Trigger one pipeline after another

Azure DevOps Services | Azure DevOps Server 2020

Large products have several components that are dependent on each other. These components are often independently built. When an upstream component (a library, for example) changes, the downstream dependencies have to be rebuilt and revalidated.

In situations like these, add a pipeline trigger to run your pipeline upon the successful completion of the triggering pipeline.

Note

Previously, you may have navigated to the classic editor for your YAML pipeline and configured build completion triggers in the UI. While that model still works, it is no longer recommended. The recommended approach is to specify pipeline triggers directly within the YAML file. Build completion triggers as defined in the classic editor have various drawbacks, which have now been addressed in pipeline triggers. For instance, there is no way to trigger a pipeline on the same branch as that of the triggering pipeline using build completion triggers.

Configure pipeline resource triggers

To trigger a pipeline upon the completion of another pipeline, configure a pipeline resource trigger.

The following example configures a pipeline resource trigger so that a pipeline named app-ci runs after any run of the security-lib-ci pipeline completes.

This example has the following two pipelines.

  • security-lib-ci - This pipeline runs first.

    # security-lib-ci YAML pipeline
    steps:
    - bash: echo "The security-lib-ci pipeline runs first"
    
  • app-ci - This pipeline has a pipeline resource trigger that configures the app-ci pipeline to run automatically every time a run of the security-lib-ci pipeline completes.

    # app-ci YAML pipeline
    # We are setting up a pipeline resource that references the security-lib-ci
    # pipeline and setting up a pipeline completion trigger so that our app-ci
    # pipeline runs when a run of the security-lib-ci pipeline completes
    resources:
      pipelines:
      - pipeline: securitylib # Name of the pipeline resource.
        source: security-lib-ci # The name of the pipeline referenced by this pipeline resource.
        project: FabrikamProject # Required only if the source pipeline is in another project
        trigger: true # Run app-ci pipeline when any run of security-lib-ci completes
    
    steps:
    - bash: echo "app-ci runs after security-lib-ci completes"
    
  • - pipeline: securitylib specifies the name of the pipeline resource. Use the label defined here when referring to the pipeline resource from other parts of the pipeline, such as when using pipeline resource variables or downloading artifacts.
  • source: security-lib-ci specifies the name of the pipeline referenced by this pipeline resource. You can retrieve a pipeline's name from the Azure DevOps portal in several places, such as the Pipelines landing page. By default, pipelines are named after the repository that contains the pipeline. To update a pipeline's name, see Pipeline settings.
  • project: FabrikamProject - If the triggering pipeline is in another Azure DevOps project, you must specify the project name. This property is optional if both the source pipeline and the triggered pipeline are in the same project. If you specify this value and your pipeline doesn't trigger, see the note at the end of this section.
  • trigger: true - Use this syntax to trigger the pipeline when any version of the source pipeline completes. See the following sections in this article to learn how to filter which versions of the source pipeline completing will trigger a run. When filters are specified, the source pipeline run must match all of the filters to trigger a run.

If the triggering pipeline and the triggered pipeline use the same repository, both pipelines will run using the same commit when one triggers the other. This is helpful if your first pipeline builds the code and the second pipeline tests it. However, if the two pipelines use different repositories, the triggered pipeline will use the version of the code in the branch specified by the Default branch for manual and scheduled builds setting, as described in Branch considerations for pipeline completion triggers.

Note

In some scenarios, the default branch for manual builds and scheduled builds doesn't include a refs/heads prefix. For example, the default branch might be set to main instead of to refs/heads/main. In this scenario, a trigger from a different project doesn't work. If you encounter issues when you set project to a value other than the target pipeline's, you can update the default branch to include refs/heads by changing its value to a different branch, and then by changing it back to the default branch you want to use.

Branch filters

You can optionally specify the branches to include or exclude when configuring the trigger. If you specify branch filters, a new pipeline is triggered whenever a source pipeline run is successfully completed that matches the branch filters. In the following example, the app-ci pipeline runs if the security-lib-ci completes on any releases/* branch, except for releases/old*.

# app-ci YAML pipeline
resources:
  pipelines:
  - pipeline: securitylib
    source: security-lib-ci
    trigger: 
      branches:
        include: 
        - releases/*
        exclude:
        - releases/old*

Note

If your branch filters aren't working, try using the prefix refs/heads/. For example, use refs/heads/releases/old*instead of releases/old*.

