Introduction to GitLab & CI/CD Concepts

The DevOps Approach

DevOps combines development and operations to deliver software faster and more reliably. It breaks down silos between teams and emphasizes automation.

The DevOps Lifecycle

Plan → Create → Verify → Package → Release → Configure → Monitor
  ↑                                                          |
  └──────────────────────────────────────────────────────────┘

CI/CD Explained

Term	Meaning	Automation Level
CI (Continuous Integration)	Build and test on every commit	Automated testing
CD (Continuous Delivery)	Ready to deploy at any time	Manual deploy trigger
CD (Continuous Deployment)	Auto-deploy to production	Fully automated

CI Pipeline Example

Push Code → Build → Unit Tests → Integration Tests → Package

CD Pipeline Example

Package → Deploy to Staging → Acceptance Tests → Deploy to Production

What is GitLab?

GitLab is an integrated DevOps platform that provides:

Source code management (like GitHub)
CI/CD pipelines (built-in)
Container registry
Issue tracking
Security scanning
Deployment environments

GitLab vs GitHub

Feature	GitLab	GitHub
CI/CD	Built-in (GitLab CI)	GitHub Actions
Registry	Integrated container registry	GitHub Packages
Self-hosted	Free (Community Edition)	Enterprise only
DevOps focus	Full lifecycle	Code-centric

GitLab CI Components

Component	Role
`.gitlab-ci.yml`	Pipeline configuration file
Runner	Machine that executes jobs
Pipeline	Collection of jobs organized in stages
Stage	Group of jobs that run in parallel
Job	Individual task (build, test, deploy)
Artifact	Files produced by jobs

How It Works

Developer pushes code
    → GitLab detects .gitlab-ci.yml
    → Pipeline is created
    → Runner picks up jobs
    → Jobs execute in stages
    → Results reported back

GitLab Runners

Runners are agents that execute CI/CD jobs. Types:

Type	Scope	Use Case
Shared	All projects	GitLab.com default
Group	All projects in a group	Team-wide
Specific	Single project	Custom environments

Executor Types

Executor	Description
Shell	Runs commands directly on the runner machine
Docker	Runs jobs inside Docker containers
Kubernetes	Runs jobs as Kubernetes pods

Creating a GitLab Project

Sign up at gitlab.com
Click New Project → Create blank project
Name it, set visibility, check "Initialize with README"
Click Create project

Summary

DevOps combines development and operations for faster delivery
CI automates building/testing; CD automates deployment
GitLab provides an integrated platform for the entire lifecycle
.gitlab-ci.yml defines your pipeline configuration
Runners execute the jobs defined in your pipeline
Stages organize jobs; jobs within a stage run in parallel

Next Steps

Next, we'll write .gitlab-ci.yml files and configure complete CI/CD pipelines.

Learning Objectives