `docker-archive:`
Only the default `""` scope is supported.
### `docker-daemon:`
For references using the _algo:digest_ format (referring to an image ID), only the default `""` scope is used.
For images using a named reference, scopes matching individual images are *in the fully expanded form*, either
using a tag or digest. For example, `docker.io/library/busybox:latest` (*not* `busybox:latest`).
More general named scopes are prefixes of individual-image scopes, and specify a repository (by omitting the tag or digest),
a repository namespace, or a registry host (by only specifying the host name and possibly a port number)
or a wildcarded expression starting with `*.`, for matching all subdomains (not including a port number). For wildcarded subdomain
matching, `*.example.com` is a valid case, but `example*.*.com` is not.
### `oci:`
The `oci:` transport refers to images in directories compliant with "Open Container Image Layout Specification".
Supported scopes use the form _directory_`:`_tag_, and _directory_ referring to
a directory containing one or more tags, or any of the parent directories.
Supported scopes are paths to directories
(either containing an OCI layout, or subdirectories possibly containing OCI layout directories).
The _reference_ annotation value, if any, is not used.
*Note:* See `dir:` above for semantics and restrictions on the directory paths, they apply to `oci:` equivalently.
*Note:*
- The paths must be absolute and contain no symlinks. Paths violating these requirements may be silently ignored.
- The top-level scope `"/"` is forbidden; use the transport default scope `""`,
for consistency with other transports.
### `tarball:`
### `oci-archive:`
Supported scopes are paths to OCI archives, and their parent directories
(either containing a single archive, or subdirectories possibly containing archives).
The _reference_ annotation value, if any, is not used.
*Note:*
- The paths must be absolute and contain no symlinks. Paths violating these requirements may be silently ignored.
- The top-level scope `"/"` is forbidden; use the transport default scope `""`,
for consistency with other transports.
### `ostree`:
Supported scopes have the form _repo-path_`:`_image-scope_; _repo_path_ is the path to the OSTree repository.
The `tarball:` transport refers to tarred up container root filesystems.
_image-scope_ is the _docker_reference_ part of the reference, with with a `:latest` tag implied if no tag is present,
and parent namespaces of the _docker_reference_ value (by omitting the tag, or a prefix specifying a higher-level namespace).
Scopes are ignored.
*Note:*
- The _repo_path_ must be absolute and contain no symlinks. Paths violating these requirements may be silently ignored.
### `sif:`
Supported scopes are paths to Singularity images, and their parent directories
(either containing images, or subdirectories possibly containing images).
*Note:*
- The paths must be absolute and contain no symlinks. Paths violating these requirements may be silently ignored.
- The top-level scope `"/"` is forbidden; use the transport default scope `""`,
for consistency with other transports.
### `tarball:`
The `tarball:` transport is an implementation detail of some import workflows. Only the default `""` scope is supported.
## Policy Requirements
@ -248,7 +320,9 @@ This requirement requires an image to be signed using a sigstore signature with
Exactly one of `keyPath`, `keyData` and `fulcio` must be present.
Exactly one of `keyPath`, `keyPaths`, `keyData`, `keyDatas` and `fulcio` must be present.
If `keyPath` or `keyData` is present, it contains a sigstore public key.
Only signatures made by this key are accepted.
If `keyPaths` or `keyDatas` is present, it contains sigstore public keys.
Only signatures made by any key in the list are accepted.
If `fulcio` is present, the signature must be based on a Fulcio-issued certificate.
One of `caPath` and `caData` must be specified, containing the public key of the Fulcio instance.
Both `oidcIssuer` and `subjectEmail` are mandatory,
exactly specifying the expected identity provider,
and the identity of the user obtaining the Fulcio certificate.
At most one of `rekorPublicKeyPath` and `rekorPublicKeyData` can be present;
At most one of `rekorPublicKeyPath`, `rekorPublicKeyPaths`, `rekorPublicKeyData` and `rekorPublicKeyDatas` can be present;
it is mandatory if `fulcio` is specified.
If a Rekor public key is specified,
the signature must have been uploaded to a Rekor server
and the signature must contain an (offline-verifiable) “signed entry timestamp”
proving the existence of the Rekor log record,
signed by the provided public key.
signed by one of the provided public keys.
The `signedIdentity` field has the same semantics as in the `signedBy` requirement described above.
