internal/dcensus/dcensus.go - pkgsite - Git at Google

 // Copyright 2019 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 // Package dcensus provides functionality for debug instrumentation.
 package dcensus

 import (
 	"context"
 	"fmt"
 	"net/http"
 	"strings"
 	"time"

 	"contrib.go.opencensus.io/exporter/prometheus"
 	"contrib.go.opencensus.io/exporter/stackdriver"
 	"go.opencensus.io/plugin/ochttp"
 	"go.opencensus.io/stats"
 	"go.opencensus.io/stats/view"
 	"go.opencensus.io/tag"
 	"go.opencensus.io/trace"
 	"go.opencensus.io/zpages"
 	"golang.org/x/pkgsite/internal/config"
 	"golang.org/x/pkgsite/internal/derrors"
 	"golang.org/x/pkgsite/internal/log"
 	mrpb "google.golang.org/genproto/googleapis/api/monitoredres"
 )

 // KeyStatus is a tag key named "status".
 var KeyStatus = tag.MustNewKey("status")

 // RouteTagger is a func that can be used to derive a dynamic route tag for an
 // incoming request.
 type RouteTagger func(route string, r *http.Request) string

 // Router is an http multiplexer that instruments per-handler debugging
 // information and census instrumentation.
 type Router struct {
 	http.Handler
 	mux    *http.ServeMux
 	tagger RouteTagger
 }

 // NewRouter creates a new Router, using tagger to tag incoming requests in
 // monitoring. If tagger is nil, a default route tagger is used.
 func NewRouter(tagger RouteTagger) *Router {
 	if tagger == nil {
 		tagger = func(route string, r *http.Request) string {
 			return strings.Trim(route, "/")
 		}
 	}
 	mux := http.NewServeMux()
 	return &Router{
 		mux:     mux,
 		Handler: &ochttp.Handler{Handler: mux},
 		tagger:  tagger,
 	}
 }

 // Handle registers handler with the given route. It has the same routing
 // semantics as http.ServeMux.
 func (r *Router) Handle(route string, handler http.Handler) {
 	r.mux.HandleFunc(route, func(w http.ResponseWriter, req *http.Request) {
 		tag := r.tagger(route, req)
 		ochttp.WithRouteTag(handler, tag).ServeHTTP(w, req)
 	})
 }

 // HandleFunc is a wrapper around Handle for http.HandlerFuncs.
 func (r *Router) HandleFunc(route string, handler http.HandlerFunc) {
 	r.Handle(route, handler)
 }

 const debugPage = `
 <html>
 <p><a href="/tracez">/tracez</a> - trace spans</p>
 <p><a href="/statsz">/statz</a> - prometheus metrics page</p>
 `

 // Init configures tracing and aggregation according to the given Views. If
 // running on GCP, Init also configures exporting to StackDriver.
 func Init(cfg *config.Config, views ...*view.View) error {
 	// The default trace sampler samples with probability 1e-4. That's too
 	// infrequent for our traffic levels. In the future we may want to decrease
 	// this sampling rate.
 	trace.ApplyConfig(trace.Config{DefaultSampler: trace.ProbabilitySampler(0.01)})
 	if err := view.Register(views...); err != nil {
 		return fmt.Errorf("dcensus.Init(views): view.Register: %v", err)
 	}
 	exportToStackdriver(context.Background(), cfg)
 	return nil
 }

 // NewServer creates a new http.Handler for serving debug information.
 func NewServer() (http.Handler, error) {
 	pe, err := prometheus.NewExporter(prometheus.Options{})
 	if err != nil {
 		return nil, fmt.Errorf("dcensus.NewServer: prometheus.NewExporter: %v", err)
 	}
 	mux := http.NewServeMux()
 	zpages.Handle(mux, "/")
 	mux.Handle("/statsz", pe)
 	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		fmt.Fprint(w, debugPage)
 	})

 	return mux, nil
 }

 // monitoredResource wraps a *mrpb.MonitoredResource to implement the
 // monitoredresource.MonitoredResource interface.
 type monitoredResource mrpb.MonitoredResource

 func (r *monitoredResource) MonitoredResource() (resType string, labels map[string]string) {
 	return r.Type, r.Labels
 }

 // ExportToStackdriver checks to see if the process is running in a GCP
 // environment, and if so configures exporting to stackdriver.
 func exportToStackdriver(ctx context.Context, cfg *config.Config) {
 	if cfg.ProjectID == "" {
 		log.Infof(ctx, "Not exporting to StackDriver: GOOGLE_CLOUD_PROJECT is unset.")
 		return
 	}

