Run a job in a container, with an image built in a previous job

README.md

Run a job in a container with a previously built image

This workflow shows how to use a GitHub Action job output as a variable for another job container image. It will build a simple Docker image, tag it with the commit short SHA, push it to Docker Hub, then run a job in it.

Why?

In job.<job_id>.container.image, the env context is not available, but we can use outputs.

Note

If your docker metadata action returns multiple tags, I don't know how this would behave.

Instead of using ${{ needs.build.outputs.image_tag }}, you can use anything, for example:

job:
  job1:
    outputs:
      my_output: ${{ steps.vars.outputs.sha_short }}
    steps:
      - id: vars
        run: echo "sha_short=$(git rev-parse --short HEAD)" >> $GITHUB_OUTPUT

Dockerfile

FROM alpine:latest
RUN echo 'Do I exist?' > /test.txt

workflow.yaml

name: Docker
on:
  workflow_dispatch:
  push:
    branches: [ "main" ]

env:
  REPOSITORY: your-docker-hub-namespace/your-docker-hub-repository

jobs:
  build:
    runs-on: ubuntu-latest
    outputs:
      # This is what we are going to use to run the next job in our new image
      image_tag: ${{ steps.meta.outputs.tags }}
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4

      - name: Log in to Docker Hub
        if: github.event_name != 'pull_request'
        uses: docker/login-action@f4ef78c080cd8ba55a85445d5b36e214a81df20a
        with:
          username: ${{ vars.DOCKER_USERNAME }}
          password: ${{ secrets.DOCKER_TOKEN }}

      - name: Extract Docker metadata
        id: meta
        uses: docker/metadata-action@9ec57ed1fcdbf14dcef7dfbe97b2010124a938b7
        with:
          images: ${{ env.REPOSITORY }}
          tags: type=sha,prefix=

      - run: echo "steps.meta.outputs.tags = ${{ steps.meta.outputs.tags }}"

      - name: Build and push Docker image
        uses: docker/build-push-action@3b5e8027fcad23fda98b2e3ac259d8d67585f671
        with:
          context: .
          push: ${{ github.event_name != 'pull_request' }}
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}

  test:
    runs-on: ubuntu-latest
    needs: build
    container:
      image: ${{ needs.build.outputs.image_tag }}
    steps:
      - name: Does this look like your image?
        run: ls -l /

      - name: Assert that our test file is here
        run: test "$(cat /test.txt)" == "Do I exist?"