{"id":49473,"date":"2025-05-26T19:05:08","date_gmt":"2025-05-26T19:05:08","guid":{"rendered":"https:\/\/www.devopsschool.com\/blog\/?p=49473"},"modified":"2026-02-21T07:28:48","modified_gmt":"2026-02-21T07:28:48","slug":"gitlab-ci-cd-execution-hierarchy","status":"publish","type":"post","link":"https:\/\/www.devopsschool.com\/blog\/gitlab-ci-cd-execution-hierarchy\/","title":{"rendered":"GitLab CI\/CD Execution Hierarchy"},"content":{"rendered":"\n

Understanding the hierarchy, precedence, sequencing, and parallelism<\/strong> in GitLab CI\/CD pipelines<\/strong> is crucial to mastering how your jobs run, how to optimize them, and how GitLab decides what to execute and when.<\/p>\n\n\n\n

Here\u2019s a complete and up-to-date (GitLab 18.0, May 2026)<\/strong> breakdown of the GitLab pipeline execution model<\/strong>:<\/p>\n\n\n\n

\n\n\n\n

\ud83e\uddf1 1. \ud83d\udd04 GitLab CI\/CD Execution Hierarchy<\/h2>\n\n\n\n

\u27a4 Pipeline<\/strong> (Top-Level Entity)<\/em><\/h3>\n\n\n\n

A single run of your .gitlab-ci.yml<\/code> file. Triggered by:<\/p>\n\n\n\n

    \n
  • Push\/merge\/tag<\/li>\n\n\n\n
  • Schedule<\/li>\n\n\n\n
  • Manual trigger<\/li>\n\n\n\n
  • API call<\/li>\n<\/ul>\n\n\n\n

    \u27a4 Stages<\/strong> (Sequential Execution Layer)<\/em><\/h3>\n\n\n\n

    Defines the order<\/strong> of execution \u2014 each stage completes fully before the next begins.<\/p>\n\n\n

