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Monocle is designed for development teams to provide:

  • analytics on project changes
  • boards to display changes by criteria

It helps teams and individual to better organize daily duties and to detect anomalies in the way changes are produced and reviewed.

Monocle supports GitHub, GitLab and Gerrit.

Explore the website and blog: website

Try on the demo instance:

Chat with us in the project Matrix room:

Screenshots of Monocle from the demo instance

The activity view:

The developer board:

The peers strength view:


The process below describes how to index changes from GitHub repositories and then how to start the web UI to browse metrics.

The deployment is based on Docker via a docker-compose definition.

Clone and create the needed directories

$ git clone
$ cd monocle
$ git submodule update --init --recursive
$ echo CRAWLERS_API_KEY=$(uuidgen) > .secrets
$ ln -s docker-compose.yml.img docker-compose.yml

By default docker-compose will fetch the latest published container images. Indeed, we produce Docker container images for the master version of Monocle. If running master does not fit your needs, you could still use the last release by setting the MONOCLE_VERSION to 1.1.0 in the .env file. Please refer to System configuration section.

Create the config.yaml file

The config.yaml file is used by the crawler and api services.

To crawl GitHub public repositories, you must generate a personal access token on GitHub (w/o any specific rights) at

Then create the config file etc/config.yaml. Here is an example your could start with. Make sure to write GITHUB_TOKEN=<github_token> in the .secrets file:

  - name: monocle
      - name: github-tektoncd
          github_organization: tektoncd
            - operator
            - pipeline
        update_since: '2021-01-01'

To crawl the full tektoncd GitHub organization then remove the github_repositories entry from the file. Check the section Workspaces for a complete description of the configuration.

Start docker-compose

Start Monocle:

$ docker-compose up -d

Ensure services are running:

$ docker-compose ps

You might need to check the crawler logs to ensure the crawler started to fetch changes:

$ docker-compose logs -f crawler
$ docker-compose logs -f crawler-legacy

You should be able to access the web UI at http://localhost:8080.

After a change in the configuration file, the crawler-legacy service need to be restarted:

$ docker-compose restart crawler-legacy



For a local deployment, default settings are fine.

The following settings are available in the .env file:

  • MONOCLE_PUBLIC_URL=<url> to configure the public URL to access the UI and API. This is required for the github oauth redirection.
  • MONOCLE_VERSION=<version> to use a specific version. By default it uses latest.
  • MONOCLE_TITLE=<title> to change the title of the web application. By default it is Monocle.
  • ES_XMS and ES_XMX to change the ElasticSearch JVM HEAP SIZE. By default 512m.


The Monocle configuration file defines workspaces. The file is used by the API and crawlers processes. The format of the file is YAML. You might want to use Dhall to manage it or to better understand the schema (dhall-monocle).

A workspace uses a dedicated ElasticSearch index. A workspace defines:


Monocle provides two kinds of crawlers:

  • Change: A crawler to fetch Changes proposed to a repository. Monocle supports Gerrit (Reviews), GitHub (Pull-Requests), GitLab (Merge-Requests).
  • TaskData: A crawler to fetch task data related to a repository. Monocle supports GitHub (issues), and BugZilla (Bugs).

The .secrets file is used to store credentials and API keys used by crawlers to authenticate on providers.

The crawlers value is a list of crawler. Each crawler is composed of:

  • name: an abitrary name used to identify the crawler.
  • updated_since: the crawler will fetch changes that has been created/updated since that date.
  • provider: provider settings
  - name: demo
      - name: spinnaker
        updated_since: "2020-01-01"
        provider: {}

A GitHub provider settings

    github_organization: spinnaker
    # Optional settings
      - pipeline
    github_token: GITHUB_TOKEN

github_organization is the only mandatory key. If github_repositories is not specified then the crawler will crawl the whole organization repositories. If specified then it will crawl only the listed repositories.

github_url might be specified in case of an alternate url. Default is "".

github_token might be specified to use an alternate environment variable name to look for the token value. Default is "GITHUB_TOKEN"

To crawl privates repositories, either you must use a GitHub Application or you must generate a Personal Access Token with the "repo" scope.

