xds: Support least_request LB in LoadBalancingPolicy (grpc#9262)

Author: temawi

repositories.bzl

@@ -135,10 +135,10 @@ def grpc_java_repositories():
     if not native.existing_rule("envoy_api"):
         http_archive(
             name = "envoy_api",
-            sha256 = "621577591d48cee20b61d4e71466bf4019791f9991da4813ccf75f3b9898de5f",
-            strip_prefix = "data-plane-api-bb6d6abe8b4d035c2f4ba3acf924cec0cbec5f70",
+            sha256 = "a0c58442cc2038ccccad9616dd1bab5ff1e65da2bbc0ae41020ef6010119eb0e",
+            strip_prefix = "data-plane-api-869b00336913138cad96a653458aab650c4e70ea",
             urls = [
-                "https://github.com/envoyproxy/data-plane-api/archive/bb6d6abe8b4d035c2f4ba3acf924cec0cbec5f70.tar.gz",
+                "https://github.com/envoyproxy/data-plane-api/archive/869b00336913138cad96a653458aab650c4e70ea.tar.gz",
             ],
         )
 

xds/BUILD.bazel

@@ -83,6 +83,7 @@ java_proto_library(
         "@envoy_api//envoy/extensions/filters/http/rbac/v3:pkg",
         "@envoy_api//envoy/extensions/filters/http/router/v3:pkg",
         "@envoy_api//envoy/extensions/filters/network/http_connection_manager/v3:pkg",
+        "@envoy_api//envoy/extensions/load_balancing_policies/least_request/v3:pkg",
         "@envoy_api//envoy/extensions/load_balancing_policies/ring_hash/v3:pkg",
         "@envoy_api//envoy/extensions/load_balancing_policies/round_robin/v3:pkg",
         "@envoy_api//envoy/extensions/load_balancing_policies/wrr_locality/v3:pkg",

xds/src/main/java/io/grpc/xds/LoadBalancerConfigFactory.java

@@ -28,6 +28,7 @@
 import io.envoyproxy.envoy.config.cluster.v3.Cluster.RingHashLbConfig;
 import io.envoyproxy.envoy.config.cluster.v3.LoadBalancingPolicy;
 import io.envoyproxy.envoy.config.cluster.v3.LoadBalancingPolicy.Policy;
+import io.envoyproxy.envoy.extensions.load_balancing_policies.least_request.v3.LeastRequest;
 import io.envoyproxy.envoy.extensions.load_balancing_policies.ring_hash.v3.RingHash;
 import io.envoyproxy.envoy.extensions.load_balancing_policies.round_robin.v3.RoundRobin;
 import io.envoyproxy.envoy.extensions.load_balancing_policies.wrr_locality.v3.WrrLocality;
@@ -167,6 +168,8 @@ static class LoadBalancingPolicyConverter {
                 recursionDepth);
           } else if (typedConfig.is(RoundRobin.class)) {
             serviceConfig = convertRoundRobinConfig();
+          } else if (typedConfig.is(LeastRequest.class)) {
+            serviceConfig = convertLeastRequestConfig(typedConfig.unpack(LeastRequest.class));
           } else if (typedConfig.is(com.github.xds.type.v3.TypedStruct.class)) {
             serviceConfig = convertCustomConfig(
                 typedConfig.unpack(com.github.xds.type.v3.TypedStruct.class));
@@ -231,6 +234,15 @@ static class LoadBalancingPolicyConverter {
       return buildRoundRobinConfig();
     }
 
+    /**
+     * Converts a least_request {@link Any} configuration to service config format.
+     */
+    private static ImmutableMap<String, ?> convertLeastRequestConfig(LeastRequest leastRequest)
+        throws ResourceInvalidException {
+      return buildLeastRequestConfig(
+          leastRequest.hasChoiceCount() ? leastRequest.getChoiceCount().getValue() : null);
+    }
+
     /**
      * Converts a custom TypedStruct LB config to service config format.
      */

