Project 5: GitHub Actions - CI/CD Pipeline for a Containerised Application¶

Automate test, build, and deploy stages for a Flask application with a three-job GitHub Actions pipeline. View source on GitHub

Project Overview¶

This project demonstrates CI/CD fundamentals by building a GitHub Actions pipeline that runs automatically on every push to main. A Flask task-tracker API with ten unit tests provides real work for the pipeline to do: the test job runs pytest and flake8, the build job produces a Docker image pushed to GitHub Container Registry (GHCR) with both a SHA tag and :latest, and the deploy job spins up a Minikube cluster inside the runner, applies the Kubernetes manifests, waits for a healthy rollout, then runs a port-forward smoke test. Path filters ensure the pipeline only triggers when project files change, not on every portfolio commit.

  git push to main
        │
        ▼
┌─────────────────────────────────────────────────────────────┐
│                    GitHub Actions Runner                     │
│                                                             │
│  ┌─────────────────────────────────────────────────────┐   │
│  │  test job                                           │   │
│  │  pytest (10 tests) · flake8 lint                   │   │
│  └──────────────────────┬──────────────────────────────┘   │
│                         │ ✓ passes                          │
│                         ▼                                   │
│  ┌──────────────────┐       ┌──────────────────────────┐   │
│  │  build job       │──────►│  GHCR                    │   │
│  │                  │ push  │  flask-tasks:sha-abc1234  │   │
│  └──────────────────┘       │  flask-tasks:latest      │   │
│         │                   └──────────────────────────┘   │
│         │ ✓ image pushed                                    │
│         ▼                                                   │
│  ┌─────────────────────────────────────────────────────┐   │
│  │  deploy job                                         │   │
│  │  Minikube (in runner) ← kubectl apply               │   │
│  │  rollout status ✓  smoke test ✓                     │   │
│  └─────────────────────────────────────────────────────┘   │
└─────────────────────────────────────────────────────────────┘

Technology Stack¶

Key Features¶

• Three-job pipeline with explicit dependency chain: test → build → deploy
• Path-based trigger filters — pipeline runs only when project files change
• GHCR image push with dual tagging: immutable sha-<short> and mutable :latest
• GITHUB_TOKEN used for GHCR authentication — no external secrets required
• Minikube spun up inside GitHub Actions runner using medyagh/setup-minikube
• Image built directly into Minikube's Docker daemon, avoiding registry pull in CI
• Rolling update strategy with maxUnavailable: 0 for zero-downtime deploys
• Readiness and liveness probes on /health gate rollout completion
• Smoke test via kubectl port-forward validates the live deployment end-to-end
• build and deploy jobs skipped on pull requests — only test runs

Codebase Overview¶

project5-cicd-github-actions/
├── app/
│   ├── app.py            # Flask task-tracker: CRUD endpoints + /health
│   ├── test_app.py       # 10 pytest tests covering all routes and error cases
│   ├── requirements.txt  # Runtime dependency: flask==3.0.3
│   └── Dockerfile        # Python 3.11-slim image
├── k8s/
│   ├── deployment.yaml   # 2-replica Deployment with probes and resource limits
│   └── service.yaml      # NodePort Service: port 80 → 5000, nodePort 30090
└── README.md

# Workflow lives at the portfolio root:
.github/workflows/
└── project5-ci-cd.yml    # Three-job pipeline with path filters

Quick Start¶

Run tests locally (no cluster needed)¶

cd mini-projects/project5-cicd-github-actions/app

pip install flask==3.0.3 pytest flake8

# Run the test suite
pytest test_app.py -v

# Run the linter
flake8 . --max-line-length=100

Expected: 10 tests pass, 0 lint errors.

Trigger the CI/CD pipeline¶

Push any change to a file under mini-projects/project5-cicd-github-actions/ or to .github/workflows/project5-ci-cd.yml on main:

git add mini-projects/project5-cicd-github-actions/
git commit -m "Trigger Project 5 pipeline"
git push

Then watch the run at: https://github.com/christosm-dev/portfolio/actions

The pipeline runs three jobs in sequence: test → build → deploy. Pull requests run test only — build and deploy are skipped.

Inspect the published image¶

After a successful pipeline run, the image is available in GHCR:

docker pull ghcr.io/christosm-dev/flask-tasks:latest
docker run -p 5000:5000 ghcr.io/christosm-dev/flask-tasks:latest
curl http://localhost:5000/health

Run the app locally without the pipeline¶

cd mini-projects/project5-cicd-github-actions/app
flask --app app.py run
curl http://localhost:5000/tasks

Future Work¶

• Add a test coverage report published as a workflow artefact
• Push image to GHCR and configure an imagePullSecret for cluster auth
• Add a staging environment gate with manual approval before production deploy
• Implement semantic versioning with tags triggering release builds
• Cache pip and Docker layer builds between runs to reduce pipeline duration
• Add a security scan step (Trivy or Grype) between build and deploy jobs

Resources¶

• GitHub Actions Documentation
• docker/metadata-action
• docker/build-push-action
• medyagh/setup-minikube
• GitHub Container Registry Docs