Part 1: Introduction to GitLab CI/CD – Getting Started

What You'll Learn in Part 1

In this first part, we'll cover:

? What GitLab CI/CD is and why it’s essential.

? Setting up your first pipeline.

? Understanding the .gitlab-ci.yml file in detail.

? Basics: Stages, Jobs, and Tasks.

? Where to place the .gitlab-ci.yml file.

? Running your first build job.

What is GitLab CI/CD?

GitLab CI/CD (Continuous Integration/Continuous Deployment) is an automated process for building, testing, and deploying applications. It allows teams to deliver high-quality software faster and more efficiently.

Why GitLab CI/CD?

? Built-in Integration: No need for third-party tools—fully integrated into GitLab.

? Automation: Reduces manual effort by automating builds, tests, and deployments.

? Scalability: Works for small teams and large enterprises alike.

? Improved Code Quality: Detects errors early through continuous testing.

Understanding the .gitlab-ci.yml File

What is the .gitlab-ci.yml file?

The .gitlab-ci.yml file is the heart of your GitLab CI/CD pipeline. It defines the pipeline stages, jobs, and tasks to automate software delivery.

Where to Place the .gitlab-ci.yml File?

You must place this file at the root of your GitLab repository. Example:

my-project/
│── src/
│── tests/
│── .gitlab-ci.yml  ? (Place it here)
│── README.md        

Once this file is committed and pushed, GitLab automatically detects and triggers the pipeline.

Key Concepts: Stages, Jobs, and Tasks

1?? Stages

Stages define the pipeline phases (e.g., build, test, deploy).

Example: yaml file

stages:
  - build
  - test
  - deploy        

Think of stages as a sequence of steps in your software pipeline.

2?? Jobs

Jobs define specific actions performed within each stage.

Example: yaml file

build_job:
  stage: build
  script:
    - echo "Building the application..."        

A job is a unit of work that executes within a stage.

3?? Tasks (Commands within Jobs)

Tasks are commands that a job executes.

Example: yaml file

script:
  - npm install
  - npm run build        

Tasks are individual commands inside a job that do actual work.

Your First .gitlab-ci.yml File

Here’s a basic pipeline with build, test, and deploy stages.

Example: yaml file

stages:
  - build
  - test
  - deploy

build_job:
  stage: build
  script:
    - echo "Installing dependencies..."
    - npm install
    - echo "Building the application..."
    - npm run build

test_job:
  stage: test
  script:
    - echo "Running tests..."
    - npm run test

deploy_job:
  stage: deploy
  script:
    - echo "Deploying application..."
    - scp -r dist/ user@server:/var/www/html
  only:
    - main        

Breakdown of this Example:

? Stages: Defines the pipeline structure (build → test → deploy).

? Jobs: Defines specific steps like build_job, test_job, deploy_job.

? Script: Commands that execute inside each job.

? Only Main: Ensures deployment happens only on the main branch.

Triggering Your First Pipeline

Step 1: Commit and Push the .gitlab-ci.yml File

Once you push this file to GitLab, it automatically triggers the pipeline.

Step 2: View Your Pipeline

1?? Navigate to CI/CD → Pipelines in GitLab.

2?? Click on the running pipeline to see logs and job status.

Step 3: Manually Trigger a Pipeline (If Needed)

If you want to manually trigger a pipeline:

1?? Go to CI/CD → Pipelines

2?? Click Run Pipeline

Useful GitLab CI/CD Commands

See below shell (sh) commands:

?? Check Pipeline Status:

gitlab-runner status        

?? View Logs of a Job:

gitlab-runner logs        

?? Retry a Failed Job:

gitlab-runner retry <job_id>        

?? Cancel a Running Job:

gitlab-runner cancel <job_id>        

Summary Table: Where to Run GitLab CI/CD Commands:

Use Case: Automating Unit Tests

Imagine you’re working on a web application. You want to ensure every commit is automatically tested.

?? Without CI/CD: Developers manually run npm test, which is time-consuming.

?? With GitLab CI/CD: Every push triggers automated unit tests:

Example: yaml file

test_job:
  stage: test
  script:
    - echo "Running automated tests..."
    - npm run test        

Now, every push ensures your application remains bug-free automatically!

What's Next?

This is just the beginning! ?? In Part 2, we’ll explore intermediate features of GitLab CI/CD, such as caching, artifacts, environment variables, and deploying to staging environments.

#GitLab #CI/CD #DevOps #Automation #GitLabCI