Add config for setting up a jaeger opentracing reporter (#271)

* Add config for setting up a jaeger opentracing reporter

* Remove redundant comment

dendrite-config.yaml

@@ -91,3 +91,11 @@ listen:
     media_api: "localhost:7774"
     public_rooms_api: "localhost:7775"
     federation_sender: "localhost:7776"
+
+# The configuration for tracing the dendrite components.
+tracing:
+    # Config for the jaeger opentracing reporter.
+    # See https://godoc.org/github.com/uber/jaeger-client-go/config#Configuration
+    # for documtation.
+    jaeger:
+        disabled: true

src/github.com/matrix-org/dendrite/cmd/dendrite-client-api-server/main.go

@@ -51,6 +51,12 @@ func main() {
 		log.Fatalf("Invalid config file: %s", err)
 	}
 
+	closer, err := cfg.SetupTracing("DendriteClientAPI")
+	if err != nil {
+		log.WithError(err).Fatalf("Failed to start tracer")
+	}
+	defer closer.Close() // nolint: errcheck
+
 	queryAPI := api.NewRoomserverQueryAPIHTTP(cfg.RoomServerURL(), nil)
 	aliasAPI := api.NewRoomserverAliasAPIHTTP(cfg.RoomServerURL(), nil)
 	inputAPI := api.NewRoomserverInputAPIHTTP(cfg.RoomServerURL(), nil)

src/github.com/matrix-org/dendrite/cmd/dendrite-federation-api-server/main.go

@@ -50,6 +50,12 @@ func main() {
 		log.Fatalf("Invalid config file: %s", err)
 	}
 
+	closer, err := cfg.SetupTracing("DendriteFederationAPI")
+	if err != nil {
+		log.WithError(err).Fatalf("Failed to start tracer")
+	}
+	defer closer.Close() // nolint: errcheck
+
 	federation := gomatrixserverlib.NewFederationClient(
 		cfg.Matrix.ServerName, cfg.Matrix.KeyID, cfg.Matrix.PrivateKey,
 	)

src/github.com/matrix-org/dendrite/cmd/dendrite-federation-sender-server/main.go

@@ -47,6 +47,12 @@ func main() {
 		log.Fatalf("Invalid config file: %s", err)
 	}
 
+	closer, err := cfg.SetupTracing("DendriteFederationSender")
+	if err != nil {
+		log.WithError(err).Fatalf("Failed to start tracer")
+	}
+	defer closer.Close() // nolint: errcheck
+
 	kafkaConsumer, err := sarama.NewConsumer(cfg.Kafka.Addresses, nil)
 	if err != nil {
 		log.WithFields(log.Fields{

src/github.com/matrix-org/dendrite/cmd/dendrite-media-api-server/main.go

@@ -48,6 +48,12 @@ func main() {
 		log.Fatalf("Invalid config file: %s", err)
 	}
 
+	closer, err := cfg.SetupTracing("DendriteMediaAPI")
+	if err != nil {
+		log.WithError(err).Fatalf("Failed to start tracer")
+	}
+	defer closer.Close() // nolint: errcheck
+
 	db, err := storage.Open(string(cfg.Database.MediaAPI))
 	if err != nil {
 		log.WithError(err).Panic("Failed to open database")

src/github.com/matrix-org/dendrite/cmd/dendrite-monolith-server/main.go

@@ -83,6 +83,12 @@ func main() {
 		log.Fatalf("Invalid config file: %s", err)
 	}
 
+	closer, err := cfg.SetupTracing("DendriteMonolith")
+	if err != nil {
+		log.WithError(err).Fatalf("Failed to start tracer")
+	}
+	defer closer.Close() // nolint: errcheck
+
 	m := newMonolith(cfg)
 	m.setupDatabases()
 	m.setupFederation()

src/github.com/matrix-org/dendrite/cmd/dendrite-public-rooms-api-server/main.go

@@ -47,6 +47,12 @@ func main() {
 		log.Fatalf("Invalid config file: %s", err)
 	}
 
