TUN-6250: Add upstream response status code to tracing span attributes

Author: joliveirinha

ingress/origin_proxy.go

@@ -1,6 +1,7 @@
 package ingress
 
 import (
+	"fmt"
 	"net"
 	"net/http"
 
@@ -49,7 +50,13 @@ func (o *httpService) RoundTrip(req *http.Request) (*http.Response, error) {
 }
 
 func (o *statusCode) RoundTrip(_ *http.Request) (*http.Response, error) {
-	return o.resp, nil
+	resp := &http.Response{
+		StatusCode: o.code,
+		Status:     fmt.Sprintf("%d %s", o.code, http.StatusText(o.code)),
+		Body:       new(NopReadCloser),
+	}
+
+	return resp, nil
 }
 
 func (o *rawTCPService) EstablishConnection(dest string) (OriginConnection, error) {

ingress/origin_service.go

@@ -238,20 +238,15 @@ func (o helloWorld) MarshalJSON() ([]byte, error) {
 // statusCode is an OriginService that just responds with a given HTTP status.
 // Typical use-case is "user wants the catch-all rule to just respond 404".
 type statusCode struct {
-	resp *http.Response
+	code int
 }
 
 func newStatusCode(status int) statusCode {
-	resp := &http.Response{
-		StatusCode: status,
-		Status:     fmt.Sprintf("%d %s", status, http.StatusText(status)),
-		Body:       new(NopReadCloser),
-	}
-	return statusCode{resp: resp}
+	return statusCode{code: status}
 }
 
 func (o *statusCode) String() string {
-	return fmt.Sprintf("http_status:%d", o.resp.StatusCode)
+	return fmt.Sprintf("http_status:%d", o.code)
 }
 
 func (o *statusCode) start(

proxy/proxy.go

@@ -11,7 +11,6 @@ import (
 	"github.com/pkg/errors"
 	"github.com/rs/zerolog"
 	"go.opentelemetry.io/otel/attribute"
-	"go.opentelemetry.io/otel/codes"
 	"go.opentelemetry.io/otel/trace"
 
 	"github.com/cloudflare/cloudflared/carrier"
@@ -197,10 +196,11 @@ func (p *Proxy) proxyHTTPRequest(
 	_, ttfbSpan := tr.Tracer().Start(tr.Context(), "ttfb_origin")
 	resp, err := httpService.RoundTrip(roundTripReq)
 	if err != nil {
-		tracing.EndWithStatus(ttfbSpan, codes.Error, "")
+		tracing.EndWithErrorStatus(ttfbSpan, err)
 		return errors.Wrap(err, "Unable to reach the origin service. The service may be down or it may not be responding to traffic from cloudflared")
 	}
-	tracing.EndWithStatus(ttfbSpan, codes.Ok, resp.Status)
+
+	tracing.EndWithStatusCode(ttfbSpan, resp.StatusCode)
 	defer resp.Body.Close()
 
 	// resp headers can be nil

tracing/tracing.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"math"
 	"net/http"
 	"os"
 	"runtime"
@@ -29,6 +30,9 @@ const (
 	TracerContextNameOverride = "uber-trace-id"
 
 	IntCloudflaredTracingHeader = "cf-int-cloudflared-tracing"
+
+	MaxErrorDescriptionLen = 100
+	traceHttpStatusCodeKey = "upstreamStatusCode"
 )
 
 var (
@@ -130,12 +134,35 @@ func (cft *TracedRequest) AddSpans(headers http.Header, log *zerolog.Logger) {
 	headers[CanonicalCloudflaredTracingHeader] = []string{enc}
 }
 
-// EndWithStatus will set a status for the span and then end it.
-func EndWithStatus(span trace.Span, code codes.Code, status string) {
+// EndWithErrorStatus will set a status for the span and then end it.
+func EndWithErrorStatus(span trace.Span, err error) {
+	endSpan(span, -1, codes.Error, err)
+}
+
+// EndWithStatusCode will set a status for the span and then end it.
+func EndWithStatusCode(span trace.Span, statusCode int) {
+	endSpan(span, statusCode, codes.Ok, nil)
+}
+
+// EndWithErrorStatus will set a status for the span and then end it.
+func endSpan(span trace.Span, upstreamStatusCode int, spanStatusCode codes.Code, err error) {
 	if span == nil {
 		return
 	}
-	span.SetStatus(code, status)
+
+	if upstreamStatusCode > 0 {
+		span.SetAttributes(attribute.Int(traceHttpStatusCodeKey, upstreamStatusCode))
+	}
+
+	// add error to status buf cap description
+	errDescription := ""
+	if err != nil {
+		errDescription = err.Error()
+		l := int(math.Min(float64(len(errDescription)), MaxErrorDescriptionLen))
+		errDescription = errDescription[:l]
+	}
+
+	span.SetStatus(spanStatusCode, errDescription)
 	span.End()
 }