Add gRPC reverse proxy server example

examples/grpc/build.gradle

@@ -16,6 +16,7 @@ dependencies {
     testImplementation libs.awaitility
     testImplementation libs.junit5.jupiter.api
     testImplementation libs.protobuf.java.util
+    testImplementation libs.testcontainers.junit.jupiter
 }
 
 application {

examples/grpc/envoy/envoy.yaml

@@ -0,0 +1,45 @@
+static_resources:
+  listeners:
+    - name: listener_0
+      address:
+        socket_address:
+          address: 0.0.0.0
+          port_value: 9090
+      filter_chains:
+        - filters:
+            - name: envoy.filters.network.http_connection_manager
+              typed_config:
+                "@type": type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager
+                stat_prefix: ingress_http
+                codec_type: AUTO
+                route_config:
+                  name: local_route
+                  virtual_hosts:
+                    - name: local_service
+                      domains: ["*"]
+                      routes:
+                        - match:
+                            prefix: "/"
+                          route:
+                            cluster: grpc_service
+                            timeout: 0s
+                            idle_timeout: 0s
+                http_filters:
+                  - name: envoy.filters.http.router
+                    typed_config:
+                      "@type": type.googleapis.com/envoy.extensions.filters.http.router.v3.Router
+  clusters:
+    - name: grpc_service
+      connect_timeout: 1s
+      type: STRICT_DNS
+      lb_policy: round_robin
+      http2_protocol_options: {}
+      load_assignment:
+        cluster_name: grpc_service
+        endpoints:
+          - lb_endpoints:
+              - endpoint:
+                  address:
+                    socket_address:
+                      address: host.docker.internal
+                      port_value: 18080

examples/grpc/src/test/java/example/armeria/grpc/GrpcReverseProxyServerTest.java

@@ -0,0 +1,63 @@
+package example.armeria.grpc;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.testcontainers.containers.BindMode;
+import org.testcontainers.containers.GenericContainer;
+import org.testcontainers.junit.jupiter.Container;
+
+import com.linecorp.armeria.client.WebClient;
+import com.linecorp.armeria.client.grpc.GrpcClients;
+import com.linecorp.armeria.server.Server;
+import com.linecorp.armeria.server.grpc.GrpcService;
+
+import example.armeria.grpc.Hello.HelloReply;
+import example.armeria.grpc.Hello.HelloRequest;
+
+class GrpcReverseProxyServerTest {
+
+    private static Server server;
+
+    @Container
+    private static GenericContainer<?> envoy = new GenericContainer<>("envoyproxy/envoy:v1.22.0")
+            .withExposedPorts(9090)
+            .withFileSystemBind("./envoy/envoy.yaml", "/etc/envoy/envoy.yaml", BindMode.READ_WRITE);
+
+    @BeforeAll
+    static void startServer() {
+        server = Server.builder()
+                .http(18080)
+                .service(GrpcService.builder()
+                        .addService(new HelloServiceImpl())
+                        .build())
+                .build();
+        server.start().join();
+        envoy.start();
+    }
+
+    @AfterAll
+    static void stopServer() {
+        server.stop().join();
+        envoy.stop();
+    }
+
+    @Test
+    void reverseProxy() {
+
+        // given
+        final String envoyAddress = "http://" + envoy.getHost() + ":" + envoy.getMappedPort(9090);
+
+        final WebClient client = WebClient.of(envoyAddress);
+        final HelloServiceGrpc.HelloServiceBlockingStub helloService = GrpcClients.builder(client.uri())
+                .build(HelloServiceGrpc.HelloServiceBlockingStub.class);
+
+        // when
+        final HelloReply reply = helloService.hello(HelloRequest.newBuilder().setName("Armeria").build());
+
+        // then
+        assertThat(reply.getMessage()).isEqualTo("Hello, Armeria!");
+    }
+}