/
tracer.go
84 lines (68 loc) · 2.16 KB
/
tracer.go
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// Package tracer provides functionality for using Jaeger and OpenTracing for
// instrumenting HTTP requests to collect metrics.
package tracer
import (
"fmt"
"io"
"net/http"
"time"
"github.com/opentracing/opentracing-go"
"github.com/uber/jaeger-client-go"
"github.com/uber/jaeger-client-go/config"
"github.com/uber/jaeger-lib/metrics"
)
const (
samplerProbability = 1
samplerType = jaeger.SamplerTypeConst
operationName = "HTTP request"
)
// RoundTripperFunc allows functions to satisfy the http.RoundTripper
// interface.
type RoundTripperFunc func(req *http.Request) (*http.Response, error)
// RoundTrip implements the http.RoundTripper interface.
func (rt RoundTripperFunc) RoundTrip(req *http.Request) (*http.Response, error) {
return rt(req)
}
// New returns a new opentracing.Tracer and io.Closer to be used for
// instrumenting HTTP requests to collect metrics.
func New(serviceName string) (opentracing.Tracer, io.Closer, error) {
cfg := config.Configuration{
ServiceName: serviceName,
Sampler: &config.SamplerConfig{
Type: samplerType,
Param: samplerProbability,
},
Reporter: &config.ReporterConfig{
BufferFlushInterval: time.Second,
},
}
tracer, closer, err := cfg.NewTracer(
config.Logger(jaeger.NullLogger),
config.Metrics(metrics.NullFactory),
)
if err != nil {
return nil, nil, fmt.Errorf("could not initialize Jaeger tracer: %w", err)
}
return tracer, closer, nil
}
// RoundTripper is http.RoundTripper middleware to add Jaeger tracing to all
// HTTP requests.
func RoundTripper(jaegerTracer opentracing.Tracer, instanceName string, next http.RoundTripper) RoundTripperFunc {
return func(req *http.Request) (*http.Response, error) {
if jaegerTracer == nil {
return next.RoundTrip(req)
}
span, traceCtx := opentracing.StartSpanFromContextWithTracer(req.Context(), jaegerTracer, operationName)
defer span.Finish()
span.SetTag("url", req.URL.Path)
span.SetTag("instance", instanceName)
span.SetTag("method", req.Method)
resp, err := next.RoundTrip(req.Clone(traceCtx))
if err != nil {
span.SetTag("error", err.Error())
return resp, err
}
span.SetTag("response", resp.StatusCode)
return resp, err
}
}