GitLab DAG & Parallelism Skill

Use this skill to design, generate, review, and fix GitLab CI/CD pipeline configurations that leverage DAG (needs:) and parallelism (parallel:, parallel:matrix).

Core Concepts

Standard Stage Order vs DAG

Without DAG: Jobs execute strictly stage-by-stage. All jobs in stage N must complete before stage N+1 starts — even if only one job in a stage is the actual prerequisite.

With DAG (needs:): Jobs start as soon as their specific dependencies finish, skipping the stage-order wait. This can dramatically reduce total pipeline time.

# Standard (slow): test waits for ALL build jobs to finish
stages: [build, test, deploy]