update codeowners file + add data_usage readme (#216486)

.github/CODEOWNERS

@@ -865,7 +865,7 @@ x-pack/platform/plugins/private/cloud_integrations/cloud_full_story @elastic/kib
 x-pack/platform/plugins/private/cloud_integrations/cloud_links @elastic/kibana-core
 x-pack/platform/plugins/private/cross_cluster_replication @elastic/kibana-management
 x-pack/platform/plugins/private/custom_branding @elastic/appex-sharedux
-x-pack/platform/plugins/private/data_usage @elastic/obs-ai-assistant @elastic/security-solution
+x-pack/platform/plugins/private/data_usage @elastic/kibana-management
 x-pack/platform/plugins/private/data_visualizer @elastic/ml-ui
 x-pack/platform/plugins/private/discover_enhanced @elastic/kibana-data-discovery
 x-pack/platform/plugins/private/drilldowns/url_drilldown @elastic/appex-sharedux
@@ -1304,9 +1304,9 @@ src/platform/plugins/shared/discover/public/context_awareness/profile_providers/
 ### Observability Plugins
 
 # Observability AI Assistant
-/x-pack/test_serverless/api_integration/test_suites/common/data_usage @elastic/obs-ai-assistant @elastic/security-solution
-/x-pack/test_serverless/functional/test_suites/common/data_usage @elastic/obs-ai-assistant @elastic/security-solution
-/x-pack/test_serverless/functional/page_objects/svl_data_usage.ts @elastic/obs-ai-assistant @elastic/security-solution
+/x-pack/test_serverless/api_integration/test_suites/common/data_usage @elastic/kibana-management
+/x-pack/test_serverless/functional/test_suites/common/data_usage @elastic/kibana-management
+/x-pack/test_serverless/functional/page_objects/svl_data_usage.ts @elastic/kibana-management
 /x-pack/test/observability_ai_assistant_api_integration @elastic/obs-ai-assistant
 /x-pack/test/observability_ai_assistant_functional @elastic/obs-ai-assistant
 /x-pack/test_serverless/**/test_suites/observability/ai_assistant @elastic/obs-ai-assistant

docs/extend/plugin-list.md

@@ -133,7 +133,7 @@ mapped_pages:
 | [dashboardEnhanced](dashboard-enhanced-plugin.md) | Adds drilldown capabilities to dashboard.  Owned by the Kibana App team. |
 | [dataQuality](https://github.com/elastic/kibana/blob/main/x-pack/platform/plugins/shared/data_quality/README.md) | Page where users can see the quality of their log data sets. |
 | [datasetQuality](https://github.com/elastic/kibana/blob/main/x-pack/platform/plugins/shared/dataset_quality/README.md) | In order to make ongoing maintenance of log collection easy we want to introduce the concept of data set quality, where users can easily get an overview on the data sets they have with information such as integration, size, last activity, among others. |
-| [dataUsage](https://github.com/elastic/kibana/blob/main/x-pack/platform/plugins/private/data_usage/README.md) | Serverless only plugin for users to view data usage |
+| [dataUsage](https://github.com/elastic/kibana/blob/main/x-pack/platform/plugins/private/data_usage/README.md) | Serverless-only plugin for users to view data usage. Available in all 3 solutions. |
 | [dataVisualizer](https://github.com/elastic/kibana/blob/main/x-pack/platform/plugins/private/data_visualizer/README.md) | The data_visualizer plugin enables you to explore the fields in your data. |
 | [discoverEnhanced](https://github.com/elastic/kibana/blob/main/x-pack/platform/plugins/private/discover_enhanced/README.md) | Contains the enhancements to the OSS discover app. |
 | [ecsDataQualityDashboard](https://github.com/elastic/kibana/blob/main/x-pack/solutions/security/plugins/ecs_data_quality_dashboard/README.md) | This plugin implements (server) APIs used to render the content of the Data Quality dashboard. |

x-pack/platform/plugins/private/data_usage/README.md

@@ -1,3 +1,53 @@
 # dataUsage
-Serverless only plugin for users to view data usage
 
+Serverless-only plugin for users to view data usage. Available in all 3 solutions.
+
+# API
+
+- **/api/data_usage/data_streams**
+
+  - Calls `/_metering/stats` to get list of data streams and size in bytes
+  - Filters out system data streams and empty data streams (0 bytes)
+  - Returns list of data streams sorted by storage size (highest)
+
+- **/api/data_usage/usage_metrics**
+  - With list of data streams, date range, and metric types
+  - Only two metric types right now, data ingested and data retained
+  - Requests data streams in chunks of 50 from es client with the internal user
+  - Call AutoOps API and return time series data
+
+# Integration with AutoOps
+
+- Plugin enforces mutual TLS (mTLS) when communicating with AutoOps
+- `appContextService` started in server-side plugin provides kibana config, cloud data, kibana data for communicating with AutoOps API
+- In serverless projects, Kibana config is controlled by the project-controller. We set the Data Usage AutoOps configuration for Kibana instances in all Serverless projects in the kibana controller.
+
+# Kibana config
+
+```
+xpack.dataUsage.autoops.enabled
+xpack.dataUsage.autoops.api.url
+xpack.dataUsage.autoops.api.tls.certificate
+xpack.dataUsage.autoops.api.tls.key
+```
+
+# Privileges
+
+Plugin only displays if user has cluster: `['monitor']` privilege in Elasticsearch (eg built in admin, developer or custom role).
+
+# Tests
+
+Functional
+
+- [[Data Usage] functional tests #203166](https://github.com/elastic/kibana/pull/203166)
+- [[Data Usage] add functional tests for privileges](https://github.com/elastic/kibana/pull/199377)
+
+API Integration tests
+
+- [[Data Usage] setup integration tests #197112](https://github.com/elastic/kibana/pull/197112)
+
+Unit tests
+
+- Route handlers
+- Utils
+- Hooks

x-pack/platform/plugins/private/data_usage/kibana.jsonc

@@ -2,8 +2,7 @@
   "type": "plugin",
   "id": "@kbn/data-usage-plugin",
   "owner": [
-    "@elastic/obs-ai-assistant",
-    "@elastic/security-solution"
+    "@elastic/kibana-management"
   ],
   "group": "platform",
   "visibility": "private",