+	closer, err := cfg.SetupTracing("DendritePublicRoomsAPI")
+	if err != nil {
+		log.WithError(err).Fatalf("Failed to start tracer")
+	}
+	defer closer.Close() // nolint: errcheck
+
 	queryAPI := api.NewRoomserverQueryAPIHTTP(cfg.RoomServerURL(), nil)
 
 	db, err := storage.NewPublicRoomsServerDatabase(string(cfg.Database.PublicRoomsAPI))

src/github.com/matrix-org/dendrite/cmd/dendrite-room-server/main.go

@@ -49,6 +49,12 @@ func main() {
 		log.Fatalf("Invalid config file: %s", err)
 	}
 
+	closer, err := cfg.SetupTracing("DendriteRoomServer")
+	if err != nil {
+		log.WithError(err).Fatalf("Failed to start tracer")
+	}
+	defer closer.Close() // nolint: errcheck
+
 	db, err := storage.Open(string(cfg.Database.RoomServer))
 	if err != nil {
 		panic(err)

src/github.com/matrix-org/dendrite/cmd/dendrite-sync-api-server/main.go

@@ -51,6 +51,12 @@ func main() {
 		log.Fatalf("Invalid config file: %s", err)
 	}
 
+	closer, err := cfg.SetupTracing("DendriteSyncAPI")
+	if err != nil {
+		log.WithError(err).Fatalf("Failed to start tracer")
+	}
+	defer closer.Close() // nolint: errcheck
+
 	queryAPI := api.NewRoomserverQueryAPIHTTP(cfg.RoomServerURL(), nil)
 
 	db, err := storage.NewSyncServerDatabase(string(cfg.Database.SyncAPI))

src/github.com/matrix-org/dendrite/common/config/config.go

@@ -19,14 +19,19 @@ import (
 	"crypto/sha256"
 	"encoding/pem"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"path/filepath"
 	"strings"
 	"time"
 
+	"github.com/Sirupsen/logrus"
 	"github.com/matrix-org/gomatrixserverlib"
 	"golang.org/x/crypto/ed25519"
 	"gopkg.in/yaml.v2"
+
+	jaegerconfig "github.com/uber/jaeger-client-go/config"
+	jaegermetrics "github.com/uber/jaeger-lib/metrics"
 )
 
 // Version is the current version of the config format.
@@ -156,6 +161,12 @@ type Dendrite struct {
 		FederationSender Address `yaml:"federation_sender"`
 		PublicRoomsAPI   Address `yaml:"public_rooms_api"`
 	} `yaml:"listen"`
+
+	// The config for tracing the dendrite servers.
+	Tracing struct {
+		// The config for the jaeger opentracing reporter.
+		Jaeger jaegerconfig.Configuration `yaml:"jaeger"`
+	}
 }
 
 // A Path on the filesystem.
@@ -429,3 +440,25 @@ func (config *Dendrite) RoomServerURL() string {
 	// internet for an internal API.
 	return "http://" + string(config.Listen.RoomServer)
 }
+
+// SetupTracing configures the opentracing using the supplied configuration.
+func (config *Dendrite) SetupTracing(serviceName string) (closer io.Closer, err error) {
+	return config.Tracing.Jaeger.InitGlobalTracer(
+		serviceName,
+		jaegerconfig.Logger(logrusLogger{logrus.StandardLogger()}),
+		jaegerconfig.Metrics(jaegermetrics.NullFactory),
+	)
+}
+
+// logrusLogger is a small wrapper that implements jaeger.Logger using logrus.
+type logrusLogger struct {
+	l *logrus.Logger
+}
+
+func (l logrusLogger) Error(msg string) {
+	l.l.Error(msg)
+}
+
+func (l logrusLogger) Infof(msg string, args ...interface{}) {
+	l.l.Infof(msg, args...)
+}