cannot unpack gzip'd layers

[cyphar]

Both oci-unpack and oci-create-runtime-bundle cannot unpack gzip'd layers. I haven't read what the spec says about compressed layers (and I know @vbatts has some strong opinions about it) but this is either an issue in skopeo or image-tools.

Specifically, the examples in the documentation don't work:

% skopeo copy docker://alpine:latest oci:alpine-oci
% oci-unpack --ref latest alpine-oci alpine-unpack
unpacking failed: invalid layer media type: invalid media type "application/vnd.oci.image.layer.v1.tar+gzip"
% oci-create-runtime-bundle --ref latest alpine-oci alpine-unpack
unpacking failed: invalid layer media type: invalid media type "application/vnd.oci.image.layer.v1.tar+gzip"

Pinging @runcom since it involves skopeo and might be a problem there (but IMO we shouldn't be regenerating new blob IDs on the fly inside skopeo). I'd be happy to work on a PR for image-tools if it's an issue of compressed unpacking not having been implemented yet. 😉

[cyphar]

I figured it out, it's because we haven't vendor'd opencontainers/image-spec#347 yet. And it turns out there's already a PR which fixes it #56.

[runcom]

@cyphar is this a non-issue then?

[cyphar]

I'll leave it open until #56 is merged. Sorry for pinging you, I thought it was related to the whole "compression breaks content-addressability" stuff that @vbatts always goes on about. 😉