Note that `cosign`-created signatures only contain a repository, so only `matchRepository` and `exactRepository` can be used to accept them (and that does not protect against substitution of a signed image with an unexpected tag).
To use this with images hosted on image registries, the relevant registry or repository must have the `use-sigstore-attachments` option enabled in containers-registries.d(5).
To use this with images hosted on image registries, the `use-sigstore-attachments` option needs to be enabled for the relevant registry or repository in the client's containers-registries.d(5).
@ -19,6 +19,12 @@ Container engines will use the `$HOME/.config/containers/registries.conf` if it
`credential-helpers`
: An array of default credential helpers used as external credential stores. Note that "containers-auth.json" is a reserved value to use auth files as specified in containers-auth.json(5). The credential helpers are set to `["containers-auth.json"]` if none are specified.
`additional-layer-store-auth-helper`
: A string containing the helper binary name. This enables passing registry credentials to an
Additional Layer Store every time an image is read using the `docker://`
transport so that it can access private registries. See the 'Enabling Additional Layer Store to access to private registries' section below for
more details.
### NAMESPACED `[[registry]]` SETTINGS
The bulk of the configuration is represented as an array of `[[registry]]`
@ -73,16 +79,16 @@ internet without having to change `Dockerfile`s, or to add redundancy).
: Accepts the same format as the `prefix` field, and specifies the physical location
of the `prefix`-rooted namespace.
By default, this equal to `prefix` (in which case `prefix` can be omitted and the
By default, this is equal to `prefix` (in which case `prefix` can be omitted and the
`[[registry]]` TOML table can only specify `location`).
Note that a mirror is associated only with the current `[[registry]]` TOML table. If using the example above, pulling the image `registry.com/image:latest` will hence only reach out to `mirror.registry.com`, and the mirrors associated with `example.com/foo` will not be considered.
### Enabling Additional Layer Store to access to private registries
The `additional-layer-store-auth-helper` option enables passing registry
credentials to an Additional Layer Store so that it can access private registries.
When accessing a private registry via an Additional Layer Store, a helper binary needs to be provided. This helper binary is
registered via the `additional-layer-store-auth-helper` option. Every time an image
is read using the `docker://` transport, the specified helper binary is executed
and receives registry credentials from stdin in the following format.
```json
{
"$image_reference": {
"username": "$username",
"password": "$password",
"identityToken": "$identityToken"
}
}
```
The format of `$image_reference` is `$repo{:$tag|@$digest}`.
Additional Layer Stores can use this helper binary to access the private registry.
## VERSION 1 FORMAT - DEPRECATED
VERSION 1 format is still supported but it does not support
using registry mirrors, longest-prefix matches, or location rewriting.
@ -27,7 +27,7 @@ No bare options are used. The format of TOML can be simplified to:
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.
Copy On Write (COW) container storage driver. Valid drivers are "overlay", "vfs", "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.
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).
**imagestore**=""
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`.
**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`)
@ -64,6 +71,12 @@ Default directory to store all temporary writable content created by container s
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.
**transient_store** = "false" | "true"
Transient store mode makes all container metadata be saved in temporary storage
(i.e. runroot above). This is faster, but doesn't persist across reboots.
Additional garbage collection must also be performed at boot-time, so this option should remain disabled in most configurations. (default: false)
### STORAGE OPTIONS TABLE
The `storage.options` table supports the following options:
@ -71,7 +84,7 @@ 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.
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
@ -93,24 +106,10 @@ containers/storage supports four keys
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"
* convert_images = "false" | "true"
If set to true, containers/storage will convert images to a format compatible with
partial pulls in order to take advantage of local deduplication and hardlinking. It is an
expensive operation so it is not enabled by default.
**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.
@ -141,66 +140,6 @@ The `storage.options.btrfs` table supports the following options:
**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:
@ -261,6 +200,9 @@ based file systems.
**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: <number>[<unit>], where unit = b (bytes), k (kilobytes), m (megabytes), or g (gigabytes))
**use_composefs** = "false"
Use ComposeFS to mount the data layers image. ComposeFS support is experimental and not recommended for production use. (default: false)
### STORAGE OPTIONS FOR VFS TABLE
The `storage.options.vfs` table supports the following options:
@ -9,21 +9,23 @@ containers-transports - description of supported transports for copying and stor
## DESCRIPTION
Tools which use the containers/image library, including skopeo(1), buildah(1), podman(1), all share a common syntax for referring to container images in various locations.
