/
client.go
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/
client.go
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// Copyright 2020 Google LLC
//
// 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
//
// https://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.
// Package client is a small tool to query the streaming gRPC endpoint.
package main
import (
"context"
"crypto/tls"
"flag"
"fmt"
"io"
"log"
"os"
"time"
"github.com/golang/protobuf/ptypes"
"google.golang.org/grpc"
"google.golang.org/grpc/credentials"
pb "github.com/GoogleCloudPlatform/golang-samples/run/grpc-server-streaming/pkg/api/v1"
)
var (
logger = log.New(os.Stdout, "", 0)
serverAddr = flag.String("server", "", "Server address (host:port)")
serverHost = flag.String("server-host", "", "Host name to which server IP should resolve")
insecure = flag.Bool("insecure", false, "Skip SSL validation? [false]")
skipVerify = flag.Bool("skip-verify", false, "Skip server hostname verification in SSL validation [false]")
duration = flag.Uint("duration", 10, "duration (in seconds) to stream the time from the server for")
)
func init() {
flag.Parse()
log.SetFlags(log.Flags() ^ log.Ltime ^ log.Ldate)
}
func main() {
var opts []grpc.DialOption
if *serverAddr == "" {
log.Fatal("-server is empty")
}
if *serverHost != "" {
opts = append(opts, grpc.WithAuthority(*serverHost))
}
if *insecure {
opts = append(opts, grpc.WithInsecure())
} else {
cred := credentials.NewTLS(&tls.Config{
InsecureSkipVerify: *skipVerify,
})
opts = append(opts, grpc.WithTransportCredentials(cred))
}
conn, err := grpc.Dial(*serverAddr, opts...)
if err != nil {
logger.Printf("failed to dial server %s: %v", *serverAddr, err)
}
defer conn.Close()
client := pb.NewTimeServiceClient(conn)
if err := streamTime(client, *duration); err != nil {
log.Fatal(err)
}
}
func streamTime(client pb.TimeServiceClient, duration uint) error {
ctx := context.Background()
resp, err := client.StreamTime(ctx, &pb.Request{
DurationSecs: uint32(duration)})
if err != nil {
return fmt.Errorf("StreamTime rpc failed: %w", err)
}
log.Print("rpc established to timeserver, starting to stream")
for {
msg, err := resp.Recv()
if err == io.EOF {
log.Printf("end of stream")
return nil
} else if err != nil {
return fmt.Errorf("error receiving message: %w", err)
}
ts, err := ptypes.Timestamp(msg.GetCurrentTime())
if err != nil {
return fmt.Errorf("failed to parse timestamp %v: %w", msg.GetCurrentTime(), err)
}
log.Printf("received message: current_timestamp: %v", ts.Format(time.RFC3339))
}
}