    stages:\n  - lint\n  - test\n  - build\n  - deploy\n<\/code><\/span><\/pre>\n\n\n
    \u27a4 Jobs<\/strong> (Inside Each Stage)<\/em><\/h3>\n\n\n\n
    All jobs within a stage run in parallel<\/strong>, provided runners are available.<\/p>\n\n\n
    lint:\n  stage: lint\n  script: npm run lint\n\nunit_test:\n  stage: test\n  script: npm test\n<\/code><\/span><\/pre>\n\n\n
    \u27a4 Steps inside a Job<\/strong><\/h3>\n\n\n\n
    Each job\u2019s script:<\/code> section contains commands that run sequentially<\/strong> inside the job’s shell or container.<\/p>\n\n\n\n
    \n\n\n\n
    \ud83d\udd03 2. Pipeline Execution Flow<\/h2>\n\n\n
    Pipeline\n \u251c\u2500\u2500 Stage 1: lint\n \u2502    \u251c\u2500\u2500 job: lint_a  (parallel)\n \u2502    \u2514\u2500\u2500 job: lint_b  (parallel)\n \u251c\u2500\u2500 Stage 2: test\n \u2502    \u251c\u2500\u2500 job: unit_tests\n \u2502    \u2514\u2500\u2500 job: integration_tests\n \u251c\u2500\u2500 Stage 3: build\n \u2502    \u2514\u2500\u2500 docker_build\n \u2514\u2500\u2500 Stage 4: deploy\n      \u251c\u2500\u2500 job: staging_deploy\n      \u2514\u2500\u2500 job: prod_deploy (manual)\n<\/code><\/span><\/pre>\n\n\n
    \n\n\n\n
    \u23f1\ufe0f 3. Job Precedence & Order of Execution<\/h2>\n\n\n\n
    \u2705 Within a Stage<\/strong>:<\/h3>\n\n\n\n
      \n
    • Jobs run in parallel<\/strong><\/li>\n\n\n\n
    • No strict order unless using needs:<\/code> (see below)<\/li>\n<\/ul>\n\n\n\n
      \u2705 Between Stages<\/strong>:<\/h3>\n\n\n\n
        \n
      • Sequential<\/strong>: Stage 2 starts only if<\/strong> all Stage 1 jobs succeed<\/strong><\/li>\n<\/ul>\n\n\n\n
        \n\n\n\n
        \u26a1 4. How to Run Jobs in Parallel or Control Order<\/h2>\n\n\n\n
        \ud83d\udd39 Parallel Jobs<\/strong><\/h3>\n\n\n\n
        Jobs in the same stage naturally run in parallel. Example:<\/p>\n\n\n
        test_backend:\n  stage: test\n  script: run backend tests\n\ntest_frontend:\n  stage: test\n  script: run frontend tests\n<\/code><\/span><\/pre>\n\n\n
        \ud83d\udd39 Needs: (Run jobs out-of-order \/ faster)<\/strong><\/h3>\n\n\n\n
        Allows stage-skipping<\/strong> and job-level dependency. Ideal for reducing pipeline time.<\/p>\n\n\n
        unit_test:\n  stage: test\n  script: run tests\n\ndocker_build:\n  stage: build\n  script: build docker\n  needs: [unit_test]   # Doesn't wait for whole test stage<\/span>\n<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
        \ud83d\udd39 Dependencies<\/strong> (Job artifact consumption, older method)<\/h3>\n\n\n\n
        Specify jobs that must complete before current job can use their artifacts<\/strong>.<\/p>\n\n\n
        deploy<\/span>:\n  stage<\/span>: deploy<\/span>\n  dependencies<\/span>: [build]<\/span>\n<\/code><\/span>Code language:<\/span> CSS<\/span> (<\/span>css<\/span>)<\/span><\/small><\/pre>\n\n\n
        \n
        \ud83d\udd01 Use needs:<\/code> for parallel dependency-based optimization
        \ud83d\udce6 Use dependencies:<\/code> to pass artifacts<\/p>\n<\/blockquote>\n\n\n\n
        \n\n\n\n
        \ud83e\uddea 5. Conditional Execution (Job-Level Control)<\/h2>\n\n\n\n
        \ud83d\udd38 Rules<\/strong><\/h3>\n\n\n\n
        Recommended way to control job execution with complex conditions.<\/p>\n\n\n
        job_a:\n  rules:\n    - if<\/span>: '$CI_COMMIT_BRANCH == \"main\"'<\/span>\n<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
        \ud83d\udd38 only\/except<\/strong> (Deprecated in favor of rules<\/code>)<\/h3>\n\n\n
        job_b:\n  only:\n    - branches\n    - tags\n<\/code><\/span><\/pre>\n\n\n
        \n\n\n\n
        \ud83c\udfaf 6. Extended Structures<\/h2>\n\n\n\n
        Structure<\/th>Purpose<\/th>Notes<\/th><\/tr><\/thead>
        Parent-Child Pipelines<\/strong><\/td>Modularize pipelines (include from other .yml<\/code>)<\/td>Ideal for monorepos<\/td><\/tr>
        Multi-project Pipelines<\/strong><\/td>Trigger another project\u2019s pipeline<\/td>Good for microservice chaining<\/td><\/tr>
        Includes<\/strong><\/td>Reuse YAML templates<\/td>From same repo or remote<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
        \n\n\n\n
        \ud83d\udccb 7. Visual: GitLab CI\/CD Execution Hierarchy<\/h2>\n\n\n
        Pipeline\n\u251c\u2500\u2500 Stages (sequential)\n\u2502   \u251c\u2500\u2500 Jobs (parallel unless controlled)\n\u2502   \u2502   \u251c\u2500\u2500 Scripts (sequential commands)\n\u2502   \u2502   \u2514\u2500\u2500 Artifacts\/Needs\/Dependencies\n\u251c\u2500\u2500 Includes \/ Child Pipelines (optional)\n\u2514\u2500\u2500 Triggered Pipelines (optional)\n<\/code><\/span><\/pre>\n\n\n
        \n\n\n\n
        \u2705 Summary: Controlling Flow & Parallelism<\/h2>\n\n\n\n
        Control Mechanism<\/th>Used For<\/th><\/tr><\/thead>
        stages:<\/code><\/td>Define sequential job groupings<\/td><\/tr>
        needs:<\/code><\/td>Define parallel dependencies<\/td><\/tr>
        rules:<\/code><\/td>Fine-grained control of job triggers<\/td><\/tr>
        when:<\/code><\/td>Delay, manual, or conditional jobs<\/td><\/tr>
        only\/except<\/code><\/td>Basic conditions (legacy)<\/td><\/tr>
        dependencies:<\/code><\/td>Artifact-based job dependencies<\/td><\/tr>
        trigger:<\/code><\/td>Trigger child or multi-project pipelines<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
        \n\n\n\n
        <\/p>\n","protected":false},"excerpt":{"rendered":"
        Understanding the hierarchy, precedence, sequencing, and parallelism in GitLab CI\/CD pipelines is crucial to mastering how your jobs run, how to optimize them, and how GitLab decides what to execute… <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_joinchat":[],"footnotes":""},"categories":[2],"tags":[],"class_list":["post-49473","post","type-post","status-publish","format-standard","hentry","category-uncategorised"],"_links":{"self":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/49473","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/comments?post=49473"}],"version-history":[{"count":2,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/49473\/revisions"}],"predecessor-version":[{"id":58986,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/49473\/revisions\/58986"}],"wp:attachment":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/media?parent=49473"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/categories?post=49473"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/tags?post=49473"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}