Doc: Add docs for extending integrations with filter-elastic_integrations (#15518) (#15674)

(cherry picked from commit 6c2e123a24)

Co-authored-by: Karen Metts <35154725+karenzone@users.noreply.github.com>

docs/index.asciidoc

@@ -135,6 +135,10 @@ include::static/config-management.asciidoc[]
 
 include::static/management/configuring-centralized-pipelines.asciidoc[]
 
+// EA Integrations to Logstash 
+// (Planting near module content for now. Will likely move it up in info architecture.)
+include::static/ea-integrations.asciidoc[]
+
 // Working with Logstash Modules
 include::static/modules.asciidoc[]
 

docs/static/ea-integrations.asciidoc

@@ -0,0 +1,79 @@
+[[ea-integrations]]
+== Using {ls} with Elastic {integrations} (Beta)
+
+You can take advantage of the extensive, built-in capabilities of Elastic {integrations}--such as managing data collection, transformation, and visualization--and then use {ls} for additional data processing and output options. 
+{ls} can further expand capabilities for use cases where you need additional processing, or if you need your data delivered to multiple destinations. 
+
+[discrete]
+[[integrations-value]]
+=== Elastic {integrations}: ingesting to visualizing 
+
+https://docs.elastic.co/integrations[Elastic {integrations}] provide quick, end-to-end solutions for:
+
+* ingesting data from a variety of data sources
+* getting the data into the {stack}, and 
+* visualizing it with purpose-built dashboards.
+
+{integrations} are available for https://docs.elastic.co/integrations/all_integrations[popular services and platforms], such as Nginx, AWS, and MongoDB, as well as many generic input types like log files.
+Each integration includes pre-packaged assets to help reduce the time between ingest and insights. 
+
+To see available integrations, go to the {kib} home page, and click **Add {integrations}**. 
+You can use the query bar to search for integrations you may want to use. 
+When you find an integration for your data source, the UI walks you through adding and configuring it. 
+
+[discrete]
+[[integrations-and-ls]]
+=== Extend {integrations} with {ls} (Beta)
+
+Logstash can run the ingest pipeline component of your integration when you use the Logstash filter-elastic_integration plugin. 
+
+.How to
+
+****
+Create a {ls} pipeline that uses the <<plugins-inputs-elastic_agent,elastic_agent input>> plugin, and the https://github.com/elastic/logstash-filter-elastic_integration[logstash-filter-elastic_integration] plugin as the _first_ filter in your {ls} pipeline.
+You can add more filters for additional processing, but they must come after the `logstash-filter-elastic_integration` plugin in your configuration. 
+Add an output plugin to complete your pipeline. 
+**** 
+
+
+**Sample pipeline configuration**
+
+[source,ruby]
+-----
+input {
+  elastic_agent { 
+    port => 5044
+  }
+}
+
+filter {
+  elastic_integration{ <1>
+    cloud_id => "<cloud id>"
+    cloud_auth => "<your_cloud-auth"    
+  }
+
+  translate { <2>
+    source => "[http][host]"
+    target => "[@metadata][tenant]"
+    dictionary_path => "/etc/conf.d/logstash/tenants.yml"
+  }
+}
+
+output { <3>
+  if [@metadata][tenant] == "tenant01" {
+    elasticsearch {
+      cloud_id => "<cloud id>"
+      api_key => "<api key>"
+    }
+  } else if [@metadata][tenant] == "tenant02" {
+    elasticsearch {
+      cloud_id => "<cloud id>"
+      api_key => "<api key>"
+    }
+  }
+}
+-----
+
+<1> Use `filter-elastic_agent` as the first filter in your pipeline 
+<2> You can use additional filters as long as they follow `filter-elastic_agent`
+<3> Sample config to output data to multiple destinations