CI/CD process overview

Get started with GitLab CI/CD

Use this document to get started with GitLab continuous integration.

Before you start, make sure you have:

A project in GitLab that you would like to use CI/CD for.
The Maintainer or Owner role for the project.

If you are migrating from another CI/CD tool, view this documentation:

Watch First time GitLab & CI/CD. This includes a quick introduction to GitLab, the first steps with CI/CD, building a Go project, running tests, using the CI/CD pipeline editor, detecting secrets and security vulnerabilities and offers more exercises for async practice.
Watch Intro to GitLab CI. This workshop uses the Web IDE to quickly get going with building source code using CI/CD, and run unit tests.

CI/CD process overview

To use GitLab CI/CD:

Ensure you have runners available to run your jobs. If you don’t have a runner, install GitLab Runner and register a runner for your instance, project, or group.
Create a .gitlab-ci.yml file at the root of your repository. This file is where you define your CI/CD jobs.

When you commit the file to your repository, the runner runs your jobs. The job results are displayed in a pipeline.

Ensure you have runners available

In GitLab, runners are agents that run your CI/CD jobs.

You might already have runners available for your project, including shared runners, which are available to all projects in your GitLab instance.

To view available runners:

Go to Settings > CI/CD and expand Runners.

As long as you have at least one runner that’s active, with a green circle next to it, you have a runner available to process your jobs.

If no runners are listed on the Runners page in the UI, you or an administrator must install GitLab Runner and register at least one runner.

If you are testing CI/CD, you can install GitLab Runner and register runners on your local machine. When your CI/CD jobs run, they run on your local machine.

Create a `.gitlab-ci.yml` file

The .gitlab-ci.yml file is a YAML file where you configure specific instructions for GitLab CI/CD.

In this file, you define:

The structure and order of jobs that the runner should execute.
The decisions the runner should make when specific conditions are encountered.

For example, you might want to run a suite of tests when you commit to any branch except the default branch. When you commit to the default branch, you want to run the same suite, but also publish your application.

All of this is defined in the .gitlab-ci.yml file.

To create a .gitlab-ci.yml file:

On the left sidebar, select Project information > Details.
Above the file list, select the branch you want to commit to, click the plus icon, then select New file:

For the Filename, type .gitlab-ci.yml and in the larger window, paste this sample code:

build-job:
  stage: build
  script:
    - echo "Hello, $GITLAB_USER_LOGIN!"

test-job1:
  stage: test
  script:
    - echo "This job tests something"

test-job2:
  stage: test
  script:
    - echo "This job tests something, but takes more time than test-job1."
    - echo "After the echo commands complete, it runs the sleep command for 20 seconds"
    - echo "which simulates a test that runs 20 seconds longer than test-job1"
    - sleep 20

deploy-prod:
  stage: deploy
  script:
    - echo "This job deploys something from the $CI_COMMIT_BRANCH branch."

$GITLAB_USER_LOGIN and $CI_COMMIT_BRANCH are predefined variables that populate when the job runs.

Click Commit changes.

The pipeline starts when the commit is committed.

`.gitlab-ci.yml` tips

If you want the runner to use a Docker container to run the jobs, edit the .gitlab-ci.yml file to include an image name:
```
default:
  image: ruby:2.7.2
```
This command tells the runner to use a Ruby image from Docker Hub and to run the jobs in a container that’s generated from the image.
This process is different than building an application as a Docker container. Your application does not need to be built as a Docker container to run CI/CD jobs in Docker containers.
To validate your .gitlab-ci.yml file, use the CI Lint tool, which is available in every project.
You can also use CI/CD configuration visualization to view a graphical representation of your .gitlab-ci.yml file.
For the complete .gitlab-ci.yml syntax, see the .gitlab-ci.yml reference topic.