Custom builder should be able to return image digest

[maxmiles39]

For customized build, user is responsible for build and publish the image. Skaffold do not need to do the extra validation, or user should be able to disable it. Otherwise, user have to make the extra configuration to allow skaffold to access the image, for example, we need to make the registry public accessible.

Expected behavior

Skaffold skip the validation for customized build

Actual behavior

Skaffold is validating the image and extra config is required.
.

Information

• Contents of skaffold.yaml:

apiVersion: skaffold/v2beta4
kind: Config
build:
  tagPolicy:
    sha256: {}
  artifacts:
  - image: internal-registry/skaffold-custom
    custom:
      buildCommand: ./build.sh

[MarlonGamez]

Hi @dwctua, when you get the chance, would you be able to share the error message you're seeing when trying to build and push without allowing skaffold access to the image registry? Thanks :)

[maxmiles39]

see error below after run skaffold dev

exiting dev mode because first build failed: couldn't build "internal-registry/skaffold-custom": getting image: GET https://index.docker.io/v2
/internal-registry/skaffold-custom/manifests/latest: UNAUTHORIZED: authentication required; [map[Action:pull Class: Name:internal-registry/ska
ffold-custom Type:repository]]

[maxmiles39]

I updated the skaffold.yaml. the build.sh can be an empty file for the demo. the idea is let build.sh handle image build and push, but use skaffold as file watcher to trigger the build and re-deployment.

[MarlonGamez]

It looks like the error is coming from a caching related step of skaffold where we add a tag to the remote image. If you try to run skaffold with --cache-artifacts=false, does your issue still occur? I agree that skaffold shouldn't have to have access to the registry

[maxmiles39]

I'm still getting the same error by running command: skaffold run --cache-artifacts=false

[MarlonGamez]

Ah okay, thanks for trying it out. I'll bring this issue up in our team discussion soon 👍🏽

[tejal29]

@dwctua, skaffold needs to fetch the remote digest associated with the image to substitute all image names in the manifests.

One thing, we could do is, expose another environment variables where e.g. IMAGE_REF which custom builders can set for skaffold to fetch image remote id.

[maxmiles39]

I like the environment variable, this will remove the dependency for docker registry. As side note, Skaffold is using both tag and digest, it is also causing issue in openshift.

[MarlonGamez]

bumping the priority on this as I don't think our team has the bandwidth to push this through right now. PRs welcome!