Note that this crawler is managed by the crawler-legacy container.


A Gerrit provider settings

      - openstack/nova
      - openstack/neutron
    # Optional settings
    gerrit_login: monocle
    gerrit_password: GERRIT_PASSWORD
    gerrit_url_insecure: true
    gerrit_prefix: opendev/

gerrit_url is mandatory and must be the url of the Gerrit provider. gerrit_repositories is mandatory and is the list of repositories from which the crawler will fetch Reviews from.

gerrit_login might be specified to authenticate on the provider API. gerrit_passwordmight be specified to use an alternate environment variable name to look for the password. Default is "GERRIT_PASSWORD"

gerrit_url_insecure could be set to true to prevent HTTP certificate check.

gerrit_prefix might be set to configure the crawler to prepend the repository name with a prefix.


A GitLab provider settings

    gitlab_organization: redhat/centos-stream/ci-cd/zuul
    # Optional settings
      - jobs-config
    gitlab_token: GITLAB_TOKEN

gitlab_organization is the only mandatory key. If gitlab_repositories is not specified then the crawler will crawl the whole organization repositories. If specified then it will crawl only the listed repositories.

gitlab_url might be specified in case of an alternate url. Default is "".

gitlab_token might be specified to use an alternate environment variable name to look for the token value. Default is "GITLAB_TOKEN"

Note that this crawler is managed by the crawler container.


Monocle provides additional crawlers to attach tasks/issues/RFEs to changes based on a match on change_url. Then, Changes can be enhanced with information about related tasks such as a priority or a score.


The GitHub TaskData crawler run automatically whenever repositories are specified into a GitHub Changes crawler definition.


A BugZilla provider settings

      - Awesome product
    # Optional settings
    bugzilla_token: BUGZILLA_TOKEN

bugzilla_product must be specified. The crawler will crawl listed products for bugs that contain an external bug references ext_bz_bug_id. The crawler assumes that the external reference is used to link to a change (Pull-Request/Review).

bugzilla_token might be specified to use an alternate environment variable name to look for the token value. Default is "BUGZILLA_TOKEN"

Note that this crawler is managed by the crawler container.

Projects definition

Projects could be defined within a workspace configuration. A project is identified by a name and allows to set the following filter attributes:

  • repository_regex
  • branch_regex
  • file_regex

Here is an example of configuration.

  - name: example
      - name: openstack
            - ^openstack/.*
        updated_since: "2021-01-01"
      - name: compute
        repository_regex: ".*nova.*"
      - name: compute-tests
        file_regex: "test[s]/.*"
        repository_regex: ".*nova.*"
      - name: deployment
        repository_regex: ".*tripleo.*|.*puppet.*|.*ansible.*"
        branch_regex: "master"

The monocle API endpoint api/1/get_projects can be queried to retrieved the list defined projects for a given workspace. See the Monocle OpenAPI.

The monocle query endpoint handles the query parameter: project.

Identity Management

Monocle is able to index changes from multiple code review systems. A contributor might get different identities across code review systems. Thus Monocle provides a configuration section to define aliases for contributors.

Let say a Monocle workspace is configured to fetch changes from and (Gerrit) and we would like that John's metrics are merged under the John Doe identity.

  - name: example
      - ident: John Doe
          - Doe/12345
      - name: github-containers
          github_organization: containers
          github_token: <github_token>
        update_since: '2000-01-01'

      - name: gerrit-opendev
            - ^openstack/.*
        update_since: '2000-01-01'

A contributor id on or a GitHub enterprise instance is formated as <domain>/<login>.

A contributor id on a Gerrit instance is formated as <domain>/<Full Name>/<gerrit-user-id>.

Groups definition

A group in Monocle permits to group authors of Changes and filter them from the web interface.

Group memberships are defined through the idents section of the configuration.

