wait-for-docker-image-action

This is an action to ensure a Docker image is available at the current Git revision. It is useful for an end-to-end test with docker build in GitHub Actions.

Problem to solve

For building and testing a Docker image in GitHub Actions, typical workflow would be like:

1. Build job
2. Test job (after build)

However, if the test job takes a long time to prepare an environment, it would be nice to run build and prepare in parallel. For example,

• Install packages using apt-get install
• Create a Kubernetes cluster using kind
• Deploy components using kubectl

The workflow can be run in parallel, like:

• Build job
• Test job
  1. Prepare an environment
  2. Wait for the image (this action provides this step)
  3. Run the test

This action waits until org.opencontainers.image.revision annotation of the Docker image is the current Git revision. You can generate OCI annotations using docker/metadata-action.

Example

Here is an example workflow. It builds an Docker image and tests it.

name: e2e-test

jobs:
  build:
    runs-on: ubuntu-latest
    timeout-minutes: 10
    steps:
      - uses: actions/checkout@v3
      - uses: docker/metadata-action@v4
        id: metadata
        with:
          images: ghcr.io/${{ github.repository }}
      - uses: docker/login-action@v2
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}
      - uses: docker/build-push-action@v3
        with:
          push: true
          tags: ${{ steps.metadata.outputs.tags }}
          labels: ${{ steps.metadata.outputs.labels }}

  test:
    runs-on: ubuntu-latest
    timeout-minutes: 10
    steps:
      - uses: actions/checkout@v3

      # Prepare a test environment,
      # for example, create a Kubernetes cluster or set up middlewares
      - run: make -C e2e-test setup

      # Wait for the image
      - uses: docker/metadata-action@v4
        id: metadata
        with:
          images: ghcr.io/${{ github.repository }}
      - uses: int128/wait-for-docker-image-action@v1
        with:
          tags: ${{ steps.metadata.outputs.tags }}

      # Write your test here
      - run: make -C e2e-test test
        env:
          TARGET_IMAGE: ${{ steps.metadata.outputs.tags }}

Specification

This actions depends on docker pull and docker image inspect command.

Inputs

Name	Default	Description
tags	(required)	Docker image tags
expected-revision	(see below)	Expected Git revisions of Docker image
timeout-seconds	600	Timeout
polling-seconds	5	Polling interval

By default, this action waits until the revision is github.sha or github.event.pull_request.head.sha. Since docker/metadata-action@v4.1.0, it generates the head sha on pull request event (see also the issue).