xds/src/test/java/io/grpc/xds/LoadBalancerConfigFactoryTest.java

@@ -36,6 +36,7 @@
 import io.envoyproxy.envoy.config.cluster.v3.LoadBalancingPolicy;
 import io.envoyproxy.envoy.config.cluster.v3.LoadBalancingPolicy.Policy;
 import io.envoyproxy.envoy.config.core.v3.TypedExtensionConfig;
+import io.envoyproxy.envoy.extensions.load_balancing_policies.least_request.v3.LeastRequest;
 import io.envoyproxy.envoy.extensions.load_balancing_policies.ring_hash.v3.RingHash;
 import io.envoyproxy.envoy.extensions.load_balancing_policies.round_robin.v3.RoundRobin;
 import io.envoyproxy.envoy.extensions.load_balancing_policies.wrr_locality.v3.WrrLocality;
@@ -71,6 +72,12 @@ public class LoadBalancerConfigFactoryTest {
               .setMaximumRingSize(UInt64Value.of(RING_HASH_MAX_RING_SIZE))
               .setHashFunction(RingHash.HashFunction.XX_HASH).build()))).build();
 
+  private static final int LEAST_REQUEST_CHOICE_COUNT = 10;
+  private static final Policy LEAST_REQUEST_POLICY = Policy.newBuilder().setTypedExtensionConfig(
+      TypedExtensionConfig.newBuilder().setTypedConfig(Any.pack(
+          LeastRequest.newBuilder().setChoiceCount(UInt32Value.of(LEAST_REQUEST_CHOICE_COUNT))
+              .build()))).build();
+
   private static final String CUSTOM_POLICY_NAME = "myorg.MyCustomLeastRequestPolicy";
   private static final String CUSTOM_POLICY_FIELD_KEY = "choiceCount";
   private static final double CUSTOM_POLICY_FIELD_VALUE = 2;
@@ -103,6 +110,9 @@ public class LoadBalancerConfigFactoryTest {
       "wrr_locality_experimental", ImmutableMap.of("childPolicy", ImmutableList.of(
       ImmutableMap.of(VALID_CUSTOM_CONFIG.getPolicyName(),
           VALID_CUSTOM_CONFIG.getRawConfigValue()))));
+  private static final LbConfig VALID_LEAST_REQUEST_CONFIG = new LbConfig(
+      "least_request_experimental",
+      ImmutableMap.of("choiceCount", (double) LEAST_REQUEST_CHOICE_COUNT));
 
   @After
   public void deregisterCustomProvider() {
@@ -162,13 +172,23 @@ public void ringHash_invalidHash_legacy() {
     assertResourceInvalidExceptionThrown(cluster, true, true, "invalid ring hash function");
   }
 
+  @Test
+  public void leastRequest() throws ResourceInvalidException {
+    Cluster cluster = Cluster.newBuilder()
+        .setLoadBalancingPolicy(LoadBalancingPolicy.newBuilder().addPolicies(LEAST_REQUEST_POLICY))
+        .build();
+
+    assertThat(newLbConfig(cluster, true, true)).isEqualTo(VALID_LEAST_REQUEST_CONFIG);
+  }
+
   @Test
   public void leastRequest_legacy() throws ResourceInvalidException {
     System.setProperty("io.grpc.xds.experimentalEnableLeastRequest", "true");
 
     Cluster cluster = Cluster.newBuilder().setLbPolicy(LbPolicy.LEAST_REQUEST)
         .setLeastRequestLbConfig(
-            LeastRequestLbConfig.newBuilder().setChoiceCount(UInt32Value.of(10))).build();
+            LeastRequestLbConfig.newBuilder()
+                .setChoiceCount(UInt32Value.of(LEAST_REQUEST_CHOICE_COUNT))).build();
 
     LbConfig lbConfig = newLbConfig(cluster, true, true);
     assertThat(lbConfig.getPolicyName()).isEqualTo("wrr_locality_experimental");
@@ -178,7 +198,7 @@ public void leastRequest_legacy() throws ResourceInvalidException {
     assertThat(childConfigs.get(0).getPolicyName()).isEqualTo("least_request_experimental");
     assertThat(
         JsonUtil.getNumberAsLong(childConfigs.get(0).getRawConfigValue(), "choiceCount")).isEqualTo(
-        10);
+        LEAST_REQUEST_CHOICE_COUNT);
   }
 
   @Test