Here is an example:

  - name: example
      - ident: John Doe
          - Doe/12345
          - devs
      - ident: Jane Doe
          - devs
          - ptl

Apply idents configuration

Database objects must be updated to reflect the configuration. Once config.yaml is updated, run the following commands:

docker-compose restart crawler-legacy
docker-compose run --rm --no-deps crawler-legacy /usr/local/bin/monocle --elastic-conn elastic:9200 dbmanage --workspace <workspace-name> --config /etc/monocle/config.yaml --update-idents

Full configuration file example

Here are the expected environment variables that need to be added to the .secrets file:

  • CRAWLERS_API_KEY: an arbitrary api key used by the crawler to index data.
  • GITHUB_TOKEN: an API key for GitHub crawler.
  • GITLAB_TOKEN: an API key for GitLab crawler.

Open the sample config.yaml.

GitHub application

Monocle can interact with a GitHub application to create and use installed application token to query the API.

Once the application is created and Monocle started with application id and private key. If a github_orgs entry's token attribute is missing Monocle will search accross the application installations for an installed application on the related GitHub organization. If any, it will generate an installation token for the matching installation and use it to query the GitHub API.

Create the application on GitHub

  1. Register new GitHub App
  2. In Repository permissions set Metadata as Read-Only, Pull requests as Read-Only and Contents as Read-Only
  3. Click Create the GitHub App
  4. Click Generate a private key and download the key
  5. Save the App ID

Setup Monocle to use the application

  1. Save the private key into etc/app_key.rsa
  2. Into the .secrets file add GITHUB_APP_ID=<APP_ID> and GITHUB_APP_KEY_PATH=/etc/monocle/app_key.rsa

Database migration

From version 0.8.X to next stable

Identities are consolidated in the database, to enable multiple code review identities (across code review systems) to be grouped.

  1. Run the migration process for each workspace
docker-compose stop
docker-compose start elastic
# For each workspace
docker-compose run --rm --no-deps crawler /usr/local/bin/monocle --elastic-conn elastic:9200 dbmanage --workspace <workspace-name> --run-migrate from-0.8-to-last-stable
docker-compose up -d

From version 0.7.0

A new field self_merged has been added. Previously indexed changes can be updated by running the self-merge migration process.

docker-compose run --rm --no-deps crawler /usr/local/bin/monocle --elastic-conn elastic:9200 dbmanage --workspace <index-name> --run-migrate self-merge


ElasticSearch could need some capabilities to run in container mode. Take a look at the logs to see if it started correctly:

$ docker-compose logs elastic

For example, you could need to increase this system parameter:

$ sudo sysctl -w vm.max_map_count=262144

or make the data directory writable for other:

$ chmod o+w data

You might want to wipe a Monocle project:

docker-compose run --rm --no-deps crawler-legacy /usr/local/bin/monocle \
--elastic-conn elastic:9200 dbmanage --workspace <workspace-name> --delete-repository ".*"

or delete a workspace:

docker-compose run --rm --no-deps crawler-legacy /usr/local/bin/monocle \
--elastic-conn elastic:9200 dbmanage --workspace <workspace-name> --delete-workspace

ElasticSearch sets defaults settings on new indexes. The default setting for queries based on regex is set to a value that might not fit your usage especially when your project definitions uses regex above that limit. However the limit could be increased using the following command:

docker-compose run --rm --no-deps crawler-legacy curl \
-XPUT http://localhost:9200/monocle.changes.1.<workspace-name>/_settings \
-H "Content-Type: application/json" -d '{"index": {"max_regex_length": 50000}}'



Monocle is composed of the following services:

  1. an Elasticsearch data store.
  2. an api service to perform user query and index crawler output.
  3. a crawler service to retrieve change from provider.
  4. a web proxy and web application to browse metrics.

The APIs are defined using protobuf and served over HTTP through Monocle OpenAPI.

Some legacy component are still required until they are migrated to the new OpenAPI (see the related topic):

  1. a crawler service to index github and gerrit changes.


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