snapshot of https://github.com/grpc/grpc-go.git (master, 2026-09-15; blobs > 131072B omitted)

examples/features/health/client/main.go

@@ -0,0 +1,88 @@
+/*
+ *
+ * Copyright 2020 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Binary client demonstrates how to check and observe gRPC server health using
+// the health library.
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"log"
+	"time"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+	pb "google.golang.org/grpc/examples/features/proto/echo"
+	_ "google.golang.org/grpc/health" // REQUIRED to enable health checks
+	"google.golang.org/grpc/resolver"
+	"google.golang.org/grpc/resolver/manual"
+)
+
+const serviceConfig = `{
+	"loadBalancingPolicy": "round_robin",
+	"healthCheckConfig": {
+		"serviceName": ""
+	}
+}`
+
+func callUnaryEcho(c pb.EchoClient) {
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+	defer cancel()
+	r, err := c.UnaryEcho(ctx, &pb.EchoRequest{})
+	if err != nil {
+		fmt.Println("UnaryEcho: _, ", err)
+	} else {
+		fmt.Println("UnaryEcho: ", r.GetMessage())
+	}
+}
+
+func main() {
+	flag.Parse()
+
+	r := manual.NewBuilderWithScheme("whatever")
+	r.InitialState(resolver.State{
+		Addresses: []resolver.Address{
+			{Addr: "localhost:50051"},
+			{Addr: "localhost:50052"},
+		},
+	})
+
+	address := fmt.Sprintf("%s:///unused", r.Scheme())
+
+	options := []grpc.DialOption{
+		grpc.WithTransportCredentials(insecure.NewCredentials()),
+		grpc.WithResolvers(r),
+		// google.golang.org/grpc/health must also be imported
+		grpc.WithDefaultServiceConfig(serviceConfig),
+	}
+
+	conn, err := grpc.NewClient(address, options...)
+	if err != nil {
+		log.Fatalf("grpc.NewClient(%q): %v", address, err)
+	}
+	defer conn.Close()
+
+	echoClient := pb.NewEchoClient(conn)
+
+	for {
+		callUnaryEcho(echoClient)
+		time.Sleep(time.Second)
+	}
+}