GitLab Discovery

The GitLab integration has a special entity provider for discovering catalog entities from GitLab. The entity provider will crawl the GitLab instance and register entities matching the configured paths. This can be useful as an alternative to static locations or manually adding things to the catalog.

This provider can also be configured to ingest GitLab data based on GitLab Webhooks. The events currently accepted are:

• push.

Installation

As this provider is not one of the default providers, you will first need to install the gitlab catalog plugin:

# From your Backstage root directory
yarn --cwd packages/backend add @backstage/plugin-catalog-backend-module-gitlab

Installation with New Backend System

Then add the following to your backend initialization:

// optional if you want HTTP endpoints to receive external events
// backend.add(import('@backstage/plugin-events-backend/alpha'));
// optional if you want to use AWS SQS instead of HTTP endpoints to receive external events
// backend.add(import('@backstage/plugin-events-backend-module-aws-sqs/alpha'));
// optional - event router for gitlab. See.: https://github.com/backstage/backstage/blob/master/plugins/events-backend-module-gitlab/README.md
// backend.add(eventsModuleGitlabEventRouter());
// optional - token validator for the gitlab topic
// backend.add(eventsModuleGitlabWebhook());
backend.add(import('@backstage/plugin-catalog-backend-module-gitlab/alpha'));

You need to decide how you want to receive events from external sources like

• via HTTP endpoint
• via an AWS SQS queue

Further documentation:

• Events Plugin
• GitLab Module for the Events Plugin

Installation with Legacy Backend System

Installation without Events Support

Add the segment below to packages/backend/src/plugins/catalog.ts:

packages/backend/src/plugins/catalog.ts

import { GitlabDiscoveryEntityProvider } from '@backstage/plugin-catalog-backend-module-gitlab';

export default async function createPlugin(
  env: PluginEnvironment,
): Promise<Router> {
  const builder = await CatalogBuilder.create(env);
  builder.addEntityProvider(
    ...GitlabDiscoveryEntityProvider.fromConfig(env.config, {
      logger: env.logger,
      // optional: alternatively, use scheduler with schedule defined in app-config.yaml
      schedule: env.scheduler.createScheduledTaskRunner({
        frequency: { minutes: 30 },
        timeout: { minutes: 3 },
      }),
      // optional: alternatively, use schedule
      scheduler: env.scheduler,
    }),
  );
  // ..
}

Installation with Events Support

Please follow the installation instructions at

• Events Plugin
• GitLab Module for the Events Plugin

Additionally, you need to decide how you want to receive events from external sources like

• via HTTP endpoint
• via an AWS SQS queue

Set up your provider

packages/backend/src/plugins/catalog.ts

import { CatalogBuilder } from '@backstage/plugin-catalog-backend';
import { GitlabDiscoveryEntityProvider } from '@backstage/plugin-catalog-backend-module-gitlab';
import { ScaffolderEntitiesProcessor } from '@backstage/plugin-scaffolder-backend';
import { Router } from 'express';
import { PluginEnvironment } from '../types';

export default async function createPlugin(
  env: PluginEnvironment,
): Promise<Router> {
  const builder = await CatalogBuilder.create(env);
  builder.addProcessor(new ScaffolderEntitiesProcessor());
  const gitlabProvider = GitlabDiscoveryEntityProvider.fromConfig(env.config, {
    logger: env.logger,
    // optional: alternatively, use scheduler with schedule defined in app-config.yaml
    schedule: env.scheduler.createScheduledTaskRunner({
      frequency: { minutes: 30 },
      timeout: { minutes: 3 },
    }),
    // optional: alternatively, use schedule
    scheduler: env.scheduler,
  });
  env.eventBroker.subscribe(gitlabProvider);
  builder.addEntityProvider(gitlabProvider);
  const { processingEngine, router } = await builder.build();
  await processingEngine.start();
  return router;
}

Configuration

To use the discovery provider, you'll need a GitLab integration set up with a token. Then you can add a provider config per group to the catalog configuration.

NOTE: if you are using the New Backend System, the schedule has to be setup in the config, as shown below.

app-config.yaml

catalog:
  providers:
    gitlab:
      yourProviderId:
        host: gitlab-host # Identifies one of the hosts set up in the integrations
        branch: main # Optional. Used to discover on a specific branch
        fallbackBranch: master # Optional. Fallback to be used if there is no default branch configured at the Gitlab repository. It is only used, if `branch` is undefined. Uses `master` as default
        skipForkedRepos: false # Optional. If the project is a fork, skip repository
        group: example-group # Optional. Group and subgroup (if needed) to look for repositories. If not present the whole instance will be scanned
        entityFilename: catalog-info.yaml # Optional. Defaults to `catalog-info.yaml`
        projectPattern: '[\s\S]*' # Optional. Filters found projects based on provided patter. Defaults to `[\s\S]*`, which means to not filter anything
        schedule: # Same options as in TaskScheduleDefinition. Optional for the Legacy Backend System
          # supports cron, ISO duration, "human duration" as used in code
          frequency: { minutes: 30 }
          # supports ISO duration, "human duration" as used in code
          timeout: { minutes: 3 }

Alternative processor

As alternative to the entity provider GitlabDiscoveryEntityProvider you can still use the GitLabDiscoveryProcessor.

Note the gitlab-discovery type, as this is not a regular url processor.

The target is composed of three parts:

• The base URL, https://gitlab.com in this case
• The group path, group/subgroup in this case. This is optional: If you omit this path the processor will scan the entire GitLab instance instead.
• The path within each repository to find the catalog YAML file. This will usually be /blob/main/catalog-info.yaml, /blob/master/catalog-info.yaml or a similar variation for catalog files stored in the root directory of each repository. If you want to use the repository's default branch use the * wildcard, e.g.: /blob/*/catalog-info.yaml

Finally, you will have to add the processor in the catalog initialization code of your backend.

packages/backend/src/plugins/catalog.ts

import { GitLabDiscoveryProcessor } from '@backstage/plugin-catalog-backend-module-gitlab';

export default async function createPlugin(
  env: PluginEnvironment,
): Promise<Router> {
  const builder = await CatalogBuilder.create(env);
  builder.addProcessor(
    GitLabDiscoveryProcessor.fromConfig(env.config, { logger: env.logger }),
  );

  // ..
}

And add the following to your app-config.yaml

catalog:
  locations:
    - type: gitlab-discovery
      target: https://gitlab.com/group/subgroup/blob/main/catalog-info.yaml

If you don't want create location object if file with component definition do not exists in project, you can set the skipReposWithoutExactFileMatch option. That can reduce count of request to gitlab with 404 status code.

If you don't want to create location object if the project is a fork, you can set the skipForkedRepos option.