Add metric to track collector duration

And register Go and process collectors too.

host/host_collector.go

@@ -37,15 +37,16 @@ func init() {
 
 // HostCollector collects host statistics from oVirt
 type HostCollector struct {
-	client         *api.Client
-	metrics        []prometheus.Metric
-	collectNetwork bool
-	mutex          sync.Mutex
+	client          *api.Client
+	collectDuration prometheus.Observer
+	metrics         []prometheus.Metric
+	collectNetwork  bool
+	mutex           sync.Mutex
 }
 
 // NewCollector creates a new collector
-func NewCollector(client *api.Client, collectNetwork bool) prometheus.Collector {
-	return &HostCollector{client: client, collectNetwork: collectNetwork}
+func NewCollector(client *api.Client, collectNetwork bool, collectDuration prometheus.Observer) prometheus.Collector {
+	return &HostCollector{client: client, collectNetwork: collectNetwork, collectDuration: collectDuration}
 }
 
 // Collect implements Prometheus Collector interface
@@ -75,6 +76,9 @@ func (c *HostCollector) getMetrics() []prometheus.Metric {
 }
 
 func (c *HostCollector) retrieveMetrics() {
+	timer := prometheus.NewTimer(c.collectDuration)
+	defer timer.ObserveDuration()
+
 	h := Hosts{}
 	err := c.client.GetAndParse("hosts", &h)
 	if err != nil {

main.go

@@ -28,6 +28,15 @@ var (
 	withSnapshots   = flag.Bool("with-snapshots", true, "Collect snapshot metrics (can be time consuming in some cases)")
 	withNetwork     = flag.Bool("with-network", true, "Collect network metrics (can be time consuming in some cases)")
 	debug           = flag.Bool("debug", false, "Show verbose output (e.g. body of each response received from API)")
+
+	collectorDuration = prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:    "ovirt_collectors_duration",
+			Help:    "Histogram of latencies for metric collectors.",
+			Buckets: []float64{.1, .2, .4, 1, 3, 8, 20, 60},
+		},
+		[]string{"collector"},
+	)
 )
 
 func init() {
@@ -77,8 +86,13 @@ func startServer() {
 	}
 	defer client.Close()
 
+	reg := prometheus.NewRegistry()
+	reg.MustRegister(prometheus.NewProcessCollector(prometheus.ProcessCollectorOpts{}))
+	reg.MustRegister(prometheus.NewGoCollector())
+	reg.MustRegister(collectorDuration)
+
 	http.HandleFunc(*metricsPath, func(w http.ResponseWriter, r *http.Request) {
-		handleMetricsRequest(w, r, client)
+		handleMetricsRequest(w, r, client, reg)
 	})
 
 	log.Infof("Listening for %s on %s", *metricsPath, *listenAddress)
@@ -104,13 +118,19 @@ func connectAPI() (*api.Client, error) {
 	return client, err
 }
 
-func handleMetricsRequest(w http.ResponseWriter, r *http.Request, client *api.Client) {
+func handleMetricsRequest(w http.ResponseWriter, r *http.Request, client *api.Client, appReg *prometheus.Registry) {
 	reg := prometheus.NewRegistry()
-	reg.MustRegister(vm.NewCollector(client, *withSnapshots, *withNetwork))
-	reg.MustRegister(host.NewCollector(client, *withNetwork))
-	reg.MustRegister(storagedomain.NewCollector(client))
+	reg.MustRegister(vm.NewCollector(client, *withSnapshots, *withNetwork, collectorDuration.WithLabelValues("vm")))
+	reg.MustRegister(host.NewCollector(client, *withNetwork, collectorDuration.WithLabelValues("host")))
+	reg.MustRegister(storagedomain.NewCollector(client, collectorDuration.WithLabelValues("storage")))
+
+	multiRegs := prometheus.Gatherers{
+		reg,
+		appReg,
+	}
 
-	promhttp.HandlerFor(reg, promhttp.HandlerOpts{
+	promhttp.HandlerFor(multiRegs, promhttp.HandlerOpts{
 		ErrorLog:      log.NewErrorLogger(),
-		ErrorHandling: promhttp.ContinueOnError}).ServeHTTP(w, r)
+		ErrorHandling: promhttp.ContinueOnError,
+		Registry:      appReg}).ServeHTTP(w, r)
 }

storagedomain/storagedomain_collector.go

@@ -28,16 +28,20 @@ func init() {
 
 // StorageDomainCollector collects storage domain statistics from oVirt
 type StorageDomainCollector struct {
-	client *api.Client
+	client          *api.Client
+	collectDuration prometheus.Observer
 }
 
 // NewCollector creates a new collector
-func NewCollector(client *api.Client) prometheus.Collector {
-	return &StorageDomainCollector{client: client}
+func NewCollector(client *api.Client, collectDuration prometheus.Observer) prometheus.Collector {
+	return &StorageDomainCollector{client: client, collectDuration: collectDuration}
 }
 
 // Collect implements Prometheus Collector interface
 func (c *StorageDomainCollector) Collect(ch chan<- prometheus.Metric) {
+	timer := prometheus.NewTimer(c.collectDuration)
+	defer timer.ObserveDuration()
+
 	s := StorageDomains{}
 	err := c.client.GetAndParse("storagedomains", &s)
 	if err != nil {

vm/vm_collector.go

@@ -41,20 +41,22 @@ func init() {
 	maxSnapshotAge = prometheus.NewDesc(prefix+"snapshot_max_age_seconds", "Age of the oldest snapshot in seconds", labelNames, nil)
 	minSnapshotAge = prometheus.NewDesc(prefix+"snapshot_min_age_seconds", "Age of the newest snapshot in seconds", labelNames, nil)
 	illegalImages = prometheus.NewDesc(prefix+"illegal_images", "Health status of the disks attatched to the VM (1 if one or more disk is in illegal state)", labelNames, nil)
+
 }
 
 // VMCollector collects virtual machine statistics from oVirt
 type VMCollector struct {
 	client           *api.Client
+	collectDuration  prometheus.Observer
 	metrics          []prometheus.Metric
 	collectSnapshots bool
 	collectNetwork   bool
 	mutex            sync.Mutex
 }
 
 // NewCollector creates a new collector
-func NewCollector(client *api.Client, collectSnaphots, collectNetwork bool) prometheus.Collector {
-	return &VMCollector{client: client, collectSnapshots: collectSnaphots, collectNetwork: collectNetwork}
+func NewCollector(client *api.Client, collectSnaphots, collectNetwork bool, collectDuration prometheus.Observer) prometheus.Collector {
+	return &VMCollector{client: client, collectSnapshots: collectSnaphots, collectNetwork: collectNetwork, collectDuration: collectDuration}
 }
 
 // Collect implements Prometheus Collector interface
@@ -84,6 +86,9 @@ func (c *VMCollector) getMetrics() []prometheus.Metric {
 }
 
 func (c *VMCollector) retrieveMetrics() {
+	timer := prometheus.NewTimer(c.collectDuration)
+	defer timer.ObserveDuration()
+
 	v := VMs{}
 	err := c.client.GetAndParse("vms", &v)
 	if err != nil {