ElasticSearch

Elasticsearch is an open-source, distributed search and analytics engine built on Apache Lucene. It handles textual, numerical, geospatial, structured, and unstructured data, providing high scalability and near real-time search. When full-text search volumes grow beyond what the internal engine handles comfortably, Elasticsearch is a common choice as an external search backend.

Configuration

The Elasticsearch backend is selected by choosing the ElasticSearch variant on the SearchStore object (found in the WebUI under Settings › Storage › Search Store). The variant exposes the following fields:

• url: URL of the Elasticsearch server or cluster endpoint (required).
• timeout: maximum time to wait for an HTTP response. Default: "30s".
• allowInvalidCerts: when true, accepts connections with invalid TLS certificates. Default: false.
• httpAuth: authentication method used for HTTP requests (required). The Unauthenticated, Basic, and Bearer variants are supported.
• httpHeaders: additional headers attached to every HTTP request.

Authentication

For HTTP Basic authentication, select the Basic variant of httpAuth and supply username and secret. For bearer-token authentication, select the Bearer variant and supply bearerToken. Secrets may be provided inline, read from an environment variable, or loaded from a file.

Index settings

Stalwart maps its search data to an Elasticsearch index whose shape is controlled by the following fields:

• numShards: number of primary shards for the index. Default: 3.
• numReplicas: number of replica shards per primary. Default: 0.
• includeSource: when true, indexes the full source document alongside the inverted index. Default: false.