Add grpc check example. (#306)

* Add grpc check example.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

* add missing package.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

rpc/example/go/health/main.go

@@ -1,11 +1,12 @@
 package main
 
 import (
+	"context"
 	"log"
+	"time"
 
-	"github.com/appleboy/gorush/rpc/proto"
+	"github.com/appleboy/gorush/rpc"
 
-	"golang.org/x/net/context"
 	"google.golang.org/grpc"
 )
 
@@ -21,10 +22,16 @@ func main() {
 	}
 	defer conn.Close()
 
-	c := proto.NewHealthClient(conn)
-	r, err := c.Check(context.Background(), &proto.HealthCheckRequest{})
-	if err != nil {
-		log.Fatalf("could not greet: %v", err)
+	client := rpc.NewGrpcHealthClient(conn)
+
+	for {
+		ok, err := client.Check(context.Background())
+		if !ok || err != nil {
+			log.Printf("can't connect grpc server: %v, code: %v\n", err, grpc.Code(err))
+		} else {
+			log.Println("connect the grpc server successfully")
+		}
+
+		<-time.After(time.Second)
 	}
-	log.Printf("Health: %d\n", r.GetStatus())
 }