feat: apply grpc service config from consul (grpc-ecosystem#1045)

grpc-client-spring-boot-autoconfigure/src/main/java/net/devh/boot/grpc/client/nameresolver/DiscoveryClientNameResolver.java

@@ -22,7 +22,10 @@
 import static net.devh.boot.grpc.client.nameresolver.DiscoveryClientResolverFactory.DISCOVERY_INSTANCE_ID_KEY;
 import static net.devh.boot.grpc.client.nameresolver.DiscoveryClientResolverFactory.DISCOVERY_SERVICE_NAME_KEY;
 import static net.devh.boot.grpc.common.util.GrpcUtils.CLOUD_DISCOVERY_METADATA_PORT;
+import static net.devh.boot.grpc.common.util.GrpcUtils.CLOUD_DISCOVERY_METADATA_SERVICE_CONFIG;
 
+import com.google.gson.Gson;
+import com.google.gson.JsonSyntaxException;
 import java.net.InetSocketAddress;
 import java.util.List;
 import java.util.Map;
@@ -58,13 +61,15 @@ public class DiscoveryClientNameResolver extends NameResolver {
     @Deprecated
     private static final String LEGACY_CLOUD_DISCOVERY_METADATA_PORT = "gRPC.port";
     private static final List<ServiceInstance> KEEP_PREVIOUS = null;
+    private static final Gson GSON = new Gson();
 
     private final String name;
     private final DiscoveryClient client;
     private final SynchronizationContext syncContext;
     private final Consumer<DiscoveryClientNameResolver> shutdownHook;
     private final SharedResourceHolder.Resource<Executor> executorResource;
     private final boolean usingExecutorResource;
+    private final ServiceConfigParser serviceConfigParser;
 
     // The field must be accessed from syncContext, although the methods on an Listener2 can be called
     // from any thread.
@@ -93,6 +98,7 @@ public DiscoveryClientNameResolver(final String name, final DiscoveryClient clie
         this.executor = args.getOffloadExecutor();
         this.usingExecutorResource = this.executor == null;
         this.executorResource = executorResource;
+        this.serviceConfigParser = args.getServiceConfigParser();
     }
 
     /**
@@ -187,6 +193,27 @@ protected int getGrpcPort(final ServiceInstance instance) {
         }
     }
 
+    /**
+     * Extracts the gRPC service config from the given service instances.
+     *
+     * @param instances The list of instances to extract the service config from.
+     * @return The gRPC service config or null.
+     */
+    protected String getServiceConfig(final List<ServiceInstance> instances) {
+        for (final ServiceInstance inst : instances) {
+            final Map<String, String> metadata = inst.getMetadata();
+            if (metadata == null || metadata.isEmpty()) {
+                continue;
+            }
+            final String metaValue = metadata.get(CLOUD_DISCOVERY_METADATA_SERVICE_CONFIG);
+            if (metaValue != null && !metaValue.isEmpty()) {
+                return metaValue;
+            }
+        }
+        return null;
+    }
+
+
     /**
      * Gets the attributes from the service instance for later use in a load balancer. Can be overwritten to convert
      * custom attributes.
@@ -314,11 +341,31 @@ private List<ServiceInstance> resolveInternal() {
                 return KEEP_PREVIOUS;
             }
 
+            final ResolutionResult.Builder result = ResolutionResult.newBuilder()
+                .setAddresses(toTargets(newInstanceList));
+
+            final String serviceConfig = getServiceConfig(newInstanceList);
+            if (serviceConfig != null) {
+                log.debug("Found service config for {}", getName());
+                log.trace("Service config for {}: {}", getName(), serviceConfig);
+                try {
+                    @SuppressWarnings("unchecked")
+                    Map<String, ?> parsedServiceConfig = GSON.fromJson(serviceConfig, Map.class);
+                    result.setServiceConfig(serviceConfigParser.parseServiceConfig(parsedServiceConfig));
+                } catch (JsonSyntaxException e) {
+                    result.setServiceConfig(
+                        ConfigOrError.fromError(
+                            Status.UNKNOWN
+                                .withDescription("Failed to parse grpc service config")
+                                .withCause(e)
+                        )
+                    );
+                }
+            }
+
             // Set new servers
             log.debug("Ready to update server list for {}", getName());
-            this.savedListener.onResult(ResolutionResult.newBuilder()
-                    .setAddresses(toTargets(newInstanceList))
-                    .build());
+            this.savedListener.onResult(result.build());
             log.info("Done updating server list for {}", getName());
             return newInstanceList;
         }

grpc-client-spring-boot-autoconfigure/src/test/java/net/devh/boot/grpc/client/nameresolver/DiscoveryClientNameResolverTest.java

