What is GitLab CI/CD? A Complete Introduction to Continuous Integration and Delivery

GitLab CI/CD is an integrated system that allows development teams to automate the process of building, testing, and deploying their code. Unlike separate CI servers and deployment tools, GitLab provides a unified platform where version control and delivery pipelines coexist in one place.

This article explains how GitLab CI/CD works, which components you need to know, and why it has become a popular solution for automating software delivery workflows.

What is GitLab CI/CD?

GitLab CI/CD combines Continuous Integration (CI) and Continuous Delivery (CD) in a single toolset.

CI automates the process of validating code changes. Every time you commit code, GitLab automatically runs tests and builds your project to catch errors early.
CD extends this by automating deployments to staging or production environments.

All pipeline logic is defined in a single YAML file (.gitlab-ci.yml), making CI/CD processes transparent and version-controlled.

Core Concepts and Terminology

To use GitLab CI/CD effectively, you should be familiar with the following building blocks:

• Pipelines: Sequences of steps that define how your code is built, tested, and deployed.
• Jobs: Individual tasks within a pipeline (e.g. unit tests, builds, deployments).
• Components: Reusable building blocks for standardizing CI/CD pipelines.
• Stages: Groups of jobs that run in order (build, test, deploy).
• Runners: Agents that execute the jobs. These can be GitLab-hosted or self-managed.
• .gitlab-ci.yml: The YAML file that defines your CI/CD pipeline, stored in your repository root.
  
  

GitLab CI Components: Composability and Reuse

One of the most impactful features in modern GitLab CI/CD is the introduction of CI Components – a major step forward in standardising and reusing pipeline logic.

What are Components?

Components are reusable, versioned pipeline modules that can be included via the GitLab CI/CD Catalog. Unlike traditional YAML includes or templates, components are fully composable and documented through the GitLab interface.

Benefits for Teams and Enterprises

 Write once, use everywhere – Create reusable logic for security scans, test frameworks, or deployment routines

 Version-controlled & semantic – Each component is tagged and maintained like a regular package

 Less boilerplate – Teams no longer need to duplicate similar logic across .gitlab-ci.yml files

 CI/CD Catalog visibility – Components are discoverable across your organisation via the GitLab interface

Example Usage

This makes pipelines modular, consistent, and faster to maintain, especially across large project portfolios.

More info: Introducing GitLab CI Components

Key Features and Advantages

GitLab CI/CD offers a rich set of capabilities beyond basic automation:

• Integrated experience: CI/CD, Git, code reviews, security scanning – all in one place
  
  
• Powerful pipeline syntax: Parallel jobs, conditional execution, dependencies
  
  
• Security & compliance checks: Built-in static analysis and audit controls
  
  
• Auto DevOps: Auto-detects project type and sets up a full pipeline
  
  
• Highly scalable: From single projects to enterprise-wide workflows with shared runners and reusable components
  
  

How GitLab CI/CD Works

Here’s what a typical GitLab CI/CD workflow looks like:

1. Code push: A developer commits changes to the repository
   
   
2. Pipeline triggered: .gitlab-ci.yml is evaluated and the pipeline starts
   
   
3. Jobs executed: Jobs are picked up by runners based on defined stages
   
   
4. Results & feedback: GitLab shows build status, test reports, artefacts
   
   
5. Deployment: If defined, successful pipelines deploy code automatically
   
   

This automation significantly reduces human error and speeds up delivery cycles.

The CI/CD Workflow at a Glance

Best Practices for Implementation

Keep pipelines fast: Use caching and parallel execution to reduce wait times

Start small: Introduce CI first, then gradually add CD and components

Leverage the component catalog: Avoid reinventing common steps

Use environment variables: Manage secrets and configs securely

Document your logic: Help teams understand and maintain shared pipelines

Conclusion & Next Steps

GitLab CI/CD is more than a pipeline engine – it's a full DevSecOps platform. With the addition of CI Components, organisations can now scale and standardise automation faster than ever.

Whether you're a small team looking to introduce automation or an enterprise aiming to unify delivery pipelines across departments – GitLab CI/CD offers the flexibility and power to support your goals.

Contact us today to learn how we can help implement GitLab CI/CD – including component libraries tailored to your architecture.

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