The general form of the syntax is _transport:details_, where details are dependent on the specified transport, which are documented below.
The general form of the syntax is _transport_`:`_details_, where details are dependent on the specified transport, which are documented below.
The semantics of the image names ultimately depend on the environment where
they are evaluated. For example: if evaluated on a remote server, image names
might refer to paths on that server; relative paths are relative to the current
The format of _docker-reference_ is described in detail in the **docker** transport.
The _storage-specifier_ allows for referencing storage locations on the file system and has the format `[[driver@]root[+run-root][:options]]` where the optional `driver` refers to the storage driver (e.g., overlay or btrfs) and where `root` is an absolute path to the storage's root directory.
The optional `run-root` can be used to specify the run directory of the storage where all temporary writable content is stored.
The optional `options` are a comma-separated list of driver-specific options.
The _storage-specifier_ allows for referencing storage locations on the file system and has the format `[`[_driver_`@`]_root_[`+`_run-root_][`:`_options_]`]` where the optional _driver_ refers to the storage driver (e.g., `overlay` or `btrfs`) and where _root_ is an absolute path to the storage's root directory.
The optional _run-root_ can be used to specify the run directory of the storage where all temporary writable content is stored.
The optional _options_ are a comma-separated list of driver-specific options.
Please refer to containers-storage.conf(5) for further information on the drivers and supported options.
### **dir:**_path_
@ -38,43 +40,68 @@ By default, uses the authorization state in `$XDG_RUNTIME_DIR/containers/auth.js
If the authorization state is not found there, `$HOME/.docker/config.json` is checked, which is set using docker-login(1).
The containers-registries.conf(5) further allows for configuring various settings of a registry.
Note that a _docker-reference_ has the following format: `name[:tag|@digest]`.
Note that a _docker-reference_ has the following format: _name_[`:`_tag_ | `@`_digest_].
While the docker transport does not support both a tag and a digest at the same time some formats like containers-storage do.
Digests can also be used in an image destination as long as the manifest matches the provided digest.
The docker transport supports pushing images without a tag or digest to a registry when the image name is suffixed with `@@unknown-digest@@`. The _name_`@@unknown-digest@@` reference format cannot be used with a reference that has a tag or digest.
The digest of images can be explored with skopeo-inspect(1).
If `name` does not contain a slash, it is treated as `docker.io/library/name`.
Otherwise, the component before the first slash is checked if it is recognized as a `hostname[:port]` (i.e., it contains either a . or a :, or the component is exactly localhost).
If the first component of name is not recognized as a `hostname[:port]`, `name` is treated as `docker.io/name`.
If _name_ does not contain a slash, it is treated as `docker.io/library/`_name_.
Otherwise, the component before the first slash is checked if it is recognized as a _hostname_[`:`_port_] (i.e., it contains either a `.` or a `:`, or the component is exactly `localhost`).
If the first component of name is not recognized as a _hostname_[`:`_port_], _name_ is treated as `docker.io/`_name_.
Files in those locations are not loaded by default but only on-demand. They are loaded after all system and user configuration files but before `CONTAINERS_CONF_OVERRIDE` hence allowing for overriding system and user configs.
Modules are currently supported by podman(1). The `podman --module` flag allows for loading a module and can be specified multiple times. If the specified value is an absolute path, the config file will be loaded directly. Relative paths are resolved relative to the three module directories mentioned above and in the specified order such that modules in `$XDG_CONFIG_HOME/$HOME` allow for overriding those in `/etc` and `/usr/share`.
## APPENDING TO STRING ARRAYS
The default behavior during the loading sequence of multiple containers.conf files is to override previous data. To change the behavior from overriding to appending, you can set the `append` attribute as follows: `array=["item-1", "item=2", ..., {append=true}]`. Setting the append attribute instructs to append to this specific string array for the current and also subsequent loading steps. To change back to overriding, set `{append=false}`.
Consider the following example:
```
modules1.conf: env=["1=true"]
modules2.conf: env=["2=true"]
modules3.conf: env=["3=true", {append=true}]
modules4.conf: env=["4=true"]
```
After loading the files in the given order, the final contents are `env=["2=true", "3=true", "4=true"]`. If modules4.conf would set `{append=false}`, the final contents would be `env=["4=true"]`.
# FORMAT
The [TOML format][toml] is used as the encoding of the configuration file.
Every option is nested under its table. No bare options are used. The format of
@ -50,6 +84,7 @@ TOML can be simplified to:
The containers table contains settings to configure and manage the OCI runtime.
