Browse Source

Refactor metric collection

pull/72/head
Daan Sprenkels 5 months ago
parent
commit
a26894dac8
  1. 83
      metrics.go
  2. 5
      router.go

83
metrics.go

@ -14,42 +14,37 @@ import (
const metricNamespace = "rushlink"
var metricRequestsTotalCounter = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: metricNamespace,
Subsystem: "http",
Name: "requests_total",
Help: "How many HTTP requests processed, partitioned by status code and HTTP method.",
}, []string{"code", "method"})
func metricURLsTotal(database *db.Database) float64 {
var metric float64
if err := database.Transaction(func(tx *db.Database) error {
var count int64
if err := database.Model(&db.Paste{}).Count(&count).Error; err != nil {
return err
}
metric = float64(count)
return nil
}); err != nil {
log.Printf("error: %v", errors.Wrap(err, "fetching pastes_total metric"))
return 0
}
return metric
}
// StartMetricsServer starts sering Prometheus metrics exports on addr
func StartMetricsServer(addr string, database *db.Database, fs *db.FileStore) {
prometheus.MustRegister(metricRequestsTotalCounter)
// metricURLsTotalGauge counts the number of requests that are handled by
// the application, partitioned by status code and HTTP method.
//
// This counter is updated by throughout the application.
var metricRequestsTotalCounter = prometheus.NewCounterVec(
prometheus.CounterOpts{
Namespace: metricNamespace,
Subsystem: "http",
Name: "requests_total",
Help: "How many HTTP requests processed, partitioned by status code and HTTP method.",
}, []string{"code", "method"})
prometheus.MustRegister(prometheus.NewGaugeFunc(prometheus.GaugeOpts{
// metricURLsTotalGauge measures the amount of pastes stored in the database,
// partitioned by type and state.
//
// Its values are computed on the fly by updateMetrics().
var metricURLsTotalGauge = prometheus.NewGaugeVec(
prometheus.GaugeOpts{
Namespace: metricNamespace,
Subsystem: "pastes",
Name: "urls_total",
Help: "The current amount of pastes in the database.",
}, func() float64 { return metricURLsTotal(database) }))
Help: "The current amount of pastes in the database, partitioned by state and type.",
}, []string{"state", "type"})
// StartMetricsServer starts sering Prometheus metrics exports on addr
func StartMetricsServer(addr string, database *db.Database, fs *db.FileStore) {
prometheus.MustRegister(metricRequestsTotalCounter)
prometheus.MustRegister(metricURLsTotalGauge)
router := mux.NewRouter()
router.Handle("/metrics", promhttp.Handler()).Methods("GET")
router.Handle("/metrics", &MetricsHandler{database}).Methods("GET")
srv := &http.Server{
Handler: router,
Addr: addr,
@ -58,3 +53,31 @@ func StartMetricsServer(addr string, database *db.Database, fs *db.FileStore) {
}
log.Fatal(srv.ListenAndServe())
}
type MetricsHandler struct {
db *db.Database
}
func (mh *MetricsHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
mh.updateMetrics()
promhttp.Handler().ServeHTTP(w, r)
}
func (mh *MetricsHandler) updateMetrics() {
// Update metricURLsTotalGauge
for state := db.PasteStateUndef; state <= db.PasteStateDeleted; state++ {
for ty := db.PasteTypeUndef; ty <= db.PasteTypeFileUpload; ty++ {
var count int64
query := mh.db.Unscoped().Model(&db.Paste{}).Where("type = ? AND state = ?", ty, state).Count(&count)
if err := query.Error; err != nil {
log.Printf("error: %v", errors.Wrap(err, "fetching pastes_total metric"))
return
}
labels := map[string]string{
"state": state.String(),
"type": ty.String(),
}
metricURLsTotalGauge.With(labels).Set(float64(count))
}
}
}

5
router.go

@ -60,8 +60,11 @@ func (rl *rushlink) metricsMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
srw := statusResponseWriter{Inner: w}
next.ServeHTTP(&srw, r)
status := strconv.Itoa(srw.StatusCode)
metricRequestsTotalCounter.WithLabelValues(status, r.Method).Inc()
labels := map[string]string{"code": status, "method": r.Method}
// Update requests counter metric
metricRequestsTotalCounter.With(labels).Inc()
})
}

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