/
tracing.go
190 lines (165 loc) · 5.18 KB
/
tracing.go
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package tracing
// Copyright 2018 Microsoft Corporation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
import (
"context"
"fmt"
"net/http"
"os"
"contrib.go.opencensus.io/exporter/ocagent"
"go.opencensus.io/plugin/ochttp"
"go.opencensus.io/plugin/ochttp/propagation/tracecontext"
"go.opencensus.io/stats/view"
"go.opencensus.io/trace"
)
var (
// Transport is the default tracing RoundTripper. The custom options setter will control
// if traces are being emitted or not.
Transport = &ochttp.Transport{
Propagation: &tracecontext.HTTPFormat{},
GetStartOptions: getStartOptions,
}
// enabled is the flag for marking if tracing is enabled.
enabled = false
// Sampler is the tracing sampler. If tracing is disabled it will never sample. Otherwise
// it will be using the parent sampler or the default.
sampler = trace.NeverSample()
// Views for metric instrumentation.
views = map[string]*view.View{}
// the trace exporter
traceExporter trace.Exporter
)
func init() {
enableFromEnv()
}
func enableFromEnv() {
_, ok := os.LookupEnv("AZURE_SDK_TRACING_ENABLED")
_, legacyOk := os.LookupEnv("AZURE_SDK_TRACING_ENABELD")
if ok || legacyOk {
agentEndpoint, ok := os.LookupEnv("OCAGENT_TRACE_EXPORTER_ENDPOINT")
if ok {
EnableWithAIForwarding(agentEndpoint)
} else {
Enable()
}
}
}
// IsEnabled returns true if monitoring is enabled for the sdk.
func IsEnabled() bool {
return enabled
}
// Enable will start instrumentation for metrics and traces.
func Enable() error {
enabled = true
sampler = nil
err := initStats()
return err
}
// Disable will disable instrumentation for metrics and traces.
func Disable() {
disableStats()
sampler = trace.NeverSample()
if traceExporter != nil {
trace.UnregisterExporter(traceExporter)
}
enabled = false
}
// EnableWithAIForwarding will start instrumentation and will connect to app insights forwarder
// exporter making the metrics and traces available in app insights.
func EnableWithAIForwarding(agentEndpoint string) (err error) {
err = Enable()
if err != nil {
return err
}
traceExporter, err := ocagent.NewExporter(ocagent.WithInsecure(), ocagent.WithAddress(agentEndpoint))
if err != nil {
return err
}
trace.RegisterExporter(traceExporter)
return
}
// getStartOptions is the custom options setter for the ochttp package.
func getStartOptions(*http.Request) trace.StartOptions {
return trace.StartOptions{
Sampler: sampler,
}
}
// initStats registers the views for the http metrics
func initStats() (err error) {
clientViews := []*view.View{
ochttp.ClientCompletedCount,
ochttp.ClientRoundtripLatencyDistribution,
ochttp.ClientReceivedBytesDistribution,
ochttp.ClientSentBytesDistribution,
}
for _, cv := range clientViews {
vn := fmt.Sprintf("Azure/go-autorest/tracing-%s", cv.Name)
views[vn] = cv.WithName(vn)
err = view.Register(views[vn])
if err != nil {
return err
}
}
return
}
// disableStats will unregister the previously registered metrics
func disableStats() {
for _, v := range views {
view.Unregister(v)
}
}
// StartSpan starts a trace span
func StartSpan(ctx context.Context, name string) context.Context {
ctx, _ = trace.StartSpan(ctx, name, trace.WithSampler(sampler))
return ctx
}
// EndSpan ends a previously started span stored in the context
func EndSpan(ctx context.Context, httpStatusCode int, err error) {
span := trace.FromContext(ctx)
if span == nil {
return
}
if err != nil {
span.SetStatus(trace.Status{Message: err.Error(), Code: toTraceStatusCode(httpStatusCode)})
}
span.End()
}
// toTraceStatusCode converts HTTP Codes to OpenCensus codes as defined
// at https://github.com/census-instrumentation/opencensus-specs/blob/master/trace/HTTP.md#status
func toTraceStatusCode(httpStatusCode int) int32 {
switch {
case http.StatusOK <= httpStatusCode && httpStatusCode < http.StatusBadRequest:
return trace.StatusCodeOK
case httpStatusCode == http.StatusBadRequest:
return trace.StatusCodeInvalidArgument
case httpStatusCode == http.StatusUnauthorized: // 401 is actually unauthenticated.
return trace.StatusCodeUnauthenticated
case httpStatusCode == http.StatusForbidden:
return trace.StatusCodePermissionDenied
case httpStatusCode == http.StatusNotFound:
return trace.StatusCodeNotFound
case httpStatusCode == http.StatusTooManyRequests:
return trace.StatusCodeResourceExhausted
case httpStatusCode == 499:
return trace.StatusCodeCancelled
case httpStatusCode == http.StatusNotImplemented:
return trace.StatusCodeUnimplemented
case httpStatusCode == http.StatusServiceUnavailable:
return trace.StatusCodeUnavailable
case httpStatusCode == http.StatusGatewayTimeout:
return trace.StatusCodeDeadlineExceeded
default:
return trace.StatusCodeUnknown
}
}