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Execution Model

gitStream is triggered on new pull requests (PRs) for repositories that have gitStream installed. Upon triggering, gitStream collects context variables and evaluates the automation rules to determine which automation rules are relevant.

Organization level rules and repository rules

When a central cm repository is set with the CI/CD runner, the events for PRs from all installed repositories shall be evaluated in the cm repository pipeline, taking into account the organization level rules and the PR repository rules.

Triggering events

Implicit triggers

By default, gitStream evaluates any new commit that is pushed to the PR, triggering automation evaluation.

Additionally, if any of the automation rules reference the pr context, gitStream shall trigger and will initiate automation rules evaluation even where there are changes to the PR title, descriptions, labels or comments.

This allows for greater flexibility in the automation process, ensuring that the relevant automation rules are evaluated and triggered when necessary. The execution model ensures that the automation process is streamlined, efficient, and effective.

Explicit triggers

gitstream supports an explicit triggering mechanism. When using explicit triggers, the automations will run only according to the defined triggers, which means the Implicit triggers will not work. Automations triggered by explicit triggers will also be invoked on draft PRs

Explicit triggers syntax

Use explicit triggers to enhance the control and customization of automations in gitStream, allowing users to define precisely when and how automations should be triggered based on various events and actions within pull requests.

Add the on keyword to the file and/or to a specific automation to define explicit triggers. gitStream supports the following explicit triggers:

Trigger Description Default
comment_added Trigger on each added comment off
commit Trigger on each commit after the creation of the PR on
label_added Trigger on each added label on
label_removed Trigger on removed label on
merge Trigger when merging the PR off
pr_created Trigger when the PR is created on

Explicit triggers are set per each automation block independently and can be configured at the file level, specific to each automation separately or a combination of the two. In case triggers are listed at the file level and specific automation, the automation will be triggered according to both triggers. If an automation block does not have explicit triggers configured, it will be triggered according to the default (implicit) triggers.

Examples

  • assign code expert reviewer when the PR is created and after each commit

    on:
      - pr_created
      - commit
    
    automations:
      assign_code_experts:
        if:
          - true
        run:
          - action: add-reviewers@v1
            args:
              reviewers: {{ repo | codeExperts(gt=10) }}
    

  • Explain code experts only if the label “suggest-reviewer” exists. The automation will be triggered after each commit and after each label addition. If the label “suggest-reviewer” exists, it will trigger the explain-code-experts automation

    on:
      - commit
    automations:
      explain_code_experts:
        on:
          - label_added
        if:
          - {{ pr.labels | match(term='suggest-reviewer') | some }}
        run:
          - action: explain-code-experts@v1
            args:
              gt: 10