Add gRPC support for Min and Max metric aggregations

CHANGELOG.md

@@ -12,6 +12,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Add range validations in query builder and field mapper ([#20497](https://github.com/opensearch-project/OpenSearch/issues/20497))
 - [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))
 
 ### Changed
 - Move Randomness from server to libs/common ([#20570](https://github.com/opensearch-project/OpenSearch/pull/20570))

buildSrc/build.gradle

@@ -94,6 +94,7 @@ tasks.withType(JavaCompile).configureEach {
  *****************************************************************************/
 
 repositories {
+  mavenLocal()
   mavenCentral()
   gradlePluginPortal()
 }

gradle/libs.versions.toml

@@ -24,7 +24,7 @@ kotlin                  = "1.7.10"
 antlr4                  = "4.13.1"
 guava                   = "33.2.1-jre"
 gson                    = "2.13.2"
-opensearchprotobufs     = "1.2.0"
+opensearchprotobufs     = "1.4.0-SNAPSHOT"
 protobuf                = "3.25.8"
 jakarta_annotation      = "1.3.5"
 google_http_client      = "1.44.1"

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

@@ -0,0 +1,42 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.transport.grpc.spi;
+
+import org.opensearch.protobufs.Aggregate;
+import org.opensearch.search.aggregations.InternalAggregation;
+
+import java.io.IOException;
+
+/**
+ * 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.
+ */
+public interface AggregateProtoConverter {
+
+    /**
+     * Returns the InternalAggregation subclass this converter handles.
+     *
+     * @return The class type of the aggregation this converter supports
+     */
+    Class<? extends InternalAggregation> getHandledAggregationType();
+
+    /**
+     * Converts an InternalAggregation to its Protocol Buffer Aggregate.Builder representation.
+     * Returns a builder to allow the registry to construct the final Aggregate.
+     * Mirrors REST-side {@link org.opensearch.search.aggregations.InternalAggregation#toXContent}
+     *
+     * @param aggregation The InternalAggregation to convert (guaranteed to be of the handled type)
+     * @return An Aggregate.Builder with the aggregation-specific fields populated
+     * @throws IOException if an error occurs during protobuf conversion
+     */
+    Aggregate.Builder toProto(InternalAggregation aggregation) throws IOException;
+}

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

@@ -0,0 +1,32 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.transport.grpc.spi;
+
+import org.opensearch.protobufs.Aggregate;
+import org.opensearch.search.aggregations.InternalAggregation;
+
+import java.io.IOException;
+
+/**
+ * SPI interface for the aggregate converter registry.
+ * Provides the main entry point for converting InternalAggregation objects to Protocol Buffer Aggregate messages.
+ */
+public interface AggregateProtoConverterRegistry {
+
+    /**
+     * Converts an InternalAggregation to its Protocol Buffer Aggregate representation.
+     * Handles metadata and delegates to the appropriate converter.
+     *
+     * @param aggregation The InternalAggregation to convert (must not be null)
+     * @return The corresponding Protocol Buffer Aggregate message
+     * @throws IllegalArgumentException if aggregation is null or type is not supported
+     * @throws IOException if an error occurs during protobuf conversion
+     */
+    Aggregate toProto(InternalAggregation aggregation) throws IOException;
+}

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

@@ -0,0 +1,44 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.transport.grpc.spi;
+
+import org.opensearch.protobufs.AggregationContainer;
+import org.opensearch.search.aggregations.AggregationBuilder;
+
+/**
+ * SPI interface for converting protobuf aggregation containers to OpenSearch AggregationBuilders.
+ * Follows the same pattern as {@link QueryBuilderProtoConverter}.
+ *
+ * <p>The registry handles metadata and subaggregations. Converters should delegate to existing
+ * {@code *ProtoUtils} classes.
+ *
+ * @see org.opensearch.search.aggregations.AggregatorFactories#parseAggregators
+ */
+public interface AggregationBuilderProtoConverter {
+
+    /**
+     * Returns the aggregation case this converter handles.
+     */
+    AggregationContainer.AggregationContainerCase getHandledAggregationCase();
+
+    /**
+     * Converts a protobuf aggregation container to an AggregationBuilder.
+     * Similar to {@link org.opensearch.search.aggregations.AggregatorFactories.Builder#addAggregator}.
+     *
+     * @param name The aggregation name
+     * @param container The protobuf container
+     * @return The OpenSearch AggregationBuilder
+     */
+    AggregationBuilder fromProto(String name, AggregationContainer container);
+
+    /**
+     * Sets the registry for nested aggregations. Default no-op for metric aggregations.
+     */
+    default void setRegistry(AggregationBuilderProtoConverterRegistry registry) {}
+}

