Move prometheus metrics into control job

daemon/control.go

@@ -30,8 +30,6 @@ const (
 	ControlJobEndpointSignal  string = "/signal"
 )
 
-var promControl middleware.PromControl
-
 type controlJob struct {
 	sockaddr *net.UnixAddr
 	sockmode os.FileMode
@@ -40,6 +38,9 @@ type controlJob struct {
 
 	log         logger.Logger
 	pprofServer *pprofServer
+
+	requestBegin    *prometheus.CounterVec
+	requestFinished *prometheus.HistogramVec
 }
 
 func newControlJob(sockpath string, jobs *jobs, mode uint32,
@@ -66,22 +67,22 @@ func (j *controlJob) OwnedDatasetSubtreeRoot() (p *zfs.DatasetPath, ok bool) { r
 func (j *controlJob) SenderConfig() *endpoint.SenderConfig { return nil }
 
 func (j *controlJob) RegisterMetrics(registerer prometheus.Registerer) {
-	promControl.RequestBegin = prometheus.NewCounterVec(prometheus.CounterOpts{
+	j.requestBegin = prometheus.NewCounterVec(prometheus.CounterOpts{
 		Namespace: "zrepl",
 		Subsystem: "control",
 		Name:      "request_begin",
 		Help:      "number of request we started to handle",
 	}, []string{"endpoint"})
 
-	promControl.RequestFinished = prometheus.NewHistogramVec(prometheus.HistogramOpts{
+	j.requestFinished = prometheus.NewHistogramVec(prometheus.HistogramOpts{
 		Namespace: "zrepl",
 		Subsystem: "control",
 		Name:      "request_finished",
 		Help:      "time it took a request to finish",
 		Buckets:   []float64{1e-6, 10e-6, 100e-6, 500e-6, 1e-3, 10e-3, 100e-3, 200e-3, 400e-3, 800e-3, 1, 10, 20},
 	}, []string{"endpoint"})
-	registerer.MustRegister(promControl.RequestBegin)
-	registerer.MustRegister(promControl.RequestFinished)
+	registerer.MustRegister(j.requestBegin)
+	registerer.MustRegister(j.requestFinished)
 }
 
 func (j *controlJob) Run(ctx context.Context, cron *cron.Cron) {
@@ -115,29 +116,8 @@ func (j *controlJob) Run(ctx context.Context, cron *cron.Cron) {
 		})
 	}
 
-	mux := http.NewServeMux()
-	logRequest := middleware.RequestLogger(j.log, &promControl)
-
-	mux.Handle(ControlJobEndpointPProf, middleware.New(
-		logRequest,
-		middleware.JsonRequestResponder(j.log, j.pprof)))
-
-	mux.Handle(ControlJobEndpointVersion, middleware.New(
-		logRequest,
-		middleware.JsonResponder(j.log, func() (any, error) {
-			return version.NewZreplVersionInformation(), nil
-		})))
-
-	mux.Handle(ControlJobEndpointStatus, middleware.New(
-		// don't log requests to status endpoint, too spammy
-		middleware.JsonResponder(j.log, j.status)))
-
-	mux.Handle(ControlJobEndpointSignal, middleware.New(
-		logRequest,
-		middleware.JsonRequestResponder(j.log, j.signal)))
-
 	server := http.Server{
-		Handler: mux,
+		Handler: j.mux(),
 		// control socket is local, 1s timeout should be more than sufficient, even
 		// on a loaded system
 		WriteTimeout: envconst.Duration(
@@ -169,6 +149,31 @@ func (j *controlJob) Run(ctx context.Context, cron *cron.Cron) {
 	j.pprofServer.Wait()
 }
 
+func (j *controlJob) mux() *http.ServeMux {
+	mux := http.NewServeMux()
+	logRequest := middleware.RequestLogger(j.log,
+		middleware.WithPrometheusMetrics(j.requestBegin, j.requestFinished))
+
+	mux.Handle(ControlJobEndpointPProf, middleware.New(
+		logRequest,
+		middleware.JsonRequestResponder(j.log, j.pprof)))
+
+	mux.Handle(ControlJobEndpointVersion, middleware.New(
+		logRequest,
+		middleware.JsonResponder(j.log, func() (any, error) {
+			return version.NewZreplVersionInformation(), nil
+		})))
+
+	mux.Handle(ControlJobEndpointStatus, middleware.New(
+		// don't log requests to status endpoint, too spammy
+		middleware.JsonResponder(j.log, j.status)))
+
+	mux.Handle(ControlJobEndpointSignal, middleware.New(
+		logRequest,
+		middleware.JsonRequestResponder(j.log, j.signal)))
+	return mux
+}
+
 func (j *controlJob) pprof(decoder middleware.JsonDecoder) (any, error) {
 	var msg PprofServerControlMsg
 	err := decoder(&msg)

daemon/middleware/log.go

@@ -9,17 +9,9 @@ import (
 	"github.com/dsh2dsh/zrepl/logger"
 )
 
-type PromControl struct {
-	RequestBegin    *prometheus.CounterVec
-	RequestFinished *prometheus.HistogramVec
-}
-
-func RequestLogger(log logger.Logger, prom *PromControl, opts ...loggerOption,
-) Middleware {
+func RequestLogger(log logger.Logger, opts ...loggerOption) Middleware {
 	l := &requestLogger{
-		log:  log,
-		prom: prom,
-
+		log:            log,
 		completedLevel: logger.Debug,
 	}
 
@@ -35,11 +27,22 @@ func WithCompletedInfo() loggerOption {
 	return func(self *requestLogger) { self.completedLevel = logger.Info }
 }
 
+func WithPrometheusMetrics(requestBegin *prometheus.CounterVec,
+	requestFinished *prometheus.HistogramVec,
+) loggerOption {
+	return func(self *requestLogger) {
+		self.requestBegin = requestBegin
+		self.requestFinished = requestFinished
+	}
+}
+
 type requestLogger struct {
-	log  logger.Logger
-	prom *PromControl
+	log logger.Logger
 
 	completedLevel logger.Level
+
+	requestBegin    *prometheus.CounterVec
+	requestFinished *prometheus.HistogramVec
 }
 
 func (self *requestLogger) middleware(next http.Handler) http.Handler {
@@ -53,10 +56,14 @@ func (self *requestLogger) middleware(next http.Handler) http.Handler {
 		log.Info("\"" + methodURL + "\"")
 		log = log.WithField("req", methodURL)
 
-		self.prom.RequestBegin.WithLabelValues(r.URL.Path).Inc()
-		defer prometheus.
-			NewTimer(self.prom.RequestFinished.WithLabelValues(r.URL.Path)).
-			ObserveDuration()
+		if self.requestBegin != nil {
+			self.requestBegin.WithLabelValues(r.URL.Path).Inc()
+		}
+		if self.requestFinished != nil {
+			defer prometheus.
+				NewTimer(self.requestFinished.WithLabelValues(r.URL.Path)).
+				ObserveDuration()
+		}
 
 		if next == nil {
 			log.Error("no next handler configured")
@@ -68,5 +75,6 @@ func (self *requestLogger) middleware(next http.Handler) http.Handler {
 		log.WithField("duration", time.Since(t)).
 			Log(self.completedLevel, "request completed")
 	}
+
 	return http.HandlerFunc(fn)
 }