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gitStream Configuration Overview

Continuous Merge automation files have a .cm extension. In a repository, gitStream loads and parse the .cm directory, which can have multiple automation files, each of which is evaluated independently.

You can edit the .cm files and add your own checks and rules. Check out the Automation examples.

Automation rules

There are two types of automation rules: repository level rules and organization level rules.

Repository level rules are set by creating a special .cm directory in the repository root. Automation rules are specified in files in this directory, which can have any name but must end with .cm.

Organization level rules are defined by creating a special repository named cm in the organization or group. In this repository, you can add CM automation files, which will apply to all the repositories that gitStream app is connected.

When organization level rules are defines, repository level automation shall take precedence and override organization automation when having the same identifier.

An automation identifier is a composition of the CM file name and the automation name. For example when safe_changes is defined in then the automation identifier shall be gitstream/safe_changes


You can select (include or exclude) certain repositories per automation file using the triggers.include.repository and triggers.exclude.repository

Repository automation rules

Repository automation rules are set by creating a special .cm directory in your repository root. Automation rules are specified in files in this directory, these files can have any name but must end with .cm. By default, you start with a single automation file .cm/

Every file is parsed independently, and the parsing results are combined and executed.


  1. Automation rules are allowed to have same name in different .cm files
  2. The config section is defined per .cm file (except config.admin)
  3. Any accessory expression defined in each file scope, therefore cannot be reused in another file (but it can be duplicated)

When configured correctly, your repository directory structure should look like that (for GitHub):

Repsository automation rules
├─ .cm/
│  └─ *.cm
├─ .github/
│  └─ workflows/
│     └─ gitstream.yml


The .cm/ is special, as it allows repository-level configuration such as config.admin.

Organization automation rules

Organization automation rules are defined by creating a special repository cm in your organization or group. In this repository, you can add CM automation files, which will apply to all the repositories that gitStream app is connected.

When configured correctly, the cm repository directory structure should look like that (for GitHub):

Repsository automation rules
├─ *.cm
├─ .github/
│  └─ workflows/
│     └─ gitstream.yml

For each PR the following automation rules are applied:

  1. Repository level rules
  2. Organization-level rules, unless with the same identifier as a repository-level automation

When organization level rules are defined, then the CI/CD will be executed on the cm repository on behalf of the PR repository.

Setting up Global Automation rules

By utilizing the following techniques, you can effectively combine and manage global and repository rules to customize the behavior of your automations to fit the specific requirements of your repositories:

  1. Global rules are defined in the configuration management cm repository and are applied to all repositories that are connected to gitStream.
  2. To exclude or run only on specific repositories from a global rule, you can use triggers.include.repository and triggers.exclude.repository in the cm file and add a list of the unwanted or wanted repositories respectfully.
  3. To override a global rule for specific automation in a repository, you can duplicate the rule (both the file and automation name) and place it in the desired repository. The locally defined rule will then take precedence over the global rule for that specific repository.

The .cm automation file


The following sections are used in .cm file to describe the desired automations:


The first section in a file is the manifest.

  version: 1.0

The only field required is version.

Key Required Type Description
manifest Y Map The manifest section root
manifest.version Y String Specify the .cm spec version: 0.1, 1.0

The manifest version field is used to parse the .cm file, in the future if breaking changes are introduced to the parser then older automation will be still supported.


The config section in the .cm file is optional and specifies settings that affect gitStream's operation within a given context.

Key Type Default Scope Description
config Map - per .cm file Root configuration section, applies to the automations defined in the current file.
config.admin.users [String] [] List of admin users, identified by Git provider usernames.
config.ignore_files [String] [] per .cm file Files to exclude from consideration.
config.user_mapping [String: String] [] per .cm file Map Git user details to provider account names.

When specified in the config.admin.users allows adding admin rights, when a PR changes the *.cm files only, if the user is listed in config.admin.users the PR will be then approved by gitStream. For example, setting popeye as admin:

    users: ['popeye']

This configuration is valid only when used in .cm/, when defined in other .cm files this configuration is ignored.

When you add a user to config.admin.users in your organization's cm repository, they are granted administrative privileges to CM changes across every repository in the organization. gitStream evaluates CM rules in the individual repository and your organization's cm repository to determine admin users.


The config.ignore_files supports glob pattern matching that contains a list of files to ignore.

Common usage, since some files such as lock files are intentionally not a required part of a review, they would not want to them to be counted in the estimated review time. In such cases, you can add config.ignore_files to the relevant CM file, for example:

    - 'yarn.lock'
    - 'package-lock.json'
    - 'openapi.json'
    - 'ui/src/**/*Model.d.ts'

Accepts list of key value strings.

For example, when using rankByGitBlame or explainRankByGitBlame Git users are mapped to their matching Git provider accounts based on the Git details. The automatic mapping can sometimes result with the wrong account or fail to find a proper mapping, in these cases you can configure the config.user_mapping. This allows you to map confusing Git user into their specific accounts and dump some irrelevant accounts:

    - 'Popeye Man <>': 'popeye-the-salyor-man' # (1)
    - 'Popeye Man <>': 'popeye-the-salyor-man' # (2)
    - 'olive <>': null # (3)
  1. Map Git user signature to the correct Git provider user name (e.g. GitHub)
  2. Map Git user signature to the correct Git provider user name (e.g. GitHub)
  3. Mapping to null removes this Git user from the suggested results

When using rankByGitBlame to assign reviewers automatically with add-reviewers@v1 then mapping users to null is a way to prevent the automatic mapping in certain cases, like in your example contributors that are not longer part of the team.

On the other hand, when using explainRankByGitBlame with add-comment@v1 it still shows these users details in the PR comment suggestion as this info might be valuable by itself.

- action: add-reviewers@v1
  args: # (1)
    reviewers: {{ repo | rankByGitBlame(gt=25) }}

- action: add-comment@v1
  args: # (2)
    comment: |
      {{ repo | explainRankByGitBlame(gt=25) }}
  1. rankByGitBlame will drop null users
  2. explainRankByGitBlame will NOT drop null users


The triggers is section specifies when automations are executed, supporting include and exclude lists for branch and repository patterns at the file level. The on keyword can also be used within individual automations to define specific events that trigger those automations.

    - pr_created
    - commit
      - hotfix

Read more here: triggers.


The automations section defines the automations and their conditions.

      - {{ }}
      - action: add-label@v1
          label: xsmall

Each automation includes its name, and few fields: if and run.

Key Required Type Description
automations Y Map The automations section root
automations.NAME Y Map User defined name of the automation, can be any string
automations.NAME.if Y Map List of conditions with AND relationship Y Map Actions to run if all conditions are met, invoked one by one

The if field includes the list of conditions. The conditions are checked when a pull request is opened or changed, if all the conditions pass, the automation is executed.

The run field includes the automation to execute. It includes the following fields:

Key Required Type Description
action Y String The action pointer
engine N String The action engine, default is gitstream
args N List The action inputs list

For gitstream engine, the action is specified by: name@version

gitStream supported actions, see actions.

Reusing checks

You can define an accessory section, e.g. checks, that defines common conditions, and reuse.

    small: {{ branch.diff.size < 20 }}
    medium: {{ branch.diff.size >= 20 and branch.diff.size < 100 }}
    large: {{ branch.diff.size >= 100 }}

      - {{ }}
      - action: approve@v1
      # Check that the PR is either small or medium size
      - {{ or }}
      # AND its less than 5 minutes review (estimated)
      - {{ branch | estimatedReviewTime <= 5 }}
      - action: add-label@v1
          label: 'good-size'