 	// Report statistics every minutes, due to stackdriver limitations described at
 	// https://cloud.google.com/monitoring/custom-metrics/creating-metrics#writing-ts
 	view.SetReportingPeriod(time.Minute)

 	viewExporter, err := NewViewExporter(cfg)
 	if err != nil {
 		log.Fatalf(ctx, "error creating view exporter: %v", err)
 	}
 	view.RegisterExporter(viewExporter)

 	dte := &debugTraceExporter{}
 	// We want traces to be associated with the *app*, not the instance.
 	// TraceSpansBufferMaxBytes is increased from the default of 8MiB, though we
 	// can't increase *too* much because this is still running in GAE, which is
 	// relatively memory-constrained.
 	traceExporter, err := stackdriver.NewExporter(stackdriver.Options{
 		ProjectID:                cfg.ProjectID,
 		MonitoredResource:        (*monitoredResource)(cfg.MonitoredResource),
 		TraceSpansBufferMaxBytes: 32 * 1024 * 1024, // 32 MiB
 		DefaultMonitoringLabels:  stackdriverLabels(cfg),
 		OnError:                  dte.onError,
 	})
 	if err != nil {
 		log.Fatalf(ctx, "error creating trace exporter: %v", err)
 	}
 	dte.exp = traceExporter
 	trace.RegisterExporter(dte)
 }

 // NewViewExporter creates a StackDriver exporter for stats.
 func NewViewExporter(cfg *config.Config) (_ *stackdriver.Exporter, err error) {
 	defer derrors.Wrap(&err, "NewViewExporter()")

 	// Views must be associated with the instance, else we run into overlapping
 	// timeseries problems. Note that generic_task is used because the
 	// gae_instance resource type is not supported for metrics:
 	// https://cloud.google.com/monitoring/custom-metrics/creating-metrics#which-resource
 	mr := &monitoredResource{
 		Type: "generic_task",
 		Labels: map[string]string{
 			"project_id": cfg.ProjectID,
 			"location":   cfg.LocationID,
 			"job":        cfg.ServiceID,
 			"namespace":  "go-discovery",
 			"task_id":    cfg.InstanceID,
 		},
 	}
 	if cfg.OnGKE() {
 		mr = (*monitoredResource)(cfg.MonitoredResource)
 	}
 	return stackdriver.NewExporter(stackdriver.Options{
 		ProjectID:               cfg.ProjectID,
 		MonitoredResource:       mr,
 		DefaultMonitoringLabels: stackdriverLabels(cfg),
 		OnError: func(err error) {
 			log.Warningf(context.Background(), "Stackdriver view exporter: %v", err)
 		},
 	})
 }

 func stackdriverLabels(cfg *config.Config) *stackdriver.Labels {
 	labels := &stackdriver.Labels{}
 	labels.Set("version", cfg.AppVersionLabel(), "Version label of the running binary")
 	labels.Set("env", cfg.DeploymentEnvironment(), "deployment environment")
 	labels.Set("app", cfg.Application(), "application name")
 	return labels
 }

 // Customizations of ochttp views. Views are updated as follows:
 //  + ClientHost and ServerRoute are added to resp. client and server metrics.
 //    Since these are bounded cardinality in our metrics, they are useful to
 //    add additional context.
 //  + Method tags are removed. We don't have any routes that accept more than
 //    one HTTP method.
 var (
 	ServerRequestCount = &view.View{
 		Name:        "go-discovery/http/server/request_count",
 		Description: "Count of HTTP requests started by Method",
 		TagKeys:     []tag.Key{ochttp.Method},
 		Measure:     ochttp.ServerRequestCount,
 		Aggregation: view.Count(),
 	}
 	ServerResponseCount = &view.View{
 		Name:        "go-discovery/http/server/response_count",
 		Description: "Server response count by status code and route",
 		TagKeys:     []tag.Key{ochttp.StatusCode, ochttp.KeyServerRoute},
 		Measure:     ochttp.ServerLatency,
 		Aggregation: view.Count(),
 	}
 	ServerLatency = &view.View{
 		Name:        "go-discovery/http/server/response_latency",
 		Description: "Server response distribution by status code and route",
 		TagKeys:     []tag.Key{ochttp.KeyServerRoute},
 		Measure:     ochttp.ServerLatency,
 		Aggregation: ochttp.DefaultLatencyDistribution,
 	}
 	ServerResponseBytes = &view.View{
 		Name:        "go-discovery/http/server/response_bytes",
 		Description: "Size distribution of HTTP response body",
 		TagKeys:     []tag.Key{ochttp.KeyServerRoute},
 		Measure:     ochttp.ServerResponseBytes,
 		Aggregation: ochttp.DefaultSizeDistribution,
 	}
 	ServerViews = []*view.View{
 		ServerRequestCount,
 		ServerResponseCount,
 		ServerLatency,
 		ServerResponseBytes,
 	}
 )

