action.yml

name: "Docker Tag Release"
description: "Given an existing image, applies the given tag and updates latest."

inputs:
  registry_username:
    description: >-
      Username for logging in to registry. Normally, set to github.actor.
    default: ${{ github.actor }}
  registry_token:
    description: >-
      Token for logging in to registry. Normally, use secrets.GITHUB_TOKEN.
    required: true
  registry:
    description: >-
      Registry that hosts these images; by default, ghcr.io.
    default: ghcr.io
  existing_tag:
    description: >-
      Existing image and tag to use.
    default: ${{ github.sha }}
  image:
    description: >-
      Image to tag, e.g. ghcr.io/organization/image.
    required: true
  new_tag:
    description: -> Tag to apply to image
    required: true
  wait_time:
    description: -> Time to wait between checking whether the image exists
    default: 60
  max_tries:
    description: -> Maximum number of times to check whether the image exists before giving up
    default: 10

runs:
  using: composite
  steps:
  - name: Log into container registry
    uses: docker/login-action@v3
    with:
      registry: ${{ inputs.registry }}
      username: ${{ inputs.registry_username }}
      password: ${{ inputs.registry_token }}

  - name: Wait for revision to exist in container registry
    env:
      EXISTING_TAG: ${{ inputs.existing_tag }}
      MAX_TRIES: ${{ inputs.max_tries }}
      WAIT_TIME: ${{ inputs.wait_time }}
    id: image_wait
    shell: bash
    run: |
      i=1
      while [ true ]; do
        echo "Checking if $EXISTING_TAG exists; try $i"
        if docker manifest inspect $EXISTING_TAG > /dev/null; then
          echo $EXISTING_TAG exists
          exit 0
        elif [ $i -lt $MAX_TRIES ]; then
          echo "Waiting $WAIT_TIME seconds"
          sleep $WAIT_TIME
          i=$((i+1))
        else
          echo "Image not found; giving up"
          exit 1
        fi
      done

  - name: Tag image release in GHCR
    env:
      EXISTING_TAG: ${{ inputs.existing_tag }}
      IMAGE: ${{ inputs.image }}
      NEW_TAG: ${{ inputs.new_tag }}
    shell: bash
    run: |
      docker buildx imagetools create \
            --tag  "$IMAGE":"$NEW_TAG" \
            --tag "$IMAGE":latest \
            "$EXISTING_TAG"