Tag filters

The tags property of the trigger filters which pipeline completion events can trigger your pipeline. If the triggering pipeline matches all of the tags in the tags list, the pipeline runs.

resources:
  pipelines:
  - pipeline: MyCIAlias
    source: Farbrikam-CI
    trigger:
      tags:        # This filter is used for triggering the pipeline run
      - Production # Tags are AND'ed
      - Signed

Note

The pipeline resource also has a tags property. The tags property of the pipeline resource is used to determine which pipeline run to retrieve artifacts from, when the pipeline is triggered manually or by a scheduled trigger. For more information, see Resources: pipelines and Evaluation of artifact version.

Stage filters

You can trigger your pipeline when one or more stages of the triggering pipeline complete by using the stages filter. If you provide multiple stages, the triggered pipeline runs when all of the listed stages complete.

resources:
  pipelines:
  - pipeline: MyCIAlias  
    source: Farbrikam-CI  
    trigger:    
      stages:         # This stage filter is used when evaluating conditions for 
      - PreProduction # triggering your pipeline. On successful completion of all the stages
      - Production    # provided, your pipeline will be triggered. 

Branch considerations

Pipeline completion triggers use the Default branch for manual and scheduled builds setting to determine which branch's version of a YAML pipeline's branch filters to evaluate when determining whether to run a pipeline as the result of another pipeline completing. By default this setting points to the default branch of the repository.

When a pipeline completes, the Azure DevOps runtime evaluates the pipeline resource trigger branch filters of any pipelines with pipeline completion triggers that reference the completed pipeline. A pipeline can have multiple versions in different branches, so the runtime evaluates the branch filters in the pipeline version in the branch specified by the Default branch for manual and scheduled builds setting. If there is a match, the pipeline runs, but the version of the pipeline that runs may be in a different branch depending on whether the triggered pipeline is in the same repository as the completed pipeline.

  • If the two pipelines are in different repositories, the triggered pipeline version in the branch specified by Default branch for manual and scheduled builds is run.
  • If the two pipelines are in the same repository, the triggered pipeline version in the same branch as the triggering pipeline is run, even if that branch is different than the Default branch for manual and scheduled builds, and even if that version does not have branch filters that match the completed pipeline's branch. This is because the branch filters from the Default branch for manual and scheduled builds branch are used to determine if the pipeline should run, and not the branch filters in the version that is in the completed pipeline branch.

If your pipeline completion triggers don't seem to be firing, check the value of the Default branch for manual and scheduled builds setting for the triggered pipeline. The branch filters in that branch's version of the pipeline are used to determine whether the pipeline completion trigger initiates a run of the pipeline. By default, Default branch for manual and scheduled builds is set to the default branch of the repository, but you can change it after the pipeline is created.

A typical scenario in which the pipeline completion trigger doesn't fire is when a new branch is created, the pipeline completion trigger branch filters are modified to include this new branch, but when the first pipeline completes on a branch that matches the new branch filters, the second pipeline doesn't trigger. This happens if the branch filters in the pipeline version in the Default branch for manual and scheduled builds branch don't match the new branch. To resolve this trigger issue you have the following two options.

  • Update the branch filters in the pipeline in the Default branch for manual and scheduled builds branch so that they match the new branch.
  • Update the Default branch for manual and scheduled builds setting to a branch that has a version of the pipeline with the branch filters that match the new branch.

Combining trigger types

When you specify both CI triggers and pipeline triggers in your pipeline, you can expect new runs to be started every time a push is made that matches the filters the CI trigger, and a run of the source pipeline is completed that matches the filters of the pipeline completion trigger.

For example, consider two pipelines named A and B that are in the same repository, both have CI triggers, and B has a pipeline completion trigger configured for the completion of pipeline A. If you make a push to the repository:

  • A new run of A is started, based on its CI trigger.
  • At the same time, a new run of B is started, based on its CI trigger. This run consumes the artifacts from a previous run of pipeline A.
  • When A completes, it triggers another run of B, based on the pipeline completion trigger in B.

To prevent triggering two runs of B in this example, you must remove its CI trigger or pipeline trigger.