Annotations let you specify arbitrary metadata for OCI image components, such as manifests, indexes, and descriptors.
To add annotations when building images with GitHub Actions, use the
metadata-action to automatically create OCI-compliant annotations. The
metadata action creates an annotations output that you can reference, both
with build-push-action and bake-action.
Configure annotation level
By default, annotations are placed on image manifests. To configure the
annotation level, set
the DOCKER_METADATA_ANNOTATIONS_LEVELS environment variable on the
metadata-action step to a comma-separated list of all the levels that you
want to annotate. For example, setting DOCKER_METADATA_ANNOTATIONS_LEVELS to
index results in annotations on the image index instead of the manifests.
The following example creates annotations on both the image index and manifests.
NoteThe build must produce the components that you want to annotate. For example, to annotate an image index, the build must produce an index. If the build produces only a manifest and you specify
indexorindex-descriptor, the build fails.
