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April 15, 2019 00:12
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// author: Gary A. Stafford | |
// site: https://programmaticponderings.com | |
// license: MIT License | |
// purpose: Service A - gRPC/Protobuf | |
package main | |
import ( | |
"context" | |
"github.com/banzaicloud/logrus-runtime-formatter" | |
"github.com/google/uuid" | |
"github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing" | |
ot "github.com/opentracing/opentracing-go" | |
log "github.com/sirupsen/logrus" | |
"google.golang.org/grpc" | |
"google.golang.org/grpc/metadata" | |
"net" | |
"os" | |
"time" | |
pb "github.com/garystafford/pb-greeting" | |
) | |
const ( | |
port = ":50051" | |
) | |
type greetingServiceServer struct { | |
} | |
var ( | |
greetings []*pb.Greeting | |
) | |
func (s *greetingServiceServer) Greeting(ctx context.Context, req *pb.GreetingRequest) (*pb.GreetingResponse, error) { | |
greetings = nil | |
tmpGreeting := pb.Greeting{ | |
Id: uuid.New().String(), | |
Service: "Service-A", | |
Message: "Hello, from Service-A!", | |
Created: time.Now().Local().String(), | |
} | |
greetings = append(greetings, &tmpGreeting) | |
CallGrpcService(ctx, "service-b:50051") | |
CallGrpcService(ctx, "service-c:50051") | |
return &pb.GreetingResponse{ | |
Greeting: greetings, | |
}, nil | |
} | |
func CallGrpcService(ctx context.Context, address string) { | |
conn, err := createGRPCConn(ctx, address) | |
if err != nil { | |
log.Fatalf("did not connect: %v", err) | |
} | |
defer conn.Close() | |
headersIn, _ := metadata.FromIncomingContext(ctx) | |
log.Infof("headersIn: %s", headersIn) | |
client := pb.NewGreetingServiceClient(conn) | |
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second) | |
ctx = metadata.NewOutgoingContext(context.Background(), headersIn) | |
defer cancel() | |
req := pb.GreetingRequest{} | |
greeting, err := client.Greeting(ctx, &req) | |
log.Info(greeting.GetGreeting()) | |
if err != nil { | |
log.Fatalf("did not connect: %v", err) | |
} | |
for _, greeting := range greeting.GetGreeting() { | |
greetings = append(greetings, greeting) | |
} | |
} | |
func createGRPCConn(ctx context.Context, addr string) (*grpc.ClientConn, error) { | |
//https://aspenmesh.io/2018/04/tracing-grpc-with-istio/ | |
var opts []grpc.DialOption | |
opts = append(opts, grpc.WithStreamInterceptor( | |
grpc_opentracing.StreamClientInterceptor( | |
grpc_opentracing.WithTracer(ot.GlobalTracer())))) | |
opts = append(opts, grpc.WithUnaryInterceptor( | |
grpc_opentracing.UnaryClientInterceptor( | |
grpc_opentracing.WithTracer(ot.GlobalTracer())))) | |
opts = append(opts, grpc.WithInsecure()) | |
conn, err := grpc.DialContext(ctx, addr, opts...) | |
if err != nil { | |
log.Fatalf("Failed to connect to application addr: ", err) | |
return nil, err | |
} | |
return conn, nil | |
} | |
func getEnv(key, fallback string) string { | |
if value, ok := os.LookupEnv(key); ok { | |
return value | |
} | |
return fallback | |
} | |
func init() { | |
formatter := runtime.Formatter{ChildFormatter: &log.JSONFormatter{}} | |
formatter.Line = true | |
log.SetFormatter(&formatter) | |
log.SetOutput(os.Stdout) | |
level, err := log.ParseLevel(getEnv("LOG_LEVEL", "info")) | |
if err != nil { | |
log.Error(err) | |
} | |
log.SetLevel(level) | |
} | |
func main() { | |
lis, err := net.Listen("tcp", port) | |
if err != nil { | |
log.Fatalf("failed to listen: %v", err) | |
} | |
s := grpc.NewServer() | |
pb.RegisterGreetingServiceServer(s, &greetingServiceServer{}) | |
log.Fatal(s.Serve(lis)) | |
} |
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