source: imageblob source implementation by tonistiigi · Pull Request #4286 · moby/buildkit (original) (raw)

Image blob source in LLB allows addressing a single blob from a container image registry. The difference from the image source is that image source needs to point to a manifest that internally points to an array of layer blobs that are all extracted on top of each other to form a root FS. Contrary, image blob points to a single blob that is not extracted but downloaded as a single file into an empty snapshot, similarily how the HTTP source works.

The main use case for this source is to pin snapshots of HTTP URLs, upload the downloaded blob into container registry, and then use a source policy to map a HTTP URL (whose content might be changed) to the copy of the source as image blob to ensure immutability.

Signed-off-by: Tonis Tiigi tonistiigi@gmail.com