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// Copyright (c) The go-grpc-middleware Authors.
// Licensed under the Apache License 2.0.
package main
import (
"context"
"fmt"
"net"
"net/http"
"os"
"runtime/debug"
"syscall"
"github.com/go-kit/log"
"github.com/go-kit/log/level"
grpcprom "github.com/grpc-ecosystem/go-grpc-middleware/providers/prometheus"
"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors"
"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/auth"
"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/logging"
"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/recovery"
"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/selector"
"github.com/grpc-ecosystem/go-grpc-middleware/v2/testing/testpb"
"github.com/oklog/run"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promauto"
"github.com/prometheus/client_golang/prometheus/promhttp"
"go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc"
"go.opentelemetry.io/otel"
stdout "go.opentelemetry.io/otel/exporters/stdout/stdouttrace"
"go.opentelemetry.io/otel/propagation"
sdktrace "go.opentelemetry.io/otel/sdk/trace"
"go.opentelemetry.io/otel/trace"
"google.golang.org/grpc"
"google.golang.org/grpc/codes"
healthpb "google.golang.org/grpc/health/grpc_health_v1"
"google.golang.org/grpc/status"
)
const (
component = "grpc-example"
grpcAddr = ":8080"
httpAddr = ":8081"
)
// interceptorLogger adapts go-kit logger to interceptor logger.
// This code is simple enough to be copied and not imported.
func interceptorLogger(l log.Logger) logging.Logger {
return logging.LoggerFunc(func(_ context.Context, lvl logging.Level, msg string, fields ...any) {
largs := append([]any{"msg", msg}, fields...)
switch lvl {
case logging.LevelDebug:
_ = level.Debug(l).Log(largs...)
case logging.LevelInfo:
_ = level.Info(l).Log(largs...)
case logging.LevelWarn:
_ = level.Warn(l).Log(largs...)
case logging.LevelError:
_ = level.Error(l).Log(largs...)
default:
panic(fmt.Sprintf("unknown level %v", lvl))
}
})
}
func main() {
// Setup logging.
logger := log.NewLogfmtLogger(os.Stderr)
rpcLogger := log.With(logger, "service", "gRPC/server", "component", component)
logTraceID := func(ctx context.Context) logging.Fields {
if span := trace.SpanContextFromContext(ctx); span.IsSampled() {
return logging.Fields{"traceID", span.TraceID().String()}
}
return nil
}
// Setup metrics.
srvMetrics := grpcprom.NewServerMetrics(
grpcprom.WithServerHandlingTimeHistogram(
grpcprom.WithHistogramBuckets([]float64{0.001, 0.01, 0.1, 0.3, 0.6, 1, 3, 6, 9, 20, 30, 60, 90, 120}),
),
)
reg := prometheus.NewRegistry()
reg.MustRegister(srvMetrics)
exemplarFromContext := func(ctx context.Context) prometheus.Labels {
if span := trace.SpanContextFromContext(ctx); span.IsSampled() {
return prometheus.Labels{"traceID": span.TraceID().String()}
}
return nil
}
// Set up OTLP tracing (stdout for debug).
exporter, err := stdout.New(stdout.WithPrettyPrint())
if err != nil {
level.Error(logger).Log("err", err)
os.Exit(1)
}
tp := sdktrace.NewTracerProvider(
sdktrace.WithSampler(sdktrace.AlwaysSample()),
sdktrace.WithBatcher(exporter),
)
otel.SetTracerProvider(tp)
otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(propagation.TraceContext{}, propagation.Baggage{}))
defer func() { _ = exporter.Shutdown(context.Background()) }()
// Setup custom auth.
authFn := func(ctx context.Context) (context.Context, error) {
token, err := auth.AuthFromMD(ctx, "bearer")
if err != nil {
return nil, err
}
// TODO: This is example only, perform proper Oauth/OIDC verification!
if token != "yolo" {
return nil, status.Error(codes.Unauthenticated, "invalid auth token")
}
// NOTE: You can also pass the token in the context for further interceptors or gRPC service code.
return ctx, nil
}
// Setup auth matcher.
allButHealthZ := func(ctx context.Context, callMeta interceptors.CallMeta) bool {
return healthpb.Health_ServiceDesc.ServiceName != callMeta.Service
}
// Setup metric for panic recoveries.
panicsTotal := promauto.With(reg).NewCounter(prometheus.CounterOpts{
Name: "grpc_req_panics_recovered_total",
Help: "Total number of gRPC requests recovered from internal panic.",
})
grpcPanicRecoveryHandler := func(p any) (err error) {
panicsTotal.Inc()
level.Error(rpcLogger).Log("msg", "recovered from panic", "panic", p, "stack", debug.Stack())
return status.Errorf(codes.Internal, "%s", p)
}
grpcSrv := grpc.NewServer(
grpc.ChainUnaryInterceptor(
// Order matters e.g. tracing interceptor have to create span first for the later exemplars to work.
otelgrpc.UnaryServerInterceptor(),
srvMetrics.UnaryServerInterceptor(grpcprom.WithExemplarFromContext(exemplarFromContext)),
logging.UnaryServerInterceptor(interceptorLogger(rpcLogger), logging.WithFieldsFromContext(logTraceID)),
selector.UnaryServerInterceptor(auth.UnaryServerInterceptor(authFn), selector.MatchFunc(allButHealthZ)),
recovery.UnaryServerInterceptor(recovery.WithRecoveryHandler(grpcPanicRecoveryHandler)),
),
grpc.ChainStreamInterceptor(
otelgrpc.StreamServerInterceptor(),
srvMetrics.StreamServerInterceptor(grpcprom.WithExemplarFromContext(exemplarFromContext)),
logging.StreamServerInterceptor(interceptorLogger(rpcLogger), logging.WithFieldsFromContext(logTraceID)),
selector.StreamServerInterceptor(auth.StreamServerInterceptor(authFn), selector.MatchFunc(allButHealthZ)),
recovery.StreamServerInterceptor(recovery.WithRecoveryHandler(grpcPanicRecoveryHandler)),
),
)
t := &testpb.TestPingService{}
testpb.RegisterTestServiceServer(grpcSrv, t)
srvMetrics.InitializeMetrics(grpcSrv)
g := &run.Group{}
g.Add(func() error {
l, err := net.Listen("tcp", grpcAddr)
if err != nil {
return err
}
level.Info(logger).Log("msg", "starting gRPC server", "addr", l.Addr().String())
return grpcSrv.Serve(l)
}, func(err error) {
grpcSrv.GracefulStop()
grpcSrv.Stop()
})
httpSrv := &http.Server{Addr: httpAddr}
g.Add(func() error {
m := http.NewServeMux()
// Create HTTP handler for Prometheus metrics.
m.Handle("/metrics", promhttp.HandlerFor(
reg,
promhttp.HandlerOpts{
// Opt into OpenMetrics e.g. to support exemplars.
EnableOpenMetrics: true,
},
))
httpSrv.Handler = m
level.Info(logger).Log("msg", "starting HTTP server", "addr", httpSrv.Addr)
return httpSrv.ListenAndServe()
}, func(error) {
if err := httpSrv.Close(); err != nil {
level.Error(logger).Log("msg", "failed to stop web server", "err", err)
}
})
g.Add(run.SignalHandler(context.Background(), syscall.SIGINT, syscall.SIGTERM))
if err := g.Run(); err != nil {
level.Error(logger).Log("err", err)
os.Exit(1)
}
}
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