Now that you've learned about GitLab like Pipelines, Runners, Variables & Secrets, and Artifacts, it’s time to bring it all together in a practical, real-world project. 🎯

In this project, you’ll:

✅ Build a Docker image of a Node.js app
✅ Push it securely to Docker Hub
✅ Automatically deploy it on your server using Docker Compose

Let’s get our hands dirty with some real DevOps action! 💻🐳

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🪜 Step-by-Step Workflow

✅ Step 1: Import Project in GitLab

Start by creating or importing a Node.js application into your GitLab repository.
You can use your own app or fork a public sample Node.js app (e.g., a To-Do app or REST API).

📍 GitLab UI → New Project → Import repository / Create blank project

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✅ Step 2: Set Up a Project-Specific Runner (Self-Hosted)

To run your pipeline jobs on your own infrastructure (not GitLab’s shared runners), you need a self-hosted runner.

🛠️ Install GitLab Runner on your Linux/Ubuntu server (EC2, GCP, or local VM):

sudo apt-get update
sudo apt-get install -y curl
curl -L https://packages.gitlab.com/install/repositories/runner/gitlab-runner/script.deb.sh | sudo bash
sudo apt-get install gitlab-runner

🔗 Then register the runner with your GitLab project:

sudo gitlab-runner register

Provide:

• GitLab URL

• Registration token (from GitLab → Settings → CI/CD → Runners)

• Description: this is self hosted runner

• Tags: linux

• Executor: shell or docker (depending on your setup). I'll go with shell.

📌 After registration, confirm that the runner is active and listed in your GitLab project under Settings → CI/CD → Runners.

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✅ Step 3: Add Secure Variables (Secrets)

To securely log in to Docker Hub, add your credentials as masked and protected variables in GitLab:

📍 Go to → Project → Settings → CI/CD → Variables

📌 These values will be injected securely into your pipeline and won’t appear in logs.

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🛠️ Step 4: Create .gitlab-ci.yml File

Now define your CI/CD pipeline steps using this GitLab configuration file:

stages:
  - build
  - test
  - push
  - deploy

build_job:
  stage: build
  script:
    - echo "Image building"
    - docker build -t node-cicd-app:latest .
  tags:
    - linux  

test_job:
  stage: test
  script:
    - echo "Test job running"
  tags:
    - linux

push_job:
  stage: push
  script:
    - echo "Push to Docker Hub"
    - echo "$DOCKERHUB_PASSWORD" | docker login -u "$DOCKERHUB_USER" --password-stdin
    - docker image tag node-cicd-app:latest $DOCKERHUB_USER/node-cicd-app:latest
    - docker push $DOCKERHUB_USER/node-cicd-app:latest
  tags:
    - linux

deploy_stage:
  stage: deploy
  script:
    - echo "Application Deployment"
    - docker compose up -d
  tags:
    - linux

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📘 Explanation of Each Stage

🔧 build_job
Builds a Docker image named node-cicd-app:latest from your Node.js source code.

🧪 test_job
Currently a placeholder. You can integrate tools like Jest, Mocha, or ESLint here later.

📦 push_job
Logs into Docker Hub securely using your secrets, tags the image, and pushes it to your Docker Hub repo.

🚀 deploy_stage
Runs docker compose up -d to deploy your app on the server. Make sure your docker-compose.yml is present in the project root.

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🎉 What This Setup Achieves

✅ Automated Build – Code changes instantly build new Docker images.
✅ Secure Credentials – Secrets are stored safely using masked variables.
✅ Push to DockerHub – Images are versioned and uploaded for portability.
✅ Deploy Automatically – No need to SSH into your server manually.

Every commit → builds → tests → pushes → deploys. 🧠👏

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🔐 Bonus Tip: Secure Docker Compose

If your docker-compose.yml includes environment variables (e.g., DB credentials), avoid committing them.
Use a .env file and add that as a GitLab CI/CD secret file for more security.

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📦 Optional: Add Artifacts

If your build_job generates logs, test reports, or binaries, you can save them as artifacts:

artifacts:
  paths:
    - build/
  expire_in: 1 week

This allows downloading or passing files to other stages like test or deploy.

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🧪 Real-Life Use Case

Imagine this scenario:

• You're building a microservice in Node.js

• Every push builds a Docker image and stores it on Docker Hub

• A remote server automatically pulls and runs the latest version using Compose

You just built a mini DevOps pipeline like big companies use! 🚀🔥

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✅ Final Thoughts :

This project helps you:

✅ Practice real CI/CD with GitLab
✅ Use secrets securely
✅ Work with Docker, Compose, and automation
✅ Understand the full DevOps lifecycle

🚀 Keep experimenting. Keep optimizing. Because in DevOps—automation isn’t just a tool, it’s a mindset.