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 ones 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, considering the organization-level and PR repository rules.

Triggering Mechanism

gitStream automations are triggered by events related to pull requests (PRs). You can specify triggers to fine-tune which events should initiate automations.

Implicit triggers

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

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

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 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

Triggers can be defined globally at the file level or specifically for each automation. Triggers are applied only to the file(s) where they are declared.

triggers section

The triggers section in gitStream gives you precise control over when automations execute. It allows you to define conditions based on pull request events using include and exclude lists to specify branch and repository patterns. These lists determine which branches or repositories trigger or bypass automation but do not affect the events initiating automations.

Additionally, the on keyword defines specific events that trigger automations. It can be added at the file level (under the triggers section) or within individual automations for greater customization. Multiple triggers can be stacked, meaning gitStream will execute the automation for each matching triggering event, allowing flexibility in defining automation behavior

The table below lists supported explicit triggers, categorized into those enabled by default and those that require manual activation.

Explicit triggers are set independently per each automation block and can be configured at the file level, specific to each automation separately or in combination. If 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.

Note on Matching:

• When using a String as the matching type, the values in triggers.include.* and triggers.exclude.* require exact matches. This means that the names of branches or repositories must exactly match the specified string to either trigger or prevent triggering the automation.
• For more precise control, use a regular expression (regex) format: r/REGEX_PATTERN/.

Default Behavior:

• Implicit triggers are the default behavior if the automation doesn't have explicit triggers configured.
• The automation runs for all branches and repositories if neither include nor exclude is specified.

Exclude/Include prioritization

• Exclude overrides the include option. Thus, a repo will be excluded when it matches the include and exclude lists.

  In the following example, the automations in the file will be triggered for all repositories that contain the string feature, except for the repository my_feature

  triggers:
    include:
      repository:
        - r/feature/
    exclude:
      repository:
        - my_feature
  

Examples

Dependabot and Renovate

For example, you can have your normal automations that help developers with their PRs and a separate automation that automates Dependabot or Renovate version bumps. Both automations serve distinctly different purposes: the first helps your developers streamline their PRs, while the other reduces developers' toil by auto-approving version bumps. You will not want to unnecessarily trigger gitStream for Dependabot or Renovate, so you can configure the triggers to exclude the branch where Dependabot or Renovate PRs are created.

In your default automation file, you should exclude the branch where Dependabot or Renovate PRs are created:

manifest:
  version: 1.0

# Disable triggering when the PR is created by bots
triggers:
  exclude:
    branch:
      - r/(Dependabot|dependabot|Renovate|renovate)/

# The default automations for developers below
automations:
  estimated_time_to_review:
    if:
      - true
    run:
      - action: add-label@v1
        args:
          label: "{{ calc.etr }} min review"
  ...

And the other automations file is set to automate Dependabot PRs:

manifest:
  version: 1.0

triggers:
  include:
    branch:
      - r/(Dependabot|dependabot|Renovate|renovate)/

automations:
  bump_minor:
    if:
      - {{ bump == 'minor' }}
      - {{ branch.name | includes(term="dependabot") }}
      - {{ branch.author | includes(term="dependabot") }}
    run:
      - action: approve@v1
      - action: add-comment@v1
        args:
          comment: |
            Dependabot `minor` version bumps are approved automatically.

  bump_patch:
    if:
      - {{ bump == 'patch' }}
      - {{ branch.name | includes(term="dependabot") }}
      - {{ branch.author | includes(term="dependabot") }}
    run:
      - action: approve@v1
      - action: merge@v1
      - action: add-comment@v1
        args:
          comment: |
            Dependabot `patch` version bumps are approved and merged automatically.

bump: {{ pr.description | extractDependabotVersionBump | compareSemver }}

Assign code expert

Assign code expert reviewer when the PR is created and after each commit. Ignore branches with the string "hotfix" in them.

triggers:
  on:
    - pr_created
    - commit
  exclude:
    branch:
      - hotfix

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

Explain code experts

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.

triggers:
  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

Branch regex pattern

Trigger only specific automations branch pattern A, and trigger other automation for all other branches except those that fit the pattern REGEX_PATTERN

# Automation in this file will trigger only for branch pattern REGEX_PATTERN
triggers:
  include:
    branch:
      - r/REGEX_PATTERN/

# Automations in this file will trigger for all branches except pattern REGEX_PATTERN
triggers:
  exclude:
    branch:
      - r/REGEX_PATTERN/