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

@@ -0,0 +1,31 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.transport.grpc.spi;
+
+import org.opensearch.protobufs.AggregationContainer;
+import org.opensearch.search.aggregations.AggregationBuilder;
+
+/**
+ * SPI interface for the aggregation converter registry.
+ * Handles converter lookup, metadata, and recursive subaggregation parsing.
+ *
+ * @see org.opensearch.search.aggregations.AggregatorFactories#parseAggregators
+ */
+public interface AggregationBuilderProtoConverterRegistry {
+
+    /**
+     * Converts a protobuf aggregation container to an OpenSearch AggregationBuilder.
+     * Similar to {@link org.opensearch.search.aggregations.AggregatorFactories#parseAggregators}.
+     *
+     * @param name The aggregation name
+     * @param container The protobuf container
+     * @return The AggregationBuilder with metadata and subaggregations
+     */
+    AggregationBuilder fromProto(String name, AggregationContainer container);
+}

modules/transport-grpc/src/internalClusterTest/java/org/opensearch/transport/grpc/SearchServiceIT.java

@@ -8,6 +8,10 @@
 
 package org.opensearch.transport.grpc;
 
+import org.opensearch.protobufs.Aggregate;
+import org.opensearch.protobufs.AggregationContainer;
+import org.opensearch.protobufs.MaxAggregation;
+import org.opensearch.protobufs.MinAggregation;
 import org.opensearch.protobufs.SearchRequest;
 import org.opensearch.protobufs.SearchRequestBody;
 import org.opensearch.protobufs.SearchResponse;
@@ -57,4 +61,86 @@ public void testSearchServiceSearch() throws Exception {
             assertEquals("Hit should have correct ID", "1", searchResponse.getHits().getHits(0).getXId());
         }
     }
+
+    /**
+     * Tests min aggregation via gRPC.
+     */
+    public void testMinAggregation() throws Exception {
+        // Create a test index
+        String indexName = "test-min-agg";
+        createTestIndex(indexName);
+
+        // Index documents with different price values
+        indexTestDocument(indexName, "1", "{\"price\": 10.5}");
+        indexTestDocument(indexName, "2", "{\"price\": 25.0}");
+        indexTestDocument(indexName, "3", "{\"price\": 5.2}");
+
+        // Create a gRPC client
+        try (NettyGrpcClient client = createGrpcClient()) {
+            ManagedChannel channel = client.getChannel();
+            SearchServiceGrpc.SearchServiceBlockingStub searchStub = SearchServiceGrpc.newBlockingStub(channel);
+
+            // Build min aggregation request
+            MinAggregation minAgg = MinAggregation.newBuilder().setField("price").build();
+
+            SearchRequestBody requestBody = SearchRequestBody.newBuilder()
+                .setSize(0)
+                .putAggregations("min_price", AggregationContainer.newBuilder().setMin(minAgg).build())
+                .build();
+
+            SearchRequest searchRequest = SearchRequest.newBuilder().addIndex(indexName).setSearchRequestBody(requestBody).build();
+
+            // Execute search
+            SearchResponse response = searchStub.search(searchRequest);
+
+            // Verify min aggregation result
+            assertNotNull("Search response should not be null", response);
+            assertTrue("Should have aggregations", response.getAggregationsCount() > 0);
+            Aggregate minResult = response.getAggregationsMap().get("min_price");
+            assertNotNull("Min aggregation should exist", minResult);
+            assertTrue("Should have value", minResult.hasValue());
+            assertEquals("Min value should be 5.2", 5.2, minResult.getValue().getDouble(), 0.001);
+        }
+    }
+
+    /**
+     * Tests max aggregation via gRPC.
+     */
+    public void testMaxAggregation() throws Exception {
+        // Create a test index
+        String indexName = "test-max-agg";
+        createTestIndex(indexName);
+
+        // Index documents with different price values
+        indexTestDocument(indexName, "1", "{\"price\": 10.5}");
+        indexTestDocument(indexName, "2", "{\"price\": 25.0}");
+        indexTestDocument(indexName, "3", "{\"price\": 5.2}");
+
+        // Create a gRPC client
+        try (NettyGrpcClient client = createGrpcClient()) {
+            ManagedChannel channel = client.getChannel();
+            SearchServiceGrpc.SearchServiceBlockingStub searchStub = SearchServiceGrpc.newBlockingStub(channel);
+
+            // Build max aggregation request
+            MaxAggregation maxAgg = MaxAggregation.newBuilder().setField("price").build();
+
+            SearchRequestBody requestBody = SearchRequestBody.newBuilder()
+                .setSize(0)
+                .putAggregations("max_price", AggregationContainer.newBuilder().setMax(maxAgg).build())
+                .build();
+
+            SearchRequest searchRequest = SearchRequest.newBuilder().addIndex(indexName).setSearchRequestBody(requestBody).build();
+
+            // Execute search
+            SearchResponse response = searchStub.search(searchRequest);
+
+            // Verify max aggregation result
+            assertNotNull("Search response should not be null", response);
+            assertTrue("Should have aggregations", response.getAggregationsCount() > 0);
+            Aggregate maxResult = response.getAggregationsMap().get("max_price");
+            assertNotNull("Max aggregation should exist", maxResult);
+            assertTrue("Should have value", maxResult.hasValue());
+            assertEquals("Max value should be 25.0", 25.0, maxResult.getValue().getDouble(), 0.001);
+        }
+    }
 }