**annotations** = []
List of annotations. Specified as "key=value" pairs to be added to all containers.
Example: "run.oci.keep_original_groups=1"
@ -66,6 +101,12 @@ file. This must be either an absolute path or as special values "image" which
uses the hosts file from the container image or "none" which means
no base hosts file is used. The default is "" which will use /etc/hosts.
**cgroup_conf**=[]
List of cgroup_conf entries specifying a list of cgroup files to write to and
their values. For example `memory.high=1073741824` sets the
memory.high limit to 1GB.
**cgroups**="enabled"
Determines whether the container will create CGroups.
@ -76,7 +117,7 @@ Options are:
**cgroupns**="private"
Default way to to create a cgroup namespace for the container.
Default way to create a cgroup namespace for the container.
Options are:
`private` Create private Cgroup Namespace for the container.
`host` Share host Cgroup Namespace with the container.
@ -98,12 +139,12 @@ default_capabilities = [
"SETGID",
"SETPCAP",
"SETUID",
"SYS_CHROOT",
]
```
Note, by default container engines using containers.conf, run with less
capabilities than Docker. Docker runs additionally with "AUDIT_WRITE", "MKNOD",
"NET_RAW", "CHROOT". If you need to add one of these capabilities for a
capabilities than Docker. Docker runs additionally with "AUDIT_WRITE", "MKNOD" and "NET_RAW". If you need to add one of these capabilities for a
particular container, you can use the --cap-add option or edit your system's containers.conf.
**default_sysctls**=[]
@ -143,7 +184,7 @@ A list of dns servers to override the DNS configuration passed to the
container. The special value “none” can be specified to disable creation of
Environment variable list for the container process, used for passing
environment variables to the container.
@ -177,13 +218,24 @@ Run an init inside the container that forwards signals and reaps processes.
**init_path**="/usr/libexec/podman/catatonit"
If this option is not set catatonit is searched in the directories listed under
the **helper_binaries_dir** option. It is recommended to just install catatonit
there instead of configuring this option here.
Path to the container-init binary, which forwards signals and reaps processes
within containers. Note that the container-init binary will only be used when
the `--init` for podman-create and podman-run is set.
**interface_name**=""
Default way to set interface names inside containers. Defaults to legacy pattern
of ethX, where X is an integer, when left undefined.
Options are:
`device` Uses the network_interface name from the network config as interface name. Falls back to the ethX pattern if the network_interface is not set.
**ipcns**="shareable"
Default way to to create a IPC namespace for the container.
Default way to create a IPC namespace for the container.
Options are:
`host` Share host IPC Namespace with the container.
`none` Create shareable IPC Namespace for the container without a private /dev/shm.
@ -199,6 +251,13 @@ the container.
Indicates whether the container engine uses MAC(SELinux) container separation via labeling. This option is ignored on disabled systems.
**label_users**=false
label_users indicates whether to enforce confined users in containers on
SELinux systems. This option causes containers to maintain the current user
and role field of the calling process. By default SELinux containers run with
the user system_u, and the role system_r.
**log_driver**=""
Logging driver for the container. Currently available options are k8s-file, journald, none and passthrough, with json-file aliased to k8s-file for scripting compatibility. The journald driver is used by default if the systemd journal is readable and writable. Otherwise, the k8s-file driver is used.
@ -214,9 +273,16 @@ limit is never exceeded.
Default format tag for container log messages. This is useful for creating a specific tag for container log messages. Container log messages default to using the truncated container ID as a tag.
**mounts**=[]
List of mounts.
Specified as "type=TYPE,source=<directory-on-host>,destination=<directory-in-container>,<options>"
Default way to to create a NET namespace for the container.
Default way to create a NET namespace for the container.
Options are:
`private` Create private NET Namespace for the container.
`host` Share host NET Namespace with the container.
@ -227,9 +293,13 @@ Options are:
Create /etc/hosts for the container. By default, container engines manage
/etc/hosts, automatically adding the container's own IP address.
**oom_score_adj**=0
Tune the host's OOM preferences for containers (accepts values from -1000 to 1000).
**pidns**="private"
Default way to to create a PID namespace for the container.
Default way to create a PID namespace for the container.
Options are:
`private` Create private PID Namespace for the container.
`host` Share host PID Namespace with the container.
@ -243,6 +313,12 @@ is imposed.
