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Search Engines

Backstage supports 3 search engines by default, an in-memory engine called Lunr, ElasticSearch and Postgres. You can configure your own search engines by implementing the provided interface as mentioned in the search backend documentation.

Provided search engine implementations have their own way of constructing queries, which may be something you want to modify. Alterations to the querying logic of a search engine can be made by providing your own implementation of a QueryTranslator interface. This modification can be done without touching provided search engines by using the exposed setter to set the modified query translator into the instance.

const searchEngine = new LunrSearchEngine({ logger: env.logger });
searchEngine.setTranslator(new MyNewAndBetterQueryTranslator());

Lunr

Lunr search engine is enabled by default for your backstage instance if you have not done additional changes to the scaffolded app.

Lunr can be instantiated like this:

// app/backend/src/plugins/search.ts
const searchEngine = new LunrSearchEngine({ logger: env.logger });
const indexBuilder = new IndexBuilder({ logger: env.logger, searchEngine });

Postgres

The Postgres based search engine only requires that postgres being configured as the database engine for Backstage. Therefore it targets setups that want to avoid maintaining another external service like elastic search. The search provides decent results and performs well with ten thousands of indexed documents. The connection to postgres is established via the database manager also used by other plugins.

Important: The search plugin requires at least Postgres 12!

To use the PgSearchEngine, make sure that you have a Postgres database configured and make the following changes to your backend:

1. Add a dependency on @backstage/plugin-search-backend-module-pg to your backend's package.json.
2. Initialize the search engine. It is recommended to initialize it with a fallback to the lunr search engine if you are running Backstage for development locally with SQLite:

// In packages/backend/src/plugins/search.ts

// Initialize a connection to a search engine.
const searchEngine = (await PgSearchEngine.supported(env.database))
  ? await PgSearchEngine.from({ database: env.database })
  : new LunrSearchEngine({ logger: env.logger });

ElasticSearch

Backstage supports ElasticSearch search engine connections, indexing and querying out of the box. Available configuration options enable usage of either AWS or Elastic.co hosted solutions, or a custom self-hosted solution.

Similarly to Lunr above, ElasticSearch can be set up like this:

// app/backend/src/plugins/search.ts
const searchEngine = await ElasticSearchSearchEngine.initialize({
  logger: env.logger,
  config: env.config,
});
const indexBuilder = new IndexBuilder({ logger: env.logger, searchEngine });

For the engine to be available, your backend package needs a dependency into package @backstage/plugin-search-backend-module-elasticsearch.

ElasticSearch needs some additional configuration before it is ready to use within your instance. The configuration options are documented in the configuration schema definition file.

The underlying functionality is using official ElasticSearch client version 7.x, meaning that ElasticSearch version 7 is the only one confirmed to be supported.

Should you need to create your own bespoke search experiences that require more than just a query translator (such as faceted search or Relay pagination), you can access the configuration of the search engine in order to create new elastic search clients. The version of the client need not be the same as one used internally by the elastic search engine plugin. For example:

import { Client } from '@elastic/elastic-search';

const client = searchEngine.newClient(options => new Client(options));

Set custom index template

The elasticsearch engine gives you the ability to set a custom index template if needed.

Index templates define settings, mappings, and aliases that can be applied automatically to new indices.

// app/backend/src/plugins/search.ts
const searchEngine = await ElasticSearchSearchEngine.initialize({
  logger: env.logger,
  config: env.config,
});

searchEngine.setIndexTemplate({
  name: '<name-of-your-custom-template>',
  body: {
    index_patterns: ['<your-index-pattern>'],
    template: {
      mappings: {},
      settings: {},
    },
  },
});

Example configurations

AWS

Using AWS hosted ElasticSearch the only configuration option needed is the URL to the ElasticSearch service. The implementation assumes that environment variables for AWS access key id and secret access key are defined in accordance to the default AWS credential chain..

search:
  elasticsearch:
    provider: aws
    node: https://my-backstage-search-asdfqwerty.eu-west-1.es.amazonaws.com

Elastic.co

Elastic Cloud hosted ElasticSearch uses a Cloud ID to determine the instance of hosted ElasticSearch to connect to. Additionally, username and password needs to be provided either directly or using environment variables like defined in Backstage documentation.

search:
  elasticsearch:
    provider: elastic
    cloudId: backstage-elastic:asdfqwertyasdfqwertyasdfqwertyasdfqwerty==
    auth:
      username: elastic
      password: changeme

Others

Other ElasticSearch instances can be connected to by using standard ElasticSearch authentication methods and exposed URL, provided that the cluster supports that. The configuration options needed are the URL to the node and authentication information. Authentication can be handled by either providing username/password or an API key. For more information how to create an API key, see Elastic documentation on API keys.

Configuration examples

With username and password

search:
  elasticsearch:
    node: http://localhost:9200
    auth:
      username: elastic
      password: changeme

With API key

search:
  elasticsearch:
    node: http://localhost:9200
    auth:
      apiKey: base64EncodedKey