 // RecordWithTag is a convenience function for recording a single measurement with a single tag.
 func RecordWithTag(ctx context.Context, key tag.Key, val string, m stats.Measurement) {
 	stats.RecordWithTags(ctx, []tag.Mutator{tag.Upsert(key, val)}, m)
 }
	// Copyright 2019 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	// Package dcensus provides functionality for debug instrumentation.
	package dcensus

	import (
	"context"
	"fmt"
	"net/http"
	"strings"
	"time"

	"contrib.go.opencensus.io/exporter/prometheus"
	"contrib.go.opencensus.io/exporter/stackdriver"
	"go.opencensus.io/plugin/ochttp"
	"go.opencensus.io/stats"
	"go.opencensus.io/stats/view"
	"go.opencensus.io/tag"
	"go.opencensus.io/trace"
	"go.opencensus.io/zpages"
	"golang.org/x/pkgsite/internal/config"
	"golang.org/x/pkgsite/internal/derrors"
	"golang.org/x/pkgsite/internal/log"
	mrpb "google.golang.org/genproto/googleapis/api/monitoredres"
	)

	// KeyStatus is a tag key named "status".
	var KeyStatus = tag.MustNewKey("status")

	// RouteTagger is a func that can be used to derive a dynamic route tag for an
	// incoming request.
	type RouteTagger func(route string, r *http.Request) string

	// Router is an http multiplexer that instruments per-handler debugging
	// information and census instrumentation.
	type Router struct {
	http.Handler
	mux *http.ServeMux
	tagger RouteTagger
	}

	// NewRouter creates a new Router, using tagger to tag incoming requests in
	// monitoring. If tagger is nil, a default route tagger is used.
	func NewRouter(tagger RouteTagger) *Router {
	if tagger == nil {
	tagger = func(route string, r *http.Request) string {
	return strings.Trim(route, "/")
	}
	}
	mux := http.NewServeMux()
	return &Router{
	mux: mux,
	Handler: &ochttp.Handler{Handler: mux},
	tagger: tagger,
	}
	}

	// Handle registers handler with the given route. It has the same routing
	// semantics as http.ServeMux.
	func (r *Router) Handle(route string, handler http.Handler) {
	r.mux.HandleFunc(route, func(w http.ResponseWriter, req *http.Request) {
	tag := r.tagger(route, req)
	ochttp.WithRouteTag(handler, tag).ServeHTTP(w, req)
	})
	}

	// HandleFunc is a wrapper around Handle for http.HandlerFuncs.
	func (r *Router) HandleFunc(route string, handler http.HandlerFunc) {
	r.Handle(route, handler)
	}

	const debugPage = `
	<html>
	<p><a href="/tracez">/tracez</a> - trace spans</p>
	<p><a href="/statsz">/statz</a> - prometheus metrics page</p>
	`

	// Init configures tracing and aggregation according to the given Views. If
	// running on GCP, Init also configures exporting to StackDriver.
	func Init(cfg config.Config, views ...view.View) error {
	// The default trace sampler samples with probability 1e-4. That's too
	// infrequent for our traffic levels. In the future we may want to decrease
	// this sampling rate.
	trace.ApplyConfig(trace.Config{DefaultSampler: trace.ProbabilitySampler(0.01)})
	if err := view.Register(views...); err != nil {
	return fmt.Errorf("dcensus.Init(views): view.Register: %v", err)
	}
	exportToStackdriver(context.Background(), cfg)
	return nil
	}

	// NewServer creates a new http.Handler for serving debug information.
	func NewServer() (http.Handler, error) {
	pe, err := prometheus.NewExporter(prometheus.Options{})
	if err != nil {
	return nil, fmt.Errorf("dcensus.NewServer: prometheus.NewExporter: %v", err)
	}
	mux := http.NewServeMux()
	zpages.Handle(mux, "/")
	mux.Handle("/statsz", pe)
	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
	fmt.Fprint(w, debugPage)
	})

	return mux, nil
	}

	// monitoredResource wraps a *mrpb.MonitoredResource to implement the
	// monitoredresource.MonitoredResource interface.
	type monitoredResource mrpb.MonitoredResource

	func (r *monitoredResource) MonitoredResource() (resType string, labels map[string]string) {
	return r.Type, r.Labels
	}

	// ExportToStackdriver checks to see if the process is running in a GCP
	// environment, and if so configures exporting to stackdriver.
	func exportToStackdriver(ctx context.Context, cfg *config.Config) {
	if cfg.ProjectID == "" {
	log.Infof(ctx, "Not exporting to StackDriver: GOOGLE_CLOUD_PROJECT is unset.")
	return
	}