Copy the content from the underlying image into the newly created volume when the container is created instead of when it is started. If `false`, the container engine will not copy the content until the container is started. Setting it to `true` may have negative performance implications.
**privileged**=false
Give extended privileges to all containers. A privileged container turns off the security features that isolate the container from the host. Dropped Capabilities, limited devices, read-only mount points, Apparmor/SELinux separation, and Seccomp filters are all disabled. Due to the disabled security features, the privileged field should almost never be set as containers can easily break out of confinment.
Containers running in a user namespace (e.g., rootless containers) cannot have more privileges than the user that launched them.
**read_only**=true|false
Run all containers with root file system mounted read-only. Set to false by default.
@ -276,14 +352,14 @@ Sets umask inside the container.
**userns**="host"
Default way to to create a USER namespace for the container.
Default way to create a USER namespace for the container.
Options are:
`private` Create private USER Namespace for the container.
`host` Share host USER Namespace with the container.
**utsns**="private"
Default way to to create a UTS namespace for the container.
Default way to create a UTS namespace for the container.
Options are:
`private` Create private UTS Namespace for the container.
`host` Share host UTS Namespace with the container.
@ -324,6 +400,20 @@ cni_plugin_dirs = [
]
```
**netavark_plugin_dirs**=[]
List of directories that will be searched for netavark plugins.
The default list is:
```
netavark_plugin_dirs = [
"/usr/local/libexec/netavark",
"/usr/libexec/netavark",
"/usr/local/lib/netavark",
"/usr/lib/netavark",
]
```
**default_network**="podman"
The network name of the default network to attach pods to.
@ -352,14 +442,26 @@ default_subnet_pools = [
]
```
**default_rootless_network_cmd**="pasta"
Configure which rootless network program to use by default. Valid options are
`slirp4netns` and `pasta` (default).
**network_config_dir**="/etc/cni/net.d/"
Path to the directory where network configuration files are located.
For the CNI backend the default is "/etc/cni/net.d" as root
and "$HOME/.config/cni/net.d" as rootless.
For the CNI backend the default is __/etc/cni/net.d__ as root
and __$HOME/.config/cni/net.d__ as rootless.
For the netavark backend "/etc/containers/networks" is used as root
and "$graphroot/networks" as rootless.
**firewall_driver**=""
The firewall driver to be used by netavark.
The default is empty which means netavark will pick one accordingly. Current supported
drivers are "iptables", "nftables", "none" (no firewall rules will be created) and "firewalld" (firewalld is
experimental at the moment and not recommend outside of testing).
**dns_bind_port**=53
Port to use for dns forwarding daemon with netavark in rootful bridge
@ -367,6 +469,11 @@ mode and dns enabled.
Using an alternate port might be useful if other dns services should
run on the machine.
**pasta_options** = []
A list of default pasta options that should be used running pasta.
It accepts the pasta cli options, see pasta(1) for the full list of options.
## ENGINE TABLE
The `engine` table contains configuration options used to set up container engines such as Podman and Buildah.
@ -374,11 +481,39 @@ The `engine` table contains configuration options used to set up container engin
Name of destination for accessing the Podman service. See SERVICE DESTINATION TABLE below.
**add_compression**=[]
List of compression algorithms. If set makes sure that requested compression variant
for each platform is added to the manifest list keeping original instance intact in
the same manifest list on every `manifest push`. Supported values are (`gzip`, `zstd` and `zstd:chunked`).
Note: This is different from `compression_format` which allows users to select a default
compression format for `push` and `manifest push`, while `add_compression` is limited to
`manifest push` and allows users to append new instances to manifest list with specified compression
algorithms in `add_compression` for each platform.
**cgroup_manager**="systemd"
The cgroup management implementation used for the runtime. Supports `cgroupfs`
and `systemd`.
**compat_api_enforce_docker_hub**=true
Enforce using docker.io for completing short names in Podman's compatibility
REST API. Note that this will ignore unqualified-search-registries and
short-name aliases defined in containers-registries.conf(5).
**compose_providers**=[]
Specify one or more external providers for the compose command. The first
found provider is used for execution. Can be an absolute and relative path or
a (file) name.
**compose_warning_logs**=true
Emit logs on each invocation of the compose command indicating that an external
compose provider is being executed.
**conmon_env_vars**=[]
Environment variables to pass into Conmon.
