super-graph/internal/serv/telemetry.go

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package serv
import (
"fmt"
"net/http"
"strconv"
"sync"
"contrib.go.opencensus.io/exporter/aws"
"contrib.go.opencensus.io/exporter/prometheus"
"contrib.go.opencensus.io/exporter/stackdriver"
"contrib.go.opencensus.io/exporter/zipkin"
"contrib.go.opencensus.io/integrations/ocsql"
stdzipkin "github.com/openzipkin/zipkin-go"
httpreporter "github.com/openzipkin/zipkin-go/reporter/http"
"go.opencensus.io/stats/view"
"go.opencensus.io/trace"
"go.opencensus.io/zpages"
)
func enableObservability(mux *http.ServeMux) (func(), error) {
// Enable OpenCensus zPages
if conf.Telemetry.Debug {
zpages.Handle(mux, "/telemetry")
}
// Enable ocsql metrics with OpenCensus
ocsql.RegisterAllViews()
var mex view.Exporter
var tex trace.Exporter
var mCloseFn, tCloseFn func()
var err error
// Set up the metrics exporter
switch conf.Telemetry.Metrics.Exporter {
case "prometheus":
ep := "/metrics"
if conf.Telemetry.Metrics.Endpoint != "" {
ep = conf.Telemetry.Metrics.Endpoint
}
ex, err1 := prometheus.NewExporter(prometheus.Options{Namespace: conf.Telemetry.Metrics.Namespace})
if err == nil {
mux.Handle(ep, ex)
log.Printf("INF Prometheus exporter listening on: %s", ep)
}
mex, err = view.Exporter(ex), err1
case "stackdriver":
mex, err = stackdriver.NewExporter(stackdriver.Options{ProjectID: conf.Telemetry.Metrics.Key})
if err == nil {
log.Println("INF Google Stackdriver exporter initialized")
}
case "":
log.Println("WRN OpenCensus: no metrics exporter defined")
default:
err = fmt.Errorf("invalid metrics exporter")
}
if err != nil {
return nil, fmt.Errorf("ERR OpenCensus: %s: %v", conf.Telemetry.Metrics, err)
}
if mex != nil {
// Register the exporter
view.RegisterExporter(mex)
}
// Set up the tracing exporter
switch conf.Telemetry.Tracing.Exporter {
case "xray", "aws":
ex, err1 := aws.NewExporter(aws.WithVersion("latest"))
if err == nil {
tCloseFn = func() { ex.Flush() }
log.Println("INF Amazon X-Ray exporter initialized")
}
tex, err = trace.Exporter(ex), err1
case "zipkin":
// The local endpoint stores the name and address of the local service
lep, err := stdzipkin.NewEndpoint(conf.AppName, conf.hostPort)
if err != nil {
return nil, err
}
// The Zipkin reporter takes collected spans from the app and reports them to the backend
// http://localhost:9411/api/v2/spans is the default for the Zipkin Span v2
re := httpreporter.NewReporter(conf.Telemetry.Tracing.Endpoint)
tCloseFn = func() { re.Close() }
tex = zipkin.NewExporter(re, lep)
case "":
log.Println("WRN OpenCensus: no traceing exporter defined")
default:
err = fmt.Errorf("invalid tracing exporter")
}
if err != nil {
return nil, fmt.Errorf("ERR OpenCensus: %s: %v",
conf.Telemetry.Tracing.Exporter,
err)
}
if tex != nil {
trace.RegisterExporter(tex)
sample := conf.Telemetry.Tracing.Sample
if sample == "always" {
trace.ApplyConfig(trace.Config{DefaultSampler: trace.AlwaysSample()})
} else {
prob := 0.5
if v, err := strconv.ParseFloat(sample, 10); err == nil {
prob = v
}
trace.ApplyConfig(trace.Config{DefaultSampler: trace.ProbabilitySampler(prob)})
}
}
var closeOnce sync.Once
return func() {
// Flush and shutdown the Zipkin HTTP reporter
closeOnce.Do(func() {
if mCloseFn != nil {
mCloseFn()
}
if tCloseFn != nil {
tCloseFn()
}
})
}, err
}