Actions Container image is misinterpreted when using own registry with short oci url

[FloThinksPi]

System information

• Operating System: MacOS
• Architecture: x64 (64-bit)
• Apple M1: no
• Docker version: 20.10.8
• act version: act version 0.2.24

Expected behaviour

Pulls the correct image

Actual behaviour

Adds docker.io to the image which already has a private repo specified and thus the url is invalid.

Workflow and/or repository

workflow

jobs:
  myjob:
    runs-on: [self-hosted, linux]
    name: test job
    container:
      image: myregistry:50000/ubuntu:20.04

Steps to reproduce

Create workflow with custom container image in job step(see workflow file above).
Watch pull fail.

act output

If i just do a act without verbose i get:

[Run database tests/Run psql db tests] 🚀  Start image=myregistry:50000/ubuntu:20.04
Error: invalid reference format

So image pull URL looks fine.

However if i do act -vvv on the same workflow i get:

[Run database tests/Run psql db tests]   🐳  docker pull myregistry:50000/ubuntu:20.04
DEBU[0000] Image exists? false                          
[Run database tests/Run psql db tests] pulling image 'docker.io/myregistry:50000/ubuntu:20.04' ()
DEBU[0000] invalid reference format                     

So here one can see it puts a docker.io in front of the already complete OCI Resource URL.
Then it fails as this obviously is not allowed.

[FloThinksPi]

It seems to work if i use:
myrepo:50000/library/ubuntu:20.04
Then the correct image is pulled.

I think act has some logic in it that interprets myrepo:50000/ubuntu:20.04 as myrepo:50000 beeing the username and ubuntu beeing the image and 20.04 beeing the tag. So it appends docker.io as registry url then.

However Docker pull on myrepo:50000/ubuntu:20.04 works as expected though and pulls the right image(which long url would be myrepo:50000/library/ubuntu:20.04). So i think it is actually wanted to pull the image that the container runtime would pull. So to interpret myrepo:50000 as url and not as username in that case.

[catthehacker]

act/pkg/container/docker_pull.go

Lines 100 to 109 in 6e5bd24

	func cleanImage(image string) string {
	imageParts := len(strings.Split(image, "/"))
	if imageParts == 1 {
	image = fmt.Sprintf("docker.io/library/%s", image)
	} else if imageParts == 2 {
	image = fmt.Sprintf("docker.io/%s", image)
	}
	return image
	}