swarm: integrate OpenTracing; propagate ctx to internal APIs (#17169)

* swarm: propagate ctx, enable opentracing

* swarm/tracing: log error when tracing is misconfigured

swarm/tracing/tracing.go

@@ -0,0 +1,103 @@
+package tracing
+
+import (
+	"io"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/ethereum/go-ethereum/log"
+	jaeger "github.com/uber/jaeger-client-go"
+	jaegercfg "github.com/uber/jaeger-client-go/config"
+	jaegerlog "github.com/uber/jaeger-client-go/log"
+	cli "gopkg.in/urfave/cli.v1"
+)
+
+var Enabled bool = false
+
+// TracingEnabledFlag is the CLI flag name to use to enable trace collections.
+const TracingEnabledFlag = "tracing"
+
+var (
+	Closer io.Closer
+)
+
+var (
+	TracingFlag = cli.BoolFlag{
+		Name:  TracingEnabledFlag,
+		Usage: "Enable tracing",
+	}
+	TracingEndpointFlag = cli.StringFlag{
+		Name:  "tracing.endpoint",
+		Usage: "Tracing endpoint",
+		Value: "0.0.0.0:6831",
+	}
+	TracingSvcFlag = cli.StringFlag{
+		Name:  "tracing.svc",
+		Usage: "Tracing service name",
+		Value: "swarm",
+	}
+)
+
+// Flags holds all command-line flags required for tracing collection.
+var Flags = []cli.Flag{
+	TracingFlag,
+	TracingEndpointFlag,
+	TracingSvcFlag,
+}
+
+// Init enables or disables the open tracing system.
+func init() {
+	for _, arg := range os.Args {
+		if flag := strings.TrimLeft(arg, "-"); flag == TracingEnabledFlag {
+			Enabled = true
+		}
+	}
+}
+
+func Setup(ctx *cli.Context) {
+	if Enabled {
+		log.Info("Enabling opentracing")
+		var (
+			endpoint = ctx.GlobalString(TracingEndpointFlag.Name)
+			svc      = ctx.GlobalString(TracingSvcFlag.Name)
+		)
+
+		Closer = initTracer(endpoint, svc)
+	}
+}
+
+func initTracer(endpoint, svc string) (closer io.Closer) {
+	// Sample configuration for testing. Use constant sampling to sample every trace
+	// and enable LogSpan to log every span via configured Logger.
+	cfg := jaegercfg.Configuration{
+		Sampler: &jaegercfg.SamplerConfig{
+			Type:  jaeger.SamplerTypeConst,
+			Param: 1,
+		},
+		Reporter: &jaegercfg.ReporterConfig{
+			LogSpans:            true,
+			BufferFlushInterval: 1 * time.Second,
+			LocalAgentHostPort:  endpoint,
+		},
+	}
+
+	// Example logger and metrics factory. Use github.com/uber/jaeger-client-go/log
+	// and github.com/uber/jaeger-lib/metrics respectively to bind to real logging and metrics
+	// frameworks.
+	jLogger := jaegerlog.StdLogger
+	//jMetricsFactory := metrics.NullFactory
+
+	// Initialize tracer with a logger and a metrics factory
+	closer, err := cfg.InitGlobalTracer(
+		svc,
+		jaegercfg.Logger(jLogger),
+		//jaegercfg.Metrics(jMetricsFactory),
+		//jaegercfg.Observer(rpcmetrics.NewObserver(jMetricsFactory, rpcmetrics.DefaultNameNormalizer)),
+	)
+	if err != nil {
+		log.Error("Could not initialize Jaeger tracer", "err", err)
+	}
+
+	return closer
+}