Adds readiness and liveness notifications for systemd

filtra_exporter.go

@@ -6,6 +6,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/coreos/go-systemd/daemon"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	log "github.com/sirupsen/logrus"
@@ -177,12 +178,22 @@ func main() {
 		log.SetLevel(log.DebugLevel)
 	}
 
+	// This is used to send systemd readiness notification
+	readyToServe := false
+
 	// Start go routine that updates values continously in the background
 	go func() {
 		for {
 			log.Info("Updating metrics from Github: %", time.Now())
 			updatePrometheusMetrics(FetchAllIssues())
 
+			// Sending readiness notication to systemd
+			if !readyToServe {
+				readyToServe = true
+				log.Debug("Sending systemd notification: READY=1")
+				daemon.SdNotify(false, "READY=1")
+			}
+
 			// Sleeping for some time, so that we don't update constantly
 			// and run into the request limit of Github.
 			log.Info("Update finished: %", time.Now())
@@ -191,8 +202,30 @@ func main() {
 		}
 	}()
 
+	// Start Go routine for systemd watchdog
+	go func() {
+		interval, err := daemon.SdWatchdogEnabled(false)
+		if err != nil || interval == 0 {
+			log.Debug("systemd watchdog not enabled")
+			return
+		}
+		for {
+			_, err := http.Get("http://127.0.0.1:8080")
+			if err == nil {
+				log.Debug("Sending systemd notification: WATCHDOG=1")
+				daemon.SdNotify(false, "WATCHDOG=1")
+			} else {
+				log.Error("Liveness check failed. Not sending notification for systemd watchdog")
+			}
+			time.Sleep(interval / 3)
+		}
+	}()
+
 	// Start the websever
 	http.Handle("/metrics", promhttp.Handler())
 	log.Info("Beginning to serve on port :8080")
-	log.Fatal(http.ListenAndServe(":8080", nil))
+	err := http.ListenAndServe(":8080", nil)
+	if err != nil {
+		log.Panic(err)
+	}
 }

go.mod

@@ -4,6 +4,7 @@ require (
 	github.com/BurntSushi/toml v0.3.1
 	github.com/brejoc/githubv4 v0.0.0-20190628081146-ff7a0d1c9aa4
 	github.com/brejoc/graphql v0.0.0-20190628081354-06d07f6a803c // indirect
+	github.com/coreos/go-systemd v0.0.0-20190620071333-e64a0ec8b42a
 	github.com/prometheus/client_golang v1.0.0
 	github.com/sirupsen/logrus v1.4.2
 	golang.org/x/net v0.0.0-20190628185345-da137c7871d7 // indirect

go.sum

@@ -10,6 +10,8 @@ github.com/brejoc/githubv4 v0.0.0-20190628081146-ff7a0d1c9aa4 h1:iVjQgCwcxfMxkeq
 github.com/brejoc/githubv4 v0.0.0-20190628081146-ff7a0d1c9aa4/go.mod h1:uGE3ZVEmsyK+I6jG0Zveu92rP5FRoggAErP/uYm0jCA=
 github.com/brejoc/graphql v0.0.0-20190628081354-06d07f6a803c h1:tVKvtFD4lhxGQ8er8G48V1SZBN5pncPFq2gppY1NHGo=
 github.com/brejoc/graphql v0.0.0-20190628081354-06d07f6a803c/go.mod h1:1suXv94t50OvWZJZNiVJEc3uCE3TmMo0RpE2Z8qLo+4=
+github.com/coreos/go-systemd v0.0.0-20190620071333-e64a0ec8b42a h1:W8b4lQ4tFF21aspRGoBuCNV6V2fFJBF+pm1J6OY8Lys=
+github.com/coreos/go-systemd v0.0.0-20190620071333-e64a0ec8b42a/go.mod h1:F5haX7vjVVG0kc13fIWeqUViNPyEJxv/OmvnBo0Yme4=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=