[[plugin-concepts]]
=== Cross-plugin concepts and features

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

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

* <<plugins-inputs-elasticsearch-hosts,Elasticsearch input plugin - `hosts`>>
* <<plugins-outputs-elasticsearch-hosts,Elasticsearch output plugin - `hosts`>>
* <<plugins-filters-elasticsearch-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"
```