// ExtractInboundSpan is a higher level version of extractInboundSpan().
// If the lower-level attempt to create a span from incoming request was
// successful (e.g. when then Tracer supports Zipkin-style trace IDs),
// then the application headers are only used to read the Baggage and add
// it to the existing span. Otherwise, the standard OpenTracing API supported
// by all tracers is used to deserialize the tracing context from the
// application headers and start a new server-side span.
// Once the span is started, it is wrapped in a new Context, which is returned.
func ExtractInboundSpan(ctx context.Context, call *InboundCall, headers map[string]string, tracer opentracing.Tracer) context.Context {
var span = call.Response().span
if span != nil {
if headers != nil {
// extract SpanContext from headers, but do not start another span with it,
// just get the baggage and copy to the already created span
carrier := tracingHeadersCarrier(headers)
if sc, err := tracer.Extract(opentracing.TextMap, carrier); err == nil {
sc.ForeachBaggageItem(func(k, v string) bool {
span.SetBaggageItem(k, v)
return true
})
}
carrier.RemoveTracingKeys()
}
} else {
var parent opentracing.SpanContext
if headers != nil {
carrier := tracingHeadersCarrier(headers)
if p, err := tracer.Extract(opentracing.TextMap, carrier); err == nil {
parent = p
}
carrier.RemoveTracingKeys()
}
span = tracer.StartSpan(call.MethodString(), ext.RPCServerOption(parent))
ext.PeerService.Set(span, call.CallerName())
span.SetTag("as", string(call.Format()))
call.conn.setPeerHostPort(span)
call.Response().span = span
}
return opentracing.ContextWithSpan(ctx, span)
}
func TestRPCServerOption(t *testing.T) {
tracer := mocktracer.New()
parent := tracer.StartSpan("my-trace")
parent.SetBaggageItem("bag", "gage")
carrier := opentracing.HTTPHeadersCarrier{}
err := tracer.Inject(parent.Context(), opentracing.HTTPHeaders, carrier)
if err != nil {
t.Fatal(err)
}
parCtx, err := tracer.Extract(opentracing.HTTPHeaders, carrier)
if err != nil {
t.Fatal(err)
}
tracer.StartSpan("my-child", ext.RPCServerOption(parCtx)).Finish()
rawSpan := tracer.FinishedSpans()[0]
assert.Equal(t, map[string]interface{}{
"span.kind": ext.SpanKindRPCServerEnum,
}, rawSpan.Tags())
assert.Equal(t, map[string]string{
"bag": "gage",
}, rawSpan.Context().(mocktracer.MockSpanContext).Baggage)
}
// FromGRPCRequest returns a grpc RequestFunc that tries to join with an
// OpenTracing trace found in `req` and starts a new Span called
// `operationName` accordingly. If no trace could be found in `req`, the Span
// will be a trace root. The Span is incorporated in the returned Context and
// can be retrieved with opentracing.SpanFromContext(ctx).
func FromGRPCRequest(tracer opentracing.Tracer, operationName string, logger log.Logger) func(ctx context.Context, md *metadata.MD) context.Context {
return func(ctx context.Context, md *metadata.MD) context.Context {
var span opentracing.Span
wireContext, err := tracer.Extract(opentracing.TextMap, metadataReaderWriter{md})
if err != nil && err != opentracing.ErrSpanContextNotFound {
logger.Log("err", err)
}
span = tracer.StartSpan(operationName, ext.RPCServerOption(wireContext))
return opentracing.ContextWithSpan(ctx, span)
}
}
// FromHTTPRequest returns an http RequestFunc that tries to join with an
// OpenTracing trace found in `req` and starts a new Span called
// `operationName` accordingly. If no trace could be found in `req`, the Span
// will be a trace root. The Span is incorporated in the returned Context and
// can be retrieved with opentracing.SpanFromContext(ctx).
func FromHTTPRequest(tracer opentracing.Tracer, operationName string, logger log.Logger) kithttp.RequestFunc {
return func(ctx context.Context, req *http.Request) context.Context {
// Try to join to a trace propagated in `req`.
var span opentracing.Span
wireContext, err := tracer.Extract(
opentracing.TextMap,
opentracing.HTTPHeadersCarrier(req.Header),
)
if err != nil && err != opentracing.ErrSpanContextNotFound {
logger.Log("err", err)
}
span = tracer.StartSpan(operationName, ext.RPCServerOption(wireContext))
return opentracing.ContextWithSpan(ctx, span)
}
}
// extractInboundSpan attempts to create a new OpenTracing Span for inbound request
// using only trace IDs stored in the frame's tracing field. It only works if the
// tracer understand Zipkin-style trace IDs. If such attempt fails, another attempt
// will be made from the higher level function ExtractInboundSpan() once the
// application headers are read from the wire.
func (c *Connection) extractInboundSpan(callReq *callReq) opentracing.Span {
spanCtx, err := c.Tracer().Extract(zipkinSpanFormat, &callReq.Tracing)
if err != nil {
if err != opentracing.ErrUnsupportedFormat && err != opentracing.ErrSpanContextNotFound {
c.log.WithFields(ErrField(err)).Error("Failed to extract Zipkin-style span.")
