Workflow Docker Push

In this lesson, you’ll extend your GitHub Actions CI workflow to publish a Docker image to Docker Hub. We’ll build the image for testing, verify it runs correctly, and then push it to your Docker Hub registry—all within a single workflow file.

Updated Workflow Snippet

Add these three steps to your .github/workflows/ci.yml:

# 1. Build the Docker image without pushing
- name: Docker Build for Testing
  uses: docker/build-push-action@v4
  with:
    context: .
    push: false                   # disable push during test build
    tags: ${{ vars.DOCKERHUB_USERNAME }}/solar-system:${{ github.sha }}

# 2. Run tests against the local image
- name: Docker Image Testing
  run: |
    docker images
    docker run --name solar-system-app -d \
      -p 3000:3000 \
      -e MONGO_URI=${{ secrets.MONGO_URI }} \
      -e MONGO_USERNAME=${{ secrets.MONGO_USERNAME }} \
      -e MONGO_PASSWORD=${{ secrets.MONGO_PASSWORD }} \
      ${{ vars.DOCKERHUB_USERNAME }}/solar-system:${{ github.sha }}

    # Inspect container IP and test /live endpoint
    IP=$(docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' solar-system-app)
    echo "Container IP: $IP"
    echo "Testing /live endpoint"
    wget -qO- "http://127.0.0.1:3000/live" | grep live

# 3. Push the tested image to Docker Hub
- name: Docker Push
  uses: docker/build-push-action@v4
  with:
    context: .
    push: true                    # enable push to registry
    tags: ${{ vars.DOCKERHUB_USERNAME }}/solar-system:${{ github.sha }}

After you commit and push, GitHub Actions will execute the build, test, and push steps in sequence.

Step-by-Step Breakdown

Inspecting the Push Logs

During the Docker Push step you’ll see output similar to:

/usr/bin/docker buildx build \
  --iidfile /tmp/docker-actions-toolkit/iidfile \
  --tag youruser/solar-system:e8095fb98a5b01249548095eaf3a9c371c274430 \
  --push .

This confirms that Buildx is pushing each layer of your image to Docker Hub.

Verify the Image on Docker Hub

Once the workflow completes:

1. Go to your repository on Docker Hub.
2. Look under Tags for the SHA-based tag (e.g., e8095fb98a5b01249548095eaf3a9c371c274430).

Manual Push (Optional)

You can also push an existing local image with:

docker push youruser/solar-system:tagname

Links and References

• GitHub Actions: build-push-action
• Docker Hub
• GitHub Secrets Documentation