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GitLab CI/CD Associate study materials
GitLab CI/CD Associate study resources

GitLab CI/CD Associate: Pipeline Configuration and CI/CD YAML Fundamentals

GitLab CI/CD Associate · Work through your exam, one topic at a time.

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Pipeline Configuration and CI/CD YAML Fundamentals

This domain covers how .gitlab-ci.yml is parsed and composed: which keys are global, which are jobs, how defaults propagate, and how include, extends, and !reference assemble a pipeline. The exam tests whether you can predict the effective configuration of a job after merging, not just recognise keywords.

Structure and reserved keywords

GitLab reads .gitlab-ci.yml from the repository root (overridable with CI_CONFIG_PATH). Top-level keys divide into global keywords (stages, variables, default, include, workflow, image, services, cache, before_script, after_script) and job definitions. Reserved keywords cannot be job names - a job called image or variables makes the file invalid. Job names starting with a dot are hidden templates: parsed, but never added to a pipeline.

stages defaults to build, test, deploy. A job with no stage is placed in test; a job naming an undeclared stage fails pipeline creation. Every job needs script (or trigger). default: centralises image, services, cache, before_script, after_script, tags, retry, timeout, interruptible, and artifacts; a job that declares the key replaces the default rather than merging with it.

Composition

  • include pulls in local, remote, template, component, or other-project files; the result is one merged document. Keep chains shallow - there is a hard cap on the number of includes.
  • extends deep-merges hash keys but replaces arrays, and supports up to eleven levels of inheritance.
  • !reference [job, key] splices one specific value or list item from another job - the way to reuse an array without duplicating it.
  • YAML anchors work within a single file only; do not rely on an anchor defined in one included file being visible in another. Prefer extends or !reference.

Worked example

.defaults:
  image: alpine:3.19
  before_script:
    - echo shared-setup
test:
  extends: .defaults
  before_script:
    - echo job-setup
  script: make test

test inherits image: alpine:3.19, but its own before_script replaces the inherited array, so only echo job-setup runs. To keep both, write before_script: [!reference [.defaults, before_script], - echo job-setup].

Traps

  • Indenting with tabs - YAML rejects them and the pipeline fails before any job starts.
  • Assuming extends concatenates lists such as script or tags.
  • Putting job-only keywords (script, stage, rules) inside default:, where they are unsupported.
  • Shadowing a reserved keyword with a job name.