logstash/docs/reference/plugin-concepts.md

mapped_pages
https://www.elastic.co/guide/en/logstash/current/plugin-concepts.html

Cross-plugin concepts and features [plugin-concepts]

New section for concepts, features, and behaviours that apply to multiple plugins.

Space-deliminated URIs in list-type params [space-delimited-uris-in-list-params]

List-type URI parameters will automatically expand strings that contain multiple whitespace-delimited URIs into separate entries. This behaviour enables the expansion of an arbitrary list of URIs from a single Environment- or Keystore-variable.

These plugins and options support this functionality:

• Elasticsearch input plugin - hosts
• Elasticsearch output plugin - hosts
• Elasticsearch filter plugin - hosts

You can use this functionality to define an environment variable with multiple whitespace-delimited URIs and use it for the options above.

Example

ES_HOSTS="es1.example.com es2.example.com:9201 es3.example.com:9201"