Add Prometheus exporter

Makefile

@@ -92,7 +92,7 @@ windows-x86: generate
 	@ GOOS=windows GOARCH=386 go build -ldflags=$(LD_FLAGS) -o $(APP)-windows-x86 main.go
 
 run: generate
-	@ go run main.go -debug
+	@ LOG_DATE_TIME=1 go run main.go -debug
 
 clean:
 	@ rm -f $(APP)-* $(APP)

cli/daemon.go

@@ -9,12 +9,12 @@ import (
 	"net/http"
 	"os"
 	"os/signal"
-	"runtime"
 	"syscall"
 	"time"
 
 	"miniflux.app/config"
 	"miniflux.app/logger"
+	"miniflux.app/metric"
 	"miniflux.app/reader/feed"
 	"miniflux.app/service/httpd"
 	"miniflux.app/service/scheduler"
@@ -32,8 +32,6 @@ func startDaemon(store *storage.Storage) {
 	feedHandler := feed.NewFeedHandler(store)
 	pool := worker.NewPool(feedHandler, config.Opts.WorkerPoolSize())
 
-	go showProcessStatistics()
-
 	if config.Opts.HasSchedulerService() && !config.Opts.HasMaintenanceMode() {
 		scheduler.Serve(store, pool)
 	}
@@ -43,6 +41,11 @@ func startDaemon(store *storage.Storage) {
 		httpServer = httpd.Serve(store, pool, feedHandler)
 	}
 
+	if config.Opts.HasMetricsCollector() {
+		collector := metric.NewCollector(store, config.Opts.MetricsRefreshInterval())
+		go collector.GatherStorageMetrics()
+	}
+
 	<-stop
 	logger.Info("Shutting down the process...")
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
@@ -54,14 +57,3 @@ func startDaemon(store *storage.Storage) {
 
 	logger.Info("Process gracefully stopped")
 }
-
-func showProcessStatistics() {
-	for {
-		var m runtime.MemStats
-		runtime.ReadMemStats(&m)
-		logger.Debug("Sys=%vK, InUse=%vK, HeapInUse=%vK, StackSys=%vK, StackInUse=%vK, GoRoutines=%d, NumCPU=%d",
-			m.Sys/1024, (m.Sys-m.HeapReleased)/1024, m.HeapInuse/1024, m.StackSys/1024, m.StackInuse/1024,
-			runtime.NumGoroutine(), runtime.NumCPU())
-		time.Sleep(30 * time.Second)
-	}
-}

config/options.go

@@ -56,6 +56,9 @@ const (
 	defaultAuthProxyUserCreation              = false
 	defaultMaintenanceMode                    = false
 	defaultMaintenanceMessage                 = "Miniflux is currently under maintenance"
+	defaultMetricsCollector                   = false
+	defaultMetricsRefreshInterval             = 60
+	defaultMetricsAllowedNetworks             = "127.0.0.1/8"
 )
 
 // Options contains configuration options.
@@ -106,6 +109,9 @@ type Options struct {
 	authProxyUserCreation              bool
 	maintenanceMode                    bool
 	maintenanceMessage                 string
+	metricsCollector                   bool
+	metricsRefreshInterval             int
+	metricsAllowedNetworks             []string
 }
 
 // NewOptions returns Options with default values.
@@ -155,6 +161,9 @@ func NewOptions() *Options {
 		authProxyUserCreation:              defaultAuthProxyUserCreation,
 		maintenanceMode:                    defaultMaintenanceMode,
 		maintenanceMessage:                 defaultMaintenanceMessage,
+		metricsCollector:                   defaultMetricsCollector,
+		metricsRefreshInterval:             defaultMetricsRefreshInterval,
+		metricsAllowedNetworks:             []string{defaultMetricsAllowedNetworks},
 	}
 }
 
@@ -398,6 +407,21 @@ func (o *Options) IsAuthProxyUserCreationAllowed() bool {
 	return o.authProxyUserCreation
 }
 