@ -403,6 +538,15 @@ conmon_path=[
]
```
**database_backend**=""
The database backend of Podman. Supported values are "" (default), "boltdb"
and "sqlite". An empty value means it will check whenever a boltdb already
exists and use it when it does, otherwise it will use sqlite as default
(e.g. new installs). This allows for backwards compatibility with older versions.
Please run `podman-system-reset` prior to changing the database
backend of an existing deployment, to make sure Podman can operate correctly.
**detach_keys**="ctrl-p,ctrl-q"
Keys sequence used for detaching a container.
@ -410,6 +554,7 @@ Specify the keys sequence used to detach a container.
Format is a single character `[a-Z]` or a comma separated sequence of
`ctrl-<value>`, where `<value>` is one of:
`a-z`, `@`, `^`, `[`, `\`, `]`, `^` or `_`
Specifying "" disables this feature.
**enable_port_reservation**=true
@ -437,7 +582,7 @@ The unit can be b (bytes), k (kilobytes), m (megabytes) or g (gigabytes).
The format for the size is `<number><unit>`, e.g., `1b` or `3g`.
If no unit is included then the size will be in bytes.
When the limit is exceeded, the logfile will be rotated and the old one will be deleted.
If the maximumn size is set to 0, then no limit will be applied,
If the maximum size is set to 0, then no limit will be applied,
Path to the OCI hooks directories for automatically executed hooks.
**cdi_spec_dirs**=["/etc/cdi", ...]
Directories to scan for CDI Spec files.
**image_default_format**="oci"|"v2s2"|"v2s1"
Manifest Type (oci, v2s2, or v2s1) to use when pulling, pushing, building
@ -502,7 +676,7 @@ Not setting this field will fall back to containers/image defaults. (6)
**image_volume_mode**="bind"
Tells container engines how to handle the builtin image volumes.
Tells container engines how to handle the built-in image volumes.
* bind: An anonymous named volume will be created and mounted into the container.
* tmpfs: The volume is mounted onto the container as a tmpfs, which allows the users to create content that disappears when the container is stopped.
@ -512,18 +686,22 @@ Tells container engines how to handle the builtin image volumes.
Infra (pause) container image command for pod infra containers. When running a
pod, we start a `/pause` process in a container to hold open the namespaces
associated with the pod. This container does nothing other then sleep,
reserving the pods resources for the lifetime of the pod.
associated with the pod. This container does nothing other than sleep,
reserving the pod's resources for the lifetime of the pod.
**infra_image**=""
Infra (pause) container image for pod infra containers. When running a
pod, we start a `pause` process in a container to hold open the namespaces
associated with the pod. This container does nothing other then sleep,
reserving the pods resources for the lifetime of the pod. By default container
engines run a builtin container using the pause executable. If you want override
associated with the pod. This container does nothing other than sleep,
reserving the pod's resources for the lifetime of the pod. By default container
engines run a built-in container using the pause executable. If you want override
specify an image to pull.
**kube_generate_type**="pod"
Default Kubernetes kind/specification of the kubernetes yaml generated with the `podman kube generate` command. The possible options are `pod` and `deployment`.
**lock_type**="shm"
Specify the locking mechanism to use; valid values are "shm" and "file".
@ -572,10 +750,11 @@ Whether to use chroot instead of pivot_root in the runtime.
**num_locks**=2048
Number of locks available for containers and pods. Each created container or
pod consumes one lock. The default number available is 2048. If this is
changed, a lock renumbering must be performed, using the
`podman system renumber` command.
Number of locks available for containers, pods, and volumes.
Each created container, pod, or volume consumes one lock.
Locks are recycled and can be reused after the associated container, pod, or volume is removed.
The default number available is 2048.
If this is changed, a lock renumbering must be performed, using the `podman system renumber` command.
**pod_exit_policy**="continue"
@ -595,16 +774,25 @@ Pull image before running or creating a container. The default is **missing**.
- **never**: do not pull the image from the registry, use only the local version. Raise an error if the image is not present locally.
**remote** = false
Indicates whether the application should be running in remote mode. This flag modifies the
--remote option on container engines. Setting the flag to true will default `podman --remote=true` for access to the remote Podman service.
**retry** = 3
Number of times to retry pulling/pushing images in case of failure.
**retry_delay** = ""
Delay between retries in case pulling/pushing image fails. If set, container engines will retry at the set interval, otherwise they delay 2 seconds and then exponentially back off.
