Add TermsAggregation implementation for grpc

Signed-off-by: Patrick Zhai <pzhai@uber.com>

Author: Patrick Zhai

.idea/vcs.xml

@@ -0,0 +1,12 @@
+{
+  "mcpServers": {
+    "code-mcp": {
+      "command": "aifx",
+      "args": [
+        "mcp",
+        "run",
+        "code-mcp"
+      ]
+    }
+  }
+}

.mcp.json

@@ -13,6 +13,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - [Workload Management] Enhance Scroll API support for autotagging ([#20151](https://github.com/opensearch-project/OpenSearch/pull/20151))
 - Add indices to search request slowlog ([#20588](https://github.com/opensearch-project/OpenSearch/pull/20588))
 - Add gRPC support for Min and Max metric aggregations ([#20676](https://github.com/opensearch-project/OpenSearch/pull/20676))
+- Add gRPC support for Term aggregations ([#20970](https://github.com/opensearch-project/OpenSearch/pull/20970))
 
 ### Changed
 - Move Randomness from server to libs/common ([#20570](https://github.com/opensearch-project/OpenSearch/pull/20570))

CHANGELOG.md

@@ -87,6 +87,11 @@ allprojects {
   group = 'org.opensearch'
   version = VersionProperties.getOpenSearch()
   description = "OpenSearch subproject ${project.path}"
+
+  // Add local Maven repository for protobuf development
+  repositories {
+    mavenLocal()
+  }
 }
 
 configure(allprojects - project(':distribution:archives:integ-test-zip')) {

build.gradle

@@ -15,8 +15,8 @@ base {
 }
 
 dependencies {
-  implementation project(":server")
-  implementation "org.opensearch:protobufs:${versions.opensearchprotobufs}"
+  api project(":server")
+  api "org.opensearch:protobufs:${versions.opensearchprotobufs}"
   implementation "io.grpc:grpc-api:${versions.grpc}"
   testImplementation project(":test:framework")
   testImplementation "io.grpc:grpc-services:${versions.grpc}"

modules/transport-grpc/spi/build.gradle

@@ -17,8 +17,9 @@
  * SPI interface for converting OpenSearch InternalAggregation objects to Protocol Buffer Aggregate messages.
  * Follows the same pattern as {@link AggregationBuilderProtoConverter} for request-side conversions.
  *
- * <p>The registry handles metadata centrally. Converters should delegate to existing
- * {@code *AggregateProtoUtils} classes for the actual conversion logic.
+ * <p>Implementations should extend {@code AbstractAggregateProtoConverter} which handles metadata
+ * centrally via the template method pattern, mirroring how {@code InternalAggregation.toXContent}
+ * handles metadata then delegates to {@code doXContentBody}.
  */
 public interface AggregateProtoConverter {
 

modules/transport-grpc/spi/src/main/java/org/opensearch/transport/grpc/spi/AggregateProtoConverter.java

@@ -476,10 +476,7 @@ public Collection<Object> createComponents(
 
         // Inject registry into external aggregation converters and register them
         if (!aggregationConverters.isEmpty()) {
-            logger.info(
-                "Injecting registry and registering {} external AggregationBuilderProtoConverter(s)",
-                aggregationConverters.size()
-            );
+            logger.info("Injecting registry and registering {} external AggregationBuilderProtoConverter(s)", aggregationConverters.size());
             for (AggregationBuilderProtoConverter converter : aggregationConverters) {
                 logger.info(
                     "Processing external aggregation converter: {} (handles: {})",
@@ -494,7 +491,10 @@ public Collection<Object> createComponents(
                 // Register the converter
                 aggregationRegistry.registerConverter(converter);
             }
-            logger.info("Successfully injected registry and registered all {} external aggregation converters", aggregationConverters.size());
+            logger.info(
+                "Successfully injected registry and registered all {} external aggregation converters",
+                aggregationConverters.size()
+            );
 
             // Update the registry on all converters (including built-in ones) so they can access external converters
             aggregationRegistry.updateRegistryOnAllConverters();
@@ -505,10 +505,7 @@ public Collection<Object> createComponents(
 
         // Register external aggregate converters (response-side)
         if (!aggregateConverters.isEmpty()) {
-            logger.info(
-                "Registering {} external AggregateProtoConverter(s)",
-                aggregateConverters.size()
-            );
+            logger.info("Registering {} external AggregateProtoConverter(s)", aggregateConverters.size());
             for (AggregateProtoConverter converter : aggregateConverters) {
                 logger.info(
                     "Processing external aggregate converter: {} (handles: {})",

modules/transport-grpc/src/main/java/org/opensearch/transport/grpc/GrpcPlugin.java

@@ -83,7 +83,14 @@ public static org.opensearch.action.search.SearchRequest prepareRequest(
          */
         IntConsumer setSize = size -> searchRequest.source().size(size);
         // TODO avoid hidden cast to NodeClient here
-        parseSearchRequest(searchRequest, request, ((NodeClient) client).getNamedWriteableRegistry(), setSize, queryUtils, aggregationRegistry);
+        parseSearchRequest(
+            searchRequest,
+            request,
+            ((NodeClient) client).getNamedWriteableRegistry(),
+            setSize,
+            queryUtils,
+            aggregationRegistry
+        );
         return searchRequest;
     }
 

modules/transport-grpc/src/main/java/org/opensearch/transport/grpc/proto/request/search/SearchRequestProtoUtils.java

@@ -200,7 +200,8 @@ private static void parseNonQueryFields(
                 DerivedField derivedFieldProto = entry.getValue();
 
                 // Convert protobuf DerivedField to OpenSearch DerivedField using the REST side pattern
-                // This uses simple constructor + conditional setters (matches {@link org.opensearch.index.mapper.DerivedFieldMapper.Builder#build()})
+                // This uses simple constructor + conditional setters (matches {@link
+                // org.opensearch.index.mapper.DerivedFieldMapper.Builder#build()})
                 org.opensearch.index.mapper.DerivedField derivedField = DerivedFieldProtoUtils.fromProto(name, derivedFieldProto);
 
                 // Add to SearchSourceBuilder - check if any optional fields are set to choose the right method

modules/transport-grpc/src/main/java/org/opensearch/transport/grpc/proto/request/search/SearchSourceBuilderProtoUtils.java

@@ -13,6 +13,7 @@
 import org.opensearch.common.inject.Singleton;
 import org.opensearch.protobufs.AggregationContainer;
 import org.opensearch.search.aggregations.AggregationBuilder;
+import org.opensearch.transport.grpc.proto.request.search.aggregation.bucket.terms.TermsAggregationBuilderConverter;
 import org.opensearch.transport.grpc.proto.request.search.aggregation.metrics.MaxAggregationBuilderProtoConverter;
 import org.opensearch.transport.grpc.proto.request.search.aggregation.metrics.MinAggregationBuilderProtoConverter;
 import org.opensearch.transport.grpc.spi.AggregationBuilderProtoConverter;
@@ -44,6 +45,7 @@ protected void registerBuiltInConverters() {
         // Register metric aggregation converters
         delegate.registerConverter(new MinAggregationBuilderProtoConverter());
         delegate.registerConverter(new MaxAggregationBuilderProtoConverter());
+        delegate.registerConverter(new TermsAggregationBuilderConverter());
 
         // Future: Register bucket aggregation converters here
         // Example: delegate.registerConverter(new TermsAggregationBuilderProtoConverter());