Top 50 GitLab CI/CD Interview Question and Answers

07 Oct 2024 - Shyam Mohan

1. What is GitLab CI/CD?

• Answer: GitLab CI/CD is a built-in tool in GitLab for continuous integration (CI) and continuous delivery/deployment (CD). It automates the process of software development, testing, and deployment.

2. What are the key components of GitLab CI/CD?

• Answer: The key components include:
  • .gitlab-ci.yml file: Defines the pipeline configuration.
  • Runners: Execute jobs.
  • Jobs and Stages: Define tasks and group them.
  • Pipelines: Automate workflows from code to deployment.

3. How do you define a pipeline in GitLab CI/CD?

• Answer: A pipeline is defined in the .gitlab-ci.yml file, where you specify stages, jobs, and configuration for each job in a YAML format.

4. What is the .gitlab-ci.yml file?

• Answer: It’s a YAML file placed in the root directory of a GitLab repository that contains the configuration for CI/CD pipelines.

5. Explain GitLab Runners.

• Answer: Runners are processes that execute the scripts defined in GitLab CI/CD jobs. They can be shared or specific to a project.

6. What are the types of GitLab Runners?

• Answer: Runners are classified into:
  • Shared Runners: Used by multiple projects.
  • Specific Runners: Dedicated to a single project.

7. How do you install a GitLab Runner?

• Answer: You can install a GitLab Runner by downloading the runner binary, registering it with your GitLab instance, and setting up the desired configuration.

8. What is a Job in GitLab CI/CD?

• Answer: A job is a task defined in .gitlab-ci.yml that runs independently and can contain various commands to perform specific tasks, like building or testing.

9. What are Stages in GitLab CI/CD?

• Answer: Stages are used to group jobs in a pipeline, allowing jobs in one stage to execute only after jobs in previous stages are complete.

10. How can you define stages in GitLab?

• Answer: Stages are defined at the top level in the .gitlab-ci.yml file under the stages keyword, with each job assigned a stage.

11. What is caching in GitLab CI/CD?

• Answer: Caching stores dependencies or compiled outputs to reduce redundant processing time in future jobs or pipelines.

12. What is an artifact in GitLab CI/CD?

• Answer: Artifacts are the outputs of jobs that are saved and can be used by later stages or downloaded from GitLab.

13. How do you set up a deployment job in GitLab?

• Answer: Set up a deployment job by defining a job with a stage: deploy in the .gitlab-ci.yml and configuring the deployment commands.

14. What is the only and except keyword in GitLab CI/CD?

• Answer: only specifies the branches or tags that the job will run on, while except excludes certain branches or tags.

15. How does the variables keyword work in GitLab CI/CD?

• Answer: variables define environment variables that jobs can use, either globally or within specific jobs.

16. How can you define job dependencies in GitLab?

• Answer: Use the dependencies keyword to define which jobs a job depends on, allowing access to their artifacts.

17. What is a trigger in GitLab CI/CD?

• Answer: Triggers allow you to start a pipeline from an external event, API call, or another project.

18. What is before_script and after_script in GitLab CI/CD?

• Answer: before_script runs commands before each job, while after_script runs commands after each job.

19. Explain GitLab environment variables.

• Answer: GitLab environment variables allow storage of credentials, secrets, or other dynamic configuration settings within the CI/CD pipeline.

20. How do you run a job manually in GitLab CI/CD?

• Answer: Use the when: manual attribute within a job definition, which requires manual intervention to trigger.

21. What is a manual job in GitLab CI/CD?

• Answer: A manual job is set to when: manual, meaning it will not automatically run and requires user initiation.

22. What is GitLab CI/CD’s auto-cancel feature?

• Answer: The auto-cancel feature automatically cancels redundant pipelines for a branch if a new commit is pushed.

23. Explain only: changes in GitLab CI/CD.

• Answer: This runs jobs only when specified files or directories change.