}
return nil
}
if spanCtx == nil {
return nil
}
operationName := "" // not known at this point, will be set later
span := c.Tracer().StartSpan(operationName, ext.RPCServerOption(spanCtx))
span.SetTag("as", callReq.Headers[ArgScheme])
ext.PeerService.Set(span, callReq.Headers[CallerName])
c.setPeerHostPort(span)
return span
}
func (h handler) createSpan(ctx context.Context, req *http.Request, treq *transport.Request, start time.Time) (context.Context, opentracing.Span) {
// Extract opentracing etc baggage from headers
// Annotate the inbound context with a trace span
tracer := h.Deps.Tracer()
carrier := opentracing.HTTPHeadersCarrier(req.Header)
parentSpanCtx, _ := tracer.Extract(opentracing.HTTPHeaders, carrier)
// parentSpanCtx may be nil, ext.RPCServerOption handles a nil parent
// gracefully.
span := tracer.StartSpan(
treq.Procedure,
opentracing.StartTime(start),
opentracing.Tags{
"rpc.caller": treq.Caller,
"rpc.service": treq.Service,
"rpc.encoding": treq.Encoding,
"rpc.transport": "http",
},
ext.RPCServerOption(parentSpanCtx), // implies ChildOf
)
ext.PeerService.Set(span, treq.Caller)
ctx = opentracing.ContextWithSpan(ctx, span)
return ctx, span
}
func main() {
storage, err := tracer.NewGRPC("localhost:9999", &tracer.GRPCOptions{
QueueSize: 1024,
FlushInterval: 1 * time.Second,
}, grpc.WithInsecure())
if err != nil {
log.Fatal(err)
}
t1 := tracer.NewTracer("frontend", storage, tracer.RandomID{})
t2 := tracer.NewTracer("backend", storage, tracer.RandomID{})
s1 := t1.StartSpan("frontend", ext.RPCServerOption(nil))
ext.HTTPUrl.Set(s1, "/hello")
ext.HTTPMethod.Set(s1, "GET")
s2 := t1.StartSpan("backend.hello", opentracing.ChildOf(s1.Context()))
ext.SpanKindRPCClient.Set(s2)
ext.Component.Set(s2, "grpc")
carrier := opentracing.TextMapCarrier{}
if err := t1.Inject(s2.Context(), opentracing.TextMap, carrier); err != nil {
log.Println(err)
}
c3, err := t2.Extract(opentracing.TextMap, carrier)
if err != nil {
log.Println(err)
}
s3 := t2.StartSpan("backend.hello", ext.RPCServerOption(c3))
ext.Component.Set(s3, "grpc")
s4 := t2.StartSpan("mysql", opentracing.ChildOf(s3.Context()))
ext.SpanKindRPCClient.Set(s4)
ext.Component.Set(s4, "mysql")
s4.SetTag("sql.query", "SELECT * FROM table1")
// The MySQL server is not instrumented, so we only get the client
// span.
s4.Finish()
s5 := t2.StartSpan("redis", opentracing.ChildOf(s3.Context()))
ext.SpanKindRPCClient.Set(s5)
ext.Component.Set(s5, "redis")
// The Redis server is not instrumented, so we only get the client
// span.
s5.Finish()
s3.Finish()
s2.Finish()
s6 := t1.StartSpan("backend.ads", opentracing.ChildOf(s1.Context()))
ext.SpanKindRPCClient.Set(s6)
ext.Component.Set(s6, "grpc")
carrier = opentracing.TextMapCarrier{}
if err := t1.Inject(s6.Context(), opentracing.TextMap, carrier); err != nil {
log.Println(err)
}
c7, err := t2.Extract(opentracing.TextMap, carrier)
if err != nil {
log.Println(err)
}
s7 := t2.StartSpan("backend.ads", ext.RPCServerOption(c7))
ext.Component.Set(s7, "grpc")
s7.Finish()
s6.Finish()
ext.HTTPStatusCode.Set(s1, 200)
s1.Finish()
// Wait for spans to be flushed. Production code wouldn't need
// this.
time.Sleep(2 * time.Second)
}