How to integrate Docker with CI/CD pipelines?

· Category: Docker

Short answer

Integrate Docker into CI/CD by building images in the pipeline, running tests inside containers, scanning for vulnerabilities, and pushing approved images to a registry.

Steps

  1. Clone the repository.
  2. Build the Docker image.
  3. Run unit and integration tests in containers.
  4. Scan the image for security issues.
  5. Push to a registry on the main branch.

Example

# GitHub Actions example
- name: Build image
  run: docker build -t myapp:${{ github.sha }} .

- name: Run tests
  run: docker run --rm myapp:${{ github.sha }} pytest

- name: Push image
  if: github.ref == 'refs/heads/main'
  run: |
    docker login -u ${{ secrets.DOCKER_USER }} -p ${{ secrets.DOCKER_PASS }}
    docker push myapp:${{ github.sha }}

Tips

  • Use Docker layer caching in CI to speed up builds.
  • Run tests in the same image that will be deployed.
  • Tag images with the commit SHA for traceability.

Common issues

  • Docker-in-Docker requires privileged runners.
  • Large images slow down CI; optimize with multi-stage builds.
  • Registry authentication tokens may expire during long pipelines.