1 /*
2 *
3 * Copyright 2021 gRPC authors.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 */
18
19 // Explicitly define HAVE_ABSEIL to avoid conflict with OTel's Abseil
20 // version. Refer
21 // https://github.com/open-telemetry/opentelemetry-cpp/issues/1042.
22 #ifndef HAVE_ABSEIL
23 #define HAVE_ABSEIL
24 #endif
25
26 #include <grpcpp/ext/otel_plugin.h>
27 #include <grpcpp/grpcpp.h>
28
29 #include <condition_variable>
30 #include <mutex>
31 #include <string>
32
33 #include "absl/flags/flag.h"
34 #include "absl/flags/parse.h"
35 #include "opentelemetry/exporters/prometheus/exporter_factory.h"
36 #include "opentelemetry/exporters/prometheus/exporter_options.h"
37 #include "opentelemetry/sdk/metrics/meter_provider.h"
38
39 #ifdef BAZEL_BUILD
40 #include "examples/cpp/otel/codelab/util.h"
41 #include "examples/protos/helloworld.grpc.pb.h"
42 #else
43 #include "helloworld.grpc.pb.h"
44 #include "util.h"
45 #endif
46
47 ABSL_FLAG(std::string, target, "localhost:50051", "Server address");
48 ABSL_FLAG(std::string, prometheus_endpoint, "localhost:9465",
49 "Prometheus exporter endpoint");
50
51 namespace {
52
53 using grpc::Channel;
54 using grpc::ClientContext;
55 using grpc::Status;
56 using helloworld::Greeter;
57 using helloworld::HelloReply;
58 using helloworld::HelloRequest;
59
60 class GreeterClient {
61 public:
GreeterClient(std::shared_ptr<Channel> channel)62 GreeterClient(std::shared_ptr<Channel> channel)
63 : stub_(Greeter::NewStub(channel)) {}
64
65 // Assembles the client's payload, sends it and presents the response back
66 // from the server.
SayHello(const std::string & user)67 std::string SayHello(const std::string& user) {
68 // Data we are sending to the server.
69 HelloRequest request;
70 request.set_name(user);
71
72 // Container for the data we expect from the server.
73 HelloReply reply;
74
75 // Context for the client. It could be used to convey extra information to
76 // the server and/or tweak certain RPC behaviors.
77 ClientContext context;
78
79 // The actual RPC.
80 std::mutex mu;
81 std::condition_variable cv;
82 bool done = false;
83 Status status;
84 stub_->async()->SayHello(&context, &request, &reply,
85 [&mu, &cv, &done, &status](Status s) {
86 status = std::move(s);
87 std::lock_guard<std::mutex> lock(mu);
88 done = true;
89 cv.notify_one();
90 });
91
92 std::unique_lock<std::mutex> lock(mu);
93 while (!done) {
94 cv.wait(lock);
95 }
96
97 // Act upon its status.
98 if (status.ok()) {
99 return reply.message();
100 } else {
101 std::cout << status.error_code() << ": " << status.error_message()
102 << std::endl;
103 return "RPC failed";
104 }
105 }
106
107 private:
108 std::unique_ptr<Greeter::Stub> stub_;
109 };
110
RunClient(const std::string & target_str)111 void RunClient(const std::string& target_str) {
112 // Instantiate the client. It requires a channel, out of which the actual RPCs
113 // are created. This channel models a connection to an endpoint specified by
114 // the argument "--target=" which is the only expected argument.
115 grpc::ChannelArguments args;
116 // Continuously send RPCs every second.
117 while (true) {
118 GreeterClient greeter(grpc::CreateCustomChannel(
119 target_str, grpc::InsecureChannelCredentials(), args));
120 std::string user("world");
121 std::string reply = greeter.SayHello(user);
122 std::cout << "Greeter received: " << reply << std::endl;
123 std::this_thread::sleep_for(std::chrono::seconds(1));
124 }
125 }
126
127 } // namespace
128
main(int argc,char ** argv)129 int main(int argc, char** argv) {
130 absl::ParseCommandLine(argc, argv);
131 // Register a global gRPC OpenTelemetry plugin configured with a prometheus
132 // exporter.
133 opentelemetry::exporter::metrics::PrometheusExporterOptions opts;
134 opts.url = absl::GetFlag(FLAGS_prometheus_endpoint);
135 auto prometheus_exporter =
136 opentelemetry::exporter::metrics::PrometheusExporterFactory::Create(opts);
137 auto meter_provider =
138 std::make_shared<opentelemetry::sdk::metrics::MeterProvider>();
139 // The default histogram boundaries are not granular enough for RPCs. Override
140 // the "grpc.client.attempt.duration" view as recommended by
141 // https://github.com/grpc/proposal/blob/master/A66-otel-stats.md.
142 AddLatencyView(meter_provider.get(), "grpc.client.attempt.duration", "s");
143 meter_provider->AddMetricReader(std::move(prometheus_exporter));
144 auto status = grpc::OpenTelemetryPluginBuilder()
145 .SetMeterProvider(std::move(meter_provider))
146 .BuildAndRegisterGlobal();
147 if (!status.ok()) {
148 std::cerr << "Failed to register gRPC OpenTelemetry Plugin: "
149 << status.ToString() << std::endl;
150 return static_cast<int>(status.code());
151 }
152
153 // Continuously send RPCs.
154 RunClient(absl::GetFlag(FLAGS_target));
155
156 return 0;
157 }
158