Job execution flow

The job execution flow describes how GitLab Runner processes CI/CD jobs from start to finish.

GitLab Runner executes CI/CD jobs after it receives a job, retrieves secrets from a vault (if configured), and prepares the executor. Every CI/CD job executes as a series of sequential steps, with each step running in a separate shell context. The runner:

1. Prepares the source code for the job:

   • Exports variables to the shell context
   • Runs pre_get_sources_script if it’s defined in the configuration
   • Executes git fetch and other source handling commands, unless the none strategy is configured
   • Runs commands to update submodules if they exist
   • Runs post_get_sources_script if it’s defined in the configuration

2. Downloads cached files if cache is configured and the previous step succeeded:

   • Exports variables to the shell context
   • Executes commands to download cached files from previous job runs

3. Downloads artifacts from previous jobs if artifact downloading is configured and the previous step succeeded:

   • Exports variables to the shell context
   • Executes commands to download artifact files from previous jobs

4. Executes the main job scripts if the previous step succeeded:

   • Exports variables to the shell context
   • Runs pre_build_script if it’s defined in the configuration
   • Executes the before_script commands if they’re defined
   • Executes the main script commands
   • Runs post_build_script if it’s defined in the configuration

5. Executes after_script commands if they’re defined, regardless of whether previous steps failed:

   • Exports variables to a new shell context
   • Executes the after_script commands
   • Failure of these commands doesn’t influence the overall job status

6. Uploads files to cache if cache uploading is configured, regardless of whether previous steps failed:

   • Exports variables to the shell context
   • Executes commands to upload specified files to cache storage
   • Failure of this step may influence the overall job status

7. Uploads artifacts if artifact uploading is configured, regardless of whether previous steps failed:

   • Exports variables to the shell context
   • Executes commands to upload specified files as job artifacts
   • Failure of this step may influence the overall job status

8. Uploads referee data if referee uploading is configured, regardless of whether previous steps failed:

   • Exports variables to the shell context
   • Executes commands to upload referee information
   • Failure of these commands doesn’t influence the overall job status

9. Performs cleanup operations if they’re configured, regardless of whether previous steps failed:

   • Exports variables to the shell context
   • Executes commands to delete file-based variables from the working directory
   • Failure of these commands doesn’t influence the overall job

%%{init: { "fontFamily": "GitLab Sans" }}%%
flowchart TD
    accTitle: GitLab CI/CD Job Execution Flow
    accDescr: Shows the complete 9-step job execution sequence from source preparation through cleanup operations.

    Start([Job Starts]) --> Source[1. Source preparation<br/><small>Export variables, runs <code>pre_get_sources_script</code>,</small><br/><small><code>git fetch</code>, submodules, <code>post_get_sources_script</code>.</small>]

    Source --> Cache[2. Download cache<br/><small>If configured and previous step succeeds.</small>]

    Cache --> Artifacts[3. Download artifacts<br/><small>If configured and previous step succeeds.</small>]

    Artifacts --> MainExec[4. Main execution<br/><small>Export variables, <code>pre_build_script</code>,</small><br/><small><code>before_script</code>, <code>script</code>, <code>post_build_script</code>.</small>]

    MainExec --> AfterScript[5. <code>after_script</code><br/><small>Always runs if defined.</small><br/><small>Files created here are included.</small>]

    AfterScript --> Critical[⚠️ CRITICAL: <code>after_script</code> runs BEFORE upload stages.]

    Critical --> UploadCache[6. Upload cache<br/><small>Always runs if configured.</small><br/><small>Failure may affect job status.</small>]

    Critical --> UploadArtifacts[7. Upload artifacts<br/><small>Always runs if configured.</small><br/><small>Failure may affect job status.</small>]

    UploadCache --> UploadReferees[8. Upload referees<br/><small>Always runs if configured.</small><br/><small>Failure doesn't affect job status.</small>]

    UploadArtifacts --> UploadReferees

    UploadReferees --> Cleanup[9. Cleanup operations<br/><small>Always runs if configured.</small><br/><small>Delete file-based variables.</small>]

    Cleanup --> End([Job Complete])

Shell context isolation

Each shell context is isolated by design. The only connection between contexts is the shared working directory file system.

• Manual variable exports (like export my_variable=$(date)) in one context are not available in other contexts
• Each script runs with set -eo pipefail (for Unix shells) to fail early on the first error
• The outcome of each step influences whether subsequent steps execute and affects overall job status