rushlink/metrics.go

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package rushlink
import (
"log"
"net/http"
"time"
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"gitea.hashru.nl/dsprenkels/rushlink/internal/db"
"github.com/gorilla/mux"
"github.com/pkg/errors"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
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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"})
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func metricURLsTotal(database *db.Database) float64 {
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var metric float64
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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
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}
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metric = float64(count)
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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
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func StartMetricsServer(addr string, database *db.Database, fs *db.FileStore) {
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prometheus.MustRegister(metricRequestsTotalCounter)
prometheus.MustRegister(prometheus.NewGaugeFunc(prometheus.GaugeOpts{
Namespace: metricNamespace,
Subsystem: "pastes",
Name: "urls_total",
Help: "The current amount of pastes in the database.",
}, func() float64 { return metricURLsTotal(database) }))
router := mux.NewRouter()
router.Handle("/metrics", promhttp.Handler()).Methods("GET")
srv := &http.Server{
Handler: router,
Addr: addr,
WriteTimeout: 15 * time.Second,
ReadTimeout: 15 * time.Second,
}
log.Fatal(srv.ListenAndServe())
}