Move transport-grpc from a core plugin to a module

CHANGELOG.md

@@ -53,6 +53,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Change default value of remote_data_ratio, which is used in Searchable Snapshots and Writeable Warm from 0 to 5 and min allowed value to 1 ([#18767](https://github.com/opensearch-project/OpenSearch/pull/18767))
 - Making multi rate limiters in repository dynamic [#18069](https://github.com/opensearch-project/OpenSearch/pull/18069)
 - Optimize grouping for segment concurrent search by ensuring that documents within each group are as equal as possible ([#18451](https://github.com/opensearch-project/OpenSearch/pull/18451))
+- Move transport-grpc from a core plugin to a module ([#18897](https://github.com/opensearch-project/OpenSearch/pull/18897))
 
 ### Dependencies
 - Bump `stefanzweifel/git-auto-commit-action` from 5 to 6 ([#18524](https://github.com/opensearch-project/OpenSearch/pull/18524))

plugins/transport-grpc/README.md → modules/transport-grpc/README.md

@@ -1,7 +1,10 @@
 # transport-grpc
 
 An auxiliary transport which runs in parallel to the REST API.
-The `transport-grpc` plugin initializes a new client/server transport implementing a gRPC protocol on Netty4.
+The `transport-grpc` module initializes a new client/server transport implementing a gRPC protocol on Netty4.
+
+**Note:** As a module, transport-grpc is included by default with all OpenSearch installations. However, it remains opt-in and must be explicitly enabled via configuration settings.
+
 ## GRPC Settings
 Enable this transport with:
 
@@ -50,20 +53,28 @@ setting 'grpc.netty.worker_count',                      '2'
 setting 'grpc.netty.max_concurrent_connection_calls',   '200'
 setting 'grpc.netty.max_connection_age',                '500ms'
 setting 'grpc.netty.max_connection_idle',               '2m'
-setting 'grpc.netty.max_msg_size:                       '10mb'
+setting 'grpc.netty.max_msg_size',                      '10mb'
 setting 'grpc.netty.keepalive_timeout',                 '1s'
 ```
 
 ## Testing
 
 ### Unit Tests
 
-```
-./gradlew :plugins:transport-grpc:test
+```bash
+./gradlew :modules:transport-grpc:test
 ```
 
 ### Integration Tests
 
+```bash
+./gradlew :modules:transport-grpc:internalClusterTest
 ```
-./gradlew :plugins:transport-grpc:internalClusterTest
+
+### Running OpenSearch with gRPC Enabled
+
+To run OpenSearch with the gRPC transport enabled:
+
+```bash
+./gradlew run -Dtests.opensearch.aux.transport.types="[experimental-transport-grpc]"
 ```

plugins/transport-grpc/build.gradle → modules/transport-grpc/build.gradle

@@ -16,7 +16,6 @@ opensearchplugin {
 
 testClusters {
   integTest {
-    plugin(project.path)
     setting 'aux.transport.types', '[experimental-transport-grpc]'
   }
 }