Add Prometheus exporter

metric/metric.go

@@ -0,0 +1,120 @@
+// Copyright 2020 Frédéric Guillot. All rights reserved.
+// Use of this source code is governed by the Apache 2.0
+// license that can be found in the LICENSE file.
+
+package metric // import "miniflux.app/metric"
+
+import (
+	"time"
+
+	"miniflux.app/logger"
+	"miniflux.app/storage"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+// Prometheus Metrics.
+var (
+	BackgroundFeedRefreshDuration = prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Namespace: "miniflux",
+			Name:      "background_feed_refresh_duration",
+			Help:      "Processing time to refresh feeds from the background workers",
+			Buckets:   prometheus.LinearBuckets(1, 2, 15),
+		},
+		[]string{"status"},
+	)
+
+	ScraperRequestDuration = prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Namespace: "miniflux",
+			Name:      "scraper_request_duration",
+			Help:      "Web scraper request duration",
+			Buckets:   prometheus.LinearBuckets(1, 2, 25),
+		},
+		[]string{"status"},
+	)
+
+	ArchiveEntriesDuration = prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Namespace: "miniflux",
+			Name:      "archive_entries_duration",
+			Help:      "Archive entries duration",
+			Buckets:   prometheus.LinearBuckets(1, 2, 30),
+		},
+		[]string{"status"},
+	)
+
+	usersGauge = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Namespace: "miniflux",
+			Name:      "users",
+			Help:      "Number of users",
+		},
+	)
+
+	feedsGauge = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Namespace: "miniflux",
+			Name:      "feeds",
+			Help:      "Number of feeds by status",
+		},
+		[]string{"status"},
+	)
+
+	brokenFeedsGauge = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Namespace: "miniflux",
+			Name:      "broken_feeds",
+			Help:      "Number of broken feeds",
+		},
+	)
+
+	entriesGauge = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Namespace: "miniflux",
+			Name:      "entries",
+			Help:      "Number of entries by status",
+		},
+		[]string{"status"},
+	)
+)
+
+// Collector represents a metric collector.
+type Collector struct {
+	store           *storage.Storage
+	refreshInterval int
+}
+
+// NewCollector initializes a new metric collector.
+func NewCollector(store *storage.Storage, refreshInterval int) *Collector {
+	prometheus.MustRegister(BackgroundFeedRefreshDuration)
+	prometheus.MustRegister(ScraperRequestDuration)
+	prometheus.MustRegister(ArchiveEntriesDuration)
+	prometheus.MustRegister(usersGauge)
+	prometheus.MustRegister(feedsGauge)
+	prometheus.MustRegister(brokenFeedsGauge)
+	prometheus.MustRegister(entriesGauge)
+
+	return &Collector{store, refreshInterval}
+}
+
+// GatherStorageMetrics polls the database to fetch metrics.
+func (c *Collector) GatherStorageMetrics() {
+	for range time.Tick(time.Duration(c.refreshInterval) * time.Second) {
+		logger.Debug("[Metric] Collecting database metrics")
+
+		usersGauge.Set(float64(c.store.CountUsers()))
+		brokenFeedsGauge.Set(float64(c.store.CountAllFeedsWithErrors()))
+
+		feedsCount := c.store.CountAllFeeds()
+		for status, count := range feedsCount {
+			feedsGauge.WithLabelValues(status).Set(float64(count))
+		}
+
+		entriesCount := c.store.CountAllEntries()
+		for status, count := range entriesCount {
+			entriesGauge.WithLabelValues(status).Set(float64(count))
+		}
+	}
+}