	// Report statistics every minutes, due to stackdriver limitations described at
	// https://cloud.google.com/monitoring/custom-metrics/creating-metrics#writing-ts
	view.SetReportingPeriod(time.Minute)

	viewExporter, err := NewViewExporter(cfg)
	if err != nil {
	log.Fatalf(ctx, "error creating view exporter: %v", err)
	}
	view.RegisterExporter(viewExporter)

	dte := &debugTraceExporter{}
	// We want traces to be associated with the app, not the instance.
	// TraceSpansBufferMaxBytes is increased from the default of 8MiB, though we
	// can't increase too much because this is still running in GAE, which is
	// relatively memory-constrained.
	traceExporter, err := stackdriver.NewExporter(stackdriver.Options{
	ProjectID: cfg.ProjectID,
	MonitoredResource: (*monitoredResource)(cfg.MonitoredResource),
	TraceSpansBufferMaxBytes: 32 * 1024 * 1024, // 32 MiB
	DefaultMonitoringLabels: stackdriverLabels(cfg),
	OnError: dte.onError,
	})
	if err != nil {
	log.Fatalf(ctx, "error creating trace exporter: %v", err)
	}
	dte.exp = traceExporter
	trace.RegisterExporter(dte)
	}

	// NewViewExporter creates a StackDriver exporter for stats.
	func NewViewExporter(cfg config.Config) (_ stackdriver.Exporter, err error) {
	defer derrors.Wrap(&err, "NewViewExporter()")

	// Views must be associated with the instance, else we run into overlapping
	// timeseries problems. Note that generic_task is used because the
	// gae_instance resource type is not supported for metrics:
	// https://cloud.google.com/monitoring/custom-metrics/creating-metrics#which-resource
	mr := &monitoredResource{
	Type: "generic_task",
	Labels: map[string]string{
	"project_id": cfg.ProjectID,
	"location": cfg.LocationID,
	"job": cfg.ServiceID,
	"namespace": "go-discovery",
	"task_id": cfg.InstanceID,
	},
	}
	if cfg.OnGKE() {
	mr = (*monitoredResource)(cfg.MonitoredResource)
	}
	return stackdriver.NewExporter(stackdriver.Options{
	ProjectID: cfg.ProjectID,
	MonitoredResource: mr,
	DefaultMonitoringLabels: stackdriverLabels(cfg),
	OnError: func(err error) {
	log.Warningf(context.Background(), "Stackdriver view exporter: %v", err)
	},
	})
	}

	func stackdriverLabels(cfg config.Config) stackdriver.Labels {
	labels := &stackdriver.Labels{}
	labels.Set("version", cfg.AppVersionLabel(), "Version label of the running binary")
	labels.Set("env", cfg.DeploymentEnvironment(), "deployment environment")
	labels.Set("app", cfg.Application(), "application name")
	return labels
	}

	// Customizations of ochttp views. Views are updated as follows:
	// + ClientHost and ServerRoute are added to resp. client and server metrics.
	// Since these are bounded cardinality in our metrics, they are useful to
	// add additional context.
	// + Method tags are removed. We don't have any routes that accept more than
	// one HTTP method.
	var (
	ServerRequestCount = &view.View{
	Name: "go-discovery/http/server/request_count",
	Description: "Count of HTTP requests started by Method",
	TagKeys: []tag.Key{ochttp.Method},
	Measure: ochttp.ServerRequestCount,
	Aggregation: view.Count(),
	}
	ServerResponseCount = &view.View{
	Name: "go-discovery/http/server/response_count",
	Description: "Server response count by status code and route",
	TagKeys: []tag.Key{ochttp.StatusCode, ochttp.KeyServerRoute},
	Measure: ochttp.ServerLatency,
	Aggregation: view.Count(),
	}
	ServerLatency = &view.View{
	Name: "go-discovery/http/server/response_latency",
	Description: "Server response distribution by status code and route",
	TagKeys: []tag.Key{ochttp.KeyServerRoute},
	Measure: ochttp.ServerLatency,
	Aggregation: ochttp.DefaultLatencyDistribution,
	}
	ServerResponseBytes = &view.View{
	Name: "go-discovery/http/server/response_bytes",
	Description: "Size distribution of HTTP response body",
	TagKeys: []tag.Key{ochttp.KeyServerRoute},
	Measure: ochttp.ServerResponseBytes,
	Aggregation: ochttp.DefaultSizeDistribution,
	}
	ServerViews = []*view.View{
	ServerRequestCount,
	ServerResponseCount,
	ServerLatency,
	ServerResponseBytes,
	}
	)

	// RecordWithTag is a convenience function for recording a single measurement with a single tag.
	func RecordWithTag(ctx context.Context, key tag.Key, val string, m stats.Measurement) {
	stats.RecordWithTags(ctx, []tag.Mutator{tag.Upsert(key, val)}, m)
	}