containers-storage:[[storage-specifier]]{image-id|docker-reference[@image-id]}

An image located in a local containers storage. 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. Please refer to containers-storage.conf(5) for further information on the drivers and supported options.

dir:path

An existing local directory path storing the manifest, layer tarballs and signatures as individual files. This is a non-standardized format, primarily useful for debugging or noninvasive container inspection.

docker://docker-reference

An image in a registry implementing the "Docker Registry HTTP API V2". By default, uses the authorization state in $XDG_RUNTIME_DIR/containers/auth.json, which is set using podman-login(1). 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]. 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 ⟨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.

docker-archive:path[:{docker-reference|@source-index}]

An image is stored in the docker-save(1) formatted file.

Unless a tool explicitly documents otherwise, a write to a docker-archive: destination completely overwrites path, replacing it with the single provided image.

The path can refer to a stream, e.g. docker-archive:/dev/stdin.

docker-reference must not contain a digest. Alternatively, for reading archives, @source-index is a zero-based index in archive manifest (to access untagged images). If neither docker-reference nor @_source_index is specified when reading an archive, the archive must contain exactly one image.

docker-daemon:docker-reference|algo:digest

An image stored in the docker daemon's internal storage. The image must be specified as a docker-reference or in an alternative algo:digest format when being used as an image source. The algo:digest refers to the image ID reported by docker-inspect(1).

oci:path[:reference]

An image in a directory structure compliant with the "Open Container Image Layout Specification" at path.

The path value terminates at the first : character; any further : characters are not separators, but a part of reference. The reference is used to set, or match, the org.opencontainers.image.ref.name annotation in the top-level index. If reference is not specified when reading an image, the directory must contain exactly one image.

oci-archive:path[:reference]

An image in a tar(1) archive with contents compliant with the "Open Container Image Layout Specification" at path.

Unless a tool explicitly documents otherwise, a write to an oci-archive: destination completely overwrites path, replacing it with the single provided image.

The path value terminates at the first : character; any further : characters are not separators, but a part of reference. The reference is used to set, or match, the org.opencontainers.image.ref.name annotation in the top-level index. If reference is not specified when reading an archive, the archive must contain exactly one image.

ostree:docker-reference[@/absolute/repo/path]

An image in the local ostree(1) repository. /absolute/repo/path defaults to /ostree/repo.

sif:path

An image using the Singularity image format at path.

Only reading images is supported, and not all scripts can be represented in the OCI format.