+// HasMetricsCollector returns true if metrics collection is enabled.
+func (o *Options) HasMetricsCollector() bool {
+	return o.metricsCollector
+}
+
+// MetricsRefreshInterval returns the refresh interval in seconds.
+func (o *Options) MetricsRefreshInterval() int {
+	return o.metricsRefreshInterval
+}
+
+// MetricsAllowedNetworks returns the list of networks allowed to connect to the metrics endpoint.
+func (o *Options) MetricsAllowedNetworks() []string {
+	return o.metricsAllowedNetworks
+}
+
 func (o *Options) String() string {
 	var builder strings.Builder
 	builder.WriteString(fmt.Sprintf("LOG_DATE_TIME: %v\n", o.logDateTime))
@@ -446,5 +470,8 @@ func (o *Options) String() string {
 	builder.WriteString(fmt.Sprintf("AUTH_PROXY_USER_CREATION: %v\n", o.authProxyUserCreation))
 	builder.WriteString(fmt.Sprintf("MAINTENANCE_MODE: %v\n", o.maintenanceMode))
 	builder.WriteString(fmt.Sprintf("MAINTENANCE_MESSAGE: %v\n", o.maintenanceMessage))
+	builder.WriteString(fmt.Sprintf("METRICS_COLLECTOR: %v\n", o.metricsCollector))
+	builder.WriteString(fmt.Sprintf("METRICS_REFRESH_INTERVAL: %v\n", o.metricsRefreshInterval))
+	builder.WriteString(fmt.Sprintf("METRICS_ALLOWED_NETWORKS: %v\n", o.metricsAllowedNetworks))
 	return builder.String()
 }

config/parser.go

@@ -178,6 +178,12 @@ func (p *Parser) parseLines(lines []string) (err error) {
 			p.opts.maintenanceMode = parseBool(value, defaultMaintenanceMode)
 		case "MAINTENANCE_MESSAGE":
 			p.opts.maintenanceMessage = parseString(value, defaultMaintenanceMessage)
+		case "METRICS_COLLECTOR":
+			p.opts.metricsCollector = parseBool(value, defaultMetricsCollector)
+		case "METRICS_REFRESH_INTERVAL":
+			p.opts.metricsRefreshInterval = parseInt(value, defaultMetricsRefreshInterval)
+		case "METRICS_ALLOWED_NETWORKS":
+			p.opts.metricsAllowedNetworks = parseStringList(value, []string{defaultMetricsAllowedNetworks})
 		}
 	}
 
@@ -244,6 +250,20 @@ func parseString(value string, fallback string) string {
 	return value
 }
 
+func parseStringList(value string, fallback []string) []string {
+	if value == "" {
+		return fallback
+	}
+
+	var strList []string
+	items := strings.Split(value, ",")
+	for _, item := range items {
+		strList = append(strList, strings.TrimSpace(item))
+	}
+
+	return strList
+}
+
 func readSecretFile(filename, fallback string) string {
 	data, err := ioutil.ReadFile(filename)
 	if err != nil {

go.mod

@@ -5,18 +5,21 @@ module miniflux.app
 require (
 	github.com/PuerkitoBio/goquery v1.5.1
 	github.com/coreos/go-oidc v2.2.1+incompatible
-	github.com/golang/protobuf v1.4.0 // indirect
 	github.com/gorilla/mux v1.8.0
 	github.com/lib/pq v1.8.0
 	github.com/pquerna/cachecontrol v0.0.0-20180517163645-1555304b9b35 // indirect
+	github.com/prometheus/client_golang v1.7.1
+	github.com/prometheus/common v0.14.0 // indirect
+	github.com/prometheus/procfs v0.2.0 // indirect
 	github.com/rylans/getlang v0.0.0-20200505200108-4c3188ff8a2d
 	github.com/stretchr/testify v1.6.1 // indirect
 	github.com/tdewolff/minify/v2 v2.9.5 // indirect
-	golang.org/x/crypto v0.0.0-20200423211502-4bdfaf469ed5
-	golang.org/x/net v0.0.0-20200425230154-ff2c4b7c35a0
+	golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9
+	golang.org/x/net v0.0.0-20200625001655-4c5254603344
 	golang.org/x/oauth2 v0.0.0-20200107190931-bf48bf16ab8d
-	golang.org/x/sys v0.0.0-20200724161237-0e2f3a69832c // indirect
+	golang.org/x/sys v0.0.0-20200926100807-9d91bd62050c // indirect
 	google.golang.org/appengine v1.6.6 // indirect
+	google.golang.org/protobuf v1.25.0 // indirect
 	gopkg.in/square/go-jose.v2 v2.5.0 // indirect
 )