24. What is a multi-project pipeline?

• Answer: Multi-project pipelines allow triggering pipelines across different GitLab projects, enhancing cross-project CI/CD workflows.

25. How can you pass artifacts between stages?

• Answer: Artifacts are defined in one job and retrieved by specifying dependencies in subsequent jobs.

26. How do you handle secret management in GitLab CI/CD?

• Answer: Use GitLab’s environment variables and vault integrations to securely store and retrieve secrets.

27. What is GitLab CI/CD’s ‘needs’ keyword?

• Answer: needs allows jobs to run concurrently even if they are in different stages.

28. What is the purpose of the script keyword?

• Answer: It defines the list of commands that will execute within a job.

29. How does GitLab CI/CD handle retries for failed jobs?

• Answer: GitLab allows you to set retry options to automatically retry failed jobs.

30. What are extends in GitLab CI/CD?

• Answer: extends allows jobs to inherit configurations from another job or job template.

31. What is the purpose of include in GitLab CI/CD?

• Answer: include allows you to import external .yml configurations into the main .gitlab-ci.yml.

32. How do you set up pipeline notifications in GitLab?

• Answer: Configure notifications by setting up integrations or using the notification_email and Slack webhook options.

33. How does GitLab CI/CD support Kubernetes deployments?

• Answer: GitLab integrates with Kubernetes clusters, allowing CI/CD pipelines to deploy applications directly to Kubernetes.

34. How do you skip a pipeline in GitLab?

• Answer: Add [skip ci] to the commit message to skip triggering a pipeline.

35. How can you limit job concurrency in GitLab CI/CD?

• Answer: Use resource_group to restrict concurrency of jobs within a resource group.

36. What is a parent-child pipeline in GitLab?

• Answer: Parent-child pipelines split complex pipelines into separate child pipelines triggered by a parent.

37. What are GitLab CI/CD templates?

• Answer: Templates are reusable YAML configurations provided by GitLab for common CI/CD tasks.

38. How do you debug failed jobs in GitLab CI/CD?

• Answer: Enable debugging in jobs using DEBUG flags, check job logs, and use retry or SSH to troubleshoot.

39. What is a dynamic environment in GitLab?

• Answer: Dynamic environments are temporary environments created for specific branches or merges, used for testing.

40. How do you manage conditional job execution?

• Answer: Use rules like only, except, rules, and variables to conditionally execute jobs based on branch, tag, or pipeline type.

41. What is GitLab CI/CD’s Vault integration?

• Answer: GitLab integrates with HashiCorp Vault to manage and securely inject secrets into CI/CD jobs.

42. How do you handle failed job notifications?

• Answer: Configure project notifications, use Slack/webhook integrations, or define specific notification settings for failed jobs.

43. What is allow_failure in GitLab CI/CD?

• Answer: allow_failure lets a job fail without impacting the overall pipeline status.

44. What are protected variables in GitLab?

• Answer: Protected variables are available only on protected branches or tags, enhancing security for sensitive information.

45. What is a release job in GitLab CI/CD?

• Answer: A release job is a job that creates and publishes a release package, often used in production deployments.

46. How do you roll back a deployment in GitLab CI/CD?

• Answer: Rollback can be automated by defining a separate rollback job or using GitLab’s environment rollback features.

47. How do you handle database migrations in GitLab CI/CD?

• Answer: Use a dedicated migration job or script that executes during deployment to apply changes to the database schema.

48. How can you secure your CI/CD pipeline in GitLab?

• Answer: Secure CI/CD by using protected branches, environment variables, Vault integration, and limiting runner access.

49. What is the purpose of GitLab CI/CD’s CI_LINT API?

• Answer: The CI_LINT API checks the syntax and validity of .gitlab-ci.yml files, helpful for testing configurations.

50. How do you automate GitLab CI/CD for monorepo projects?

• Answer: Use only: changes for specific job triggers, define multiple pipelines in .gitlab-ci.yml, or split jobs based on subdirectories.