frozen tulip
I'm working on a fun side project (hoping to show a demo soon :), but running into a limitation of the Dagger API: namely access to the raw config and layers of a pulled image. The only available option I can see is { container { export } } which is not ideal since it goes through the host filesystem.
Any guidance here? Are there any size/small contributions I could make, or is it all large and complicated?
Thanks!
cc @ivory rover @gusty tiger 😇
gusty tiger
On the server-side we already have code that converts a Container->Config bytes: https://github.com/sipsma/dagger/blob/96548e8eaa25becc78bf807d567ab26a0e5a6b19/core/container.go#L1029-L1029
I'm not sure if that has all of the information you need, but seems like a good chunk of it at least.
So I think we could add an API call to Container that returns a struct with all that information. Basically a graphql schema that mirrors the oci image spec?
frozen tulip
I’m not 100% sure what I need yet.. For now I’ll take every lead I can get 🙂
This is to implement my docker2dagger adapter
So potentially anything a docker client might get from the engine API, I may need
In particular I would love to implement image import/export, save/load since pack relies on it
also image digests may need the exact imageconfig bytestream? Although in my first experiments the clients don’t seem to check those digests
gusty tiger
I see (the adapter will be super cool btw, looking forward to it), I think the devil will probably be in the details and I'm not very familiar with the details of what the docker engine provides. But I can't imagine there would be data that's totally inaccessible; there may be cases where we need to modify buildkit upstream to expose something but that's easier than ever since we can upgrade whenever we want.
Also, random thought in case you haven't looked at it already, nerdctl claims to be mostly compatible with the docker cli while using containerd+buildkit as a backend: https://github.com/containerd/nerdctl
Wonder if they dealt with the same issue
gusty tiger
“containerd+” is a major difference though
Oh totally, the code might just be useful inspo if nothing else