**runtime**=""
Default OCI specific runtime in runtimes that will be used by default. Must
refer to a member of the runtimes table. Default runtime will be searched for
on the system using the priority: "crun", "runc", "kata".
on the system using the priority: "crun", "runc", "runj", "kata", "runsc", "ocijail"
@ -721,13 +919,13 @@ The size of the disk in GB created when init-ing a podman-machine VM
**image**=""
Default image URI when creating a new VM using `podman machine init`.
Options: On Linux/Mac, `testing`, `stable`, `next`. On Windows, the major
version of the OS (e.g `36`) for Fedora 36. For all platforms you can
alternatively specify a custom download URL to an image. Container engines
translate URIs $OS and $ARCH to the native OS and ARCH. URI "https://example.com/$OS/$ARCH/foobar.ami" would become "https://example.com/linux/amd64/foobar.ami" on a Linux AMD machine.
The default value
is `testing` on Linux/Mac, and on Windows.
Image used when creating a new VM using `podman machine init`.
Can be specified as a registry with a bootable OCI artifact, download URL, or a local path.
Registry target must be in the form of `docker://registry/repo/image:version`.
Container engines translate URIs $OS and $ARCH to the native OS and ARCH.
URI "https://example.com/$OS/$ARCH/foobar.ami" would become
"https://example.com/linux/amd64/foobar.ami" on a Linux AMD machine.
If unspecified, the default Podman machine image will be used.
**memory**=2048
@ -745,29 +943,71 @@ Environment variables like $HOME as well as complete paths are supported for
the source and destination. An optional third field `:ro` can be used to
tell the container engines to mount the volume readonly.
On Mac, the default volumes are: `"/Users:/Users", "/private:/private", "/var/folders:/var/folders"`
Virtualization provider to be used for running a podman-machine VM. Empty value
is interpreted as the default provider for the current host OS. On Linux/Mac
default is `QEMU` and on Windows it is `WSL`.
**rosetta**="true"
Rosetta supports running x86_64 Linux binaries on a Podman machine on Apple silicon.
The default value is `true`. Supported on AppleHV(arm64) machines only.
## FARMS TABLE
The `farms` table contains configuration options used to group up remote connections into farms that will be used when sending out builds to different machines in a farm via `podman buildfarm`.
**default**=""
The default farm to use when farming out builds.
**[farms.list]**
Map of farms created where the key is the farm name and the value is the list of system connections.
## PODMANSH TABLE
The `podmansh` table contains configuration options used by podmansh.
**shell**="/bin/sh"
The shell to spawn in the container.
The default value is `/bin/sh`.
**container**="podmansh"
Name of the container that podmansh joins.
The default value is `podmansh`.
**timeout**=0
Number of seconds to wait for podmansh logins. This value if favoured over the deprecated field `engine.podmansh_timeout` if set.
The default value is 30.
# FILES
**containers.conf**
Distributions often provide a `/usr/share/containers/containers.conf` file to
define default container configuration. Administrators can override fields in
this file by creating `/etc/containers/containers.conf` to specify their own
configuration. Rootless users can further override fields in the config by
creating a config file stored in the `$HOME/.config/containers/containers.conf` file.
If the `CONTAINERS_CONF` path environment variable is set, just
this path will be used. This is primarily used for testing.
Distributions often provide a __/usr/share/containers/containers.conf__ file to
provide a default configuration. Administrators can override fields in this
file by creating __/etc/containers/containers.conf__ to specify their own
configuration. They may also drop `.conf` files in
__/etc/containers/containers.conf.d__ which will be loaded in alphanumeric order.
For user specific configuration it reads __\$XDG_CONFIG_HOME/containers/containers.conf__ and
__\$XDG_CONFIG_HOME/containers/containers.conf.d/\*.conf__ files. When `$XDG_CONFIG_HOME` is not set it falls back to using `$HOME/.config` instead.
Fields specified in the containers.conf file override the default options, as
well as options in previously read containers.conf files.
Fields specified in a containers.conf file override the default options, as
well as options in previously loaded containers.conf files.
**storage.conf**
The `/etc/containers/storage.conf` file is the default storage configuration file.
Rootless users can override fields in the storage config by creating
`$HOME/.config/containers/storage.conf`.
__$HOME/.config/containers/storage.conf__.
If the `CONTAINERS_STORAGE_CONF` path environment variable is set, this path
is used for the storage.conf file rather than the default.
