forked from electricdusk/rushlink
109 lines
3.2 KiB
Go
109 lines
3.2 KiB
Go
package rushlink
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import (
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"log"
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"net/http"
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"time"
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"gitea.hashru.nl/dsprenkels/rushlink/internal/db"
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"github.com/gorilla/mux"
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"github.com/pkg/errors"
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"github.com/prometheus/client_golang/prometheus"
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"github.com/prometheus/client_golang/prometheus/promhttp"
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)
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const metricNamespace = "rushlink"
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// metricURLsTotalGauge counts the number of requests that are handled by
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// the application, partitioned by status code and HTTP method.
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//
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// This counter is updated by the router.
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var metricRequestsTotalCounter = prometheus.NewCounterVec(
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prometheus.CounterOpts{
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Namespace: metricNamespace,
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Subsystem: "http",
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Name: "requests_total",
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Help: "How many HTTP requests processed, partitioned by status code and HTTP method.",
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}, []string{"code", "method"})
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// metricRequestsLatencyNanoSeconds keeps track of the request latencies for
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// each http request.
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//
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// This historogram is updated by the router.
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var metricRequestsLatencyNanoSeconds = prometheus.NewHistogramVec(
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prometheus.HistogramOpts{
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Namespace: metricNamespace,
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Subsystem: "http",
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Name: "request_duration_seconds",
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Buckets: []float64{
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float64(500e-6),
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float64(1e-3),
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float64(2e-3),
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float64(5e-3),
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float64(10e-3),
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float64(20e-3),
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float64(50e-3),
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},
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Help: "The latency of each HTTP request, partitioned by status code and HTTP method.",
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}, []string{"code", "method"})
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// metricURLsTotalGauge measures the amount of pastes stored in the database,
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// partitioned by type and state.
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//
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// Its values are computed on the fly by updateMetrics().
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var metricURLsTotalGauge = prometheus.NewGaugeVec(
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prometheus.GaugeOpts{
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Namespace: metricNamespace,
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Subsystem: "pastes",
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Name: "urls_total",
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Help: "The current amount of pastes in the database, partitioned by state and type.",
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}, []string{"state", "type"})
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// StartMetricsServer starts sering Prometheus metrics exports on addr
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func StartMetricsServer(addr string, database *db.Database, fs *db.FileStore) {
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prometheus.MustRegister(metricRequestsTotalCounter)
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prometheus.MustRegister(metricRequestsLatencyNanoSeconds)
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prometheus.MustRegister(metricURLsTotalGauge)
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router := mux.NewRouter()
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router.Handle("/metrics", &MetricsHandler{database}).Methods("GET")
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srv := &http.Server{
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Handler: router,
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Addr: addr,
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WriteTimeout: 15 * time.Second,
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ReadTimeout: 15 * time.Second,
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}
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log.Fatal(srv.ListenAndServe())
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}
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type MetricsHandler struct {
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db *db.Database
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}
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func (mh *MetricsHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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mh.updateMetrics()
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promhttp.Handler().ServeHTTP(w, r)
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}
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func (mh *MetricsHandler) updateMetrics() {
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// Update metricURLsTotalGauge
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results := make([](struct {
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Type db.PasteType
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State db.PasteState
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Count float64
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}), 0)
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query := mh.db.Unscoped().Model(&db.Paste{}).Select("type", "state", "COUNT(*) as count").Group("type, state").Find(&results)
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if err := query.Error; err != nil {
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log.Printf("error: %v", errors.Wrap(err, "fetching pastes_total metric"))
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return
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}
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metricURLsTotalGauge.Reset()
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for _, r := range results {
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labels := map[string]string{
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"type": r.Type.String(),
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"state": r.State.String(),
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}
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metricURLsTotalGauge.With(labels).Set(r.Count)
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}
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}
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