@@ -0,0 +1,105 @@
+package net.devh.boot.grpc.client.nameresolver;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import io.grpc.NameResolver;
+import io.grpc.Status;
+import io.grpc.SynchronizationContext;
+import io.grpc.internal.AutoConfiguredLoadBalancerFactory;
+import io.grpc.internal.GrpcUtil;
+import io.grpc.internal.ScParser;
+import java.net.InetSocketAddress;
+import java.util.List;
+import java.util.Map;
+import net.devh.boot.grpc.common.util.GrpcUtils;
+import org.junit.jupiter.api.Test;
+import org.springframework.cloud.client.DefaultServiceInstance;
+import org.springframework.cloud.client.discovery.simple.SimpleDiscoveryClient;
+import org.springframework.cloud.client.discovery.simple.SimpleDiscoveryProperties;
+
+/**
+ * Test for {@link DiscoveryClientNameResolver}.
+ */
+public class DiscoveryClientNameResolverTest {
+
+    private final NameResolver.Args args = NameResolver.Args.newBuilder()
+        .setDefaultPort(1212)
+        .setProxyDetector(GrpcUtil.DEFAULT_PROXY_DETECTOR)
+        .setSynchronizationContext(
+            new SynchronizationContext((t, e) -> {
+                throw new AssertionError(e);
+            })
+        )
+        .setServiceConfigParser(
+            new ScParser(
+                true, 10, 10, new AutoConfiguredLoadBalancerFactory("pick_first")
+            )
+        )
+        .setOffloadExecutor(Runnable::run)
+        .build();
+
+    @Test
+    void testValidServiceConfig() {
+        var validServiceConfig = """
+            {
+              "loadBalancingConfig": [
+                {"round_robin": {}}
+              ],
+              "methodConfig": [
+                {
+                  "name": [{}],
+                  "retryPolicy": {
+                    "maxAttempts": 5,
+                    "initialBackoff": "0.05s",
+                    "maxBackoff": "1s",
+                    "backoffMultiplier": 2,
+                    "retryableStatusCodes": [
+                      "UNAVAILABLE",
+                      "ABORTED",
+                      "DATA_LOSS",
+                      "INTERNAL",
+                      "DEADLINE_EXCEEDED"
+                    ]
+                  },
+                  "timeout": "5s"
+                }
+              ]
+            }
+            """;
+        var listener = resolveServiceAndVerify("test1", validServiceConfig);
+        var serviceConf = listener.getResult().getServiceConfig();
+        assertThat(serviceConf).isNotNull();
+        assertThat(serviceConf.getConfig()).isNotNull();
+        assertThat(serviceConf.getError()).isNull();
+    }
+
+    @Test
+    void testBrokenServiceConfig() {
+        var listener = resolveServiceAndVerify("test2", "intentionally invalid service config");
+        var serviceConf = listener.getResult().getServiceConfig();
+        assertThat(serviceConf).isNotNull();
+        assertThat(serviceConf.getConfig()).isNull();
+        assertThat(serviceConf.getError()).extracting(Status::getCode).isEqualTo(Status.Code.UNKNOWN);
+    }
+
+    private TestableListener resolveServiceAndVerify(String serviceName, String serviceConfig) {
+        var props = new SimpleDiscoveryProperties();
+        var service = new DefaultServiceInstance(serviceName + "-1", serviceName, "127.0.0.1", 3322, false);
+        var meta = service.getMetadata();
+        meta.put(GrpcUtils.CLOUD_DISCOVERY_METADATA_PORT, "6688");
+        meta.put(GrpcUtils.CLOUD_DISCOVERY_METADATA_SERVICE_CONFIG, serviceConfig);
+        props.setInstances(Map.of(serviceName, List.of(service)));
+        var disco = new SimpleDiscoveryClient(props);
+        var dcnr = new DiscoveryClientNameResolver(serviceName, disco, args, null, null);
+
+        var listener = new TestableListener();
+        dcnr.start(listener);
+
+        assertThat(listener.isErrorWasSet()).isFalse();
+        assertThat(listener.isResultWasSet()).isTrue();
+        var addr = (InetSocketAddress) listener.getResult().getAddresses().get(0).getAddresses().get(0);
+        assertThat(addr.getPort()).isEqualTo(6688);
+        assertThat(addr.getHostString()).isEqualTo("127.0.0.1");
+        return listener;
+    }
+}

grpc-client-spring-boot-autoconfigure/src/test/java/net/devh/boot/grpc/client/nameresolver/TestableListener.java

@@ -0,0 +1,30 @@
+package net.devh.boot.grpc.client.nameresolver;
+
+import io.grpc.NameResolver;
+import io.grpc.Status;
+import lombok.Getter;
+
+@Getter
+public class TestableListener extends NameResolver.Listener2 {
+
+    private NameResolver.ResolutionResult result;
+
+    private Status error;
+
+    private boolean resultWasSet = false;
+
+    private boolean errorWasSet = false;
+
+    @Override
+    public void onResult(NameResolver.ResolutionResult resolutionResult) {
+        this.result = resolutionResult;
+        resultWasSet = true;
+    }
+
+    @Override
+    public void onError(Status error) {
+        this.error = error;
+        errorWasSet = true;
+    }
+
+}

grpc-common-spring-boot/src/main/java/net/devh/boot/grpc/common/util/GrpcUtils.java

@@ -40,6 +40,11 @@ public final class GrpcUtils {
      */
     public static final String CLOUD_DISCOVERY_METADATA_PORT = "gRPC_port";
 
+    /**
+     * The cloud discovery metadata key used to identify service config.
+     */
+    public static final String CLOUD_DISCOVERY_METADATA_SERVICE_CONFIG = "gRPC_service_config";
+
     /**
      * The constant for the grpc server port, -1 represents don't start an inter process server.
      */