- Add metrics exporter for the workers

- Add metrics for the request duration and request count
- Add tests

Signed-off-by: Valery Piashchynski <[email protected]>

2 files changed, 104 insertions, 3 deletions

diff --git a/plugins/http/metrics.go b/plugins/http/metrics.go
new file mode 100644
index 00000000..d7a9110b
--- /dev/null
+++ b/plugins/http/metrics.go
@@ -0,0 +1,92 @@
+package http
+
+import (
+	"strconv"
+
+	"github.com/prometheus/client_golang/prometheus"
+	handler "github.com/spiral/roadrunner/v2/pkg/worker_handler"
+)
+
+func (p *Plugin) MetricsCollector() []prometheus.Collector {
+	// p - implements Exporter interface (workers)
+	// other - request duration and count
+	return []prometheus.Collector{p, p.requestsExporter.requestDuration, p.requestsExporter.requestCounter}
+}
+
+func (p *Plugin) metricsCallback(event interface{}) {
+	switch e := event.(type) {
+	case handler.ResponseEvent:
+		p.requestsExporter.requestCounter.With(prometheus.Labels{
+			"status": strconv.Itoa(e.Response.Status),
+		}).Inc()
+
+		p.requestsExporter.requestDuration.With(prometheus.Labels{
+			"status": strconv.Itoa(e.Response.Status),
+		}).Observe(e.Elapsed().Seconds())
+	case handler.ErrorEvent:
+		p.requestsExporter.requestCounter.With(prometheus.Labels{
+			"status": "500",
+		}).Inc()
+
+		p.requestsExporter.requestDuration.With(prometheus.Labels{
+			"status": "500",
+		}).Observe(e.Elapsed().Seconds())
+	}
+}
+
+type workersExporter struct {
+	wm            *prometheus.Desc
+	workersMemory uint64
+}
+
+func newWorkersExporter() *workersExporter {
+	return &workersExporter{
+		wm:            prometheus.NewDesc("rr_http_workers_memory_bytes", "Memory usage by HTTP workers.", nil, nil),
+		workersMemory: 0,
+	}
+}
+
+func (p *Plugin) Describe(d chan<- *prometheus.Desc) {
+	// send description
+	d <- p.workersExporter.wm
+}
+
+func (p *Plugin) Collect(ch chan<- prometheus.Metric) {
+	// get the copy of the processes
+	workers := p.Workers()
+
+	// cumulative RSS memory in bytes
+	var cum uint64
+
+	// collect the memory
+	for i := 0; i < len(workers); i++ {
+		cum += workers[i].MemoryUsage
+	}
+
+	// send the values to the prometheus
+	ch <- prometheus.MustNewConstMetric(p.workersExporter.wm, prometheus.GaugeValue, float64(cum))
+}
+
+type requestsExporter struct {
+	requestCounter  *prometheus.CounterVec
+	requestDuration *prometheus.HistogramVec
+}
+
+func newRequestsExporter() *requestsExporter {
+	return &requestsExporter{
+		requestCounter: prometheus.NewCounterVec(
+			prometheus.CounterOpts{
+				Name: "rr_http_request_total",
+				Help: "Total number of handled http requests after server restart.",
+			},
+			[]string{"status"},
+		),
+		requestDuration: prometheus.NewHistogramVec(
+			prometheus.HistogramOpts{
+				Name: "rr_http_request_duration_seconds",
+				Help: "HTTP request duration.",
+			},
+			[]string{"status"},
+		),
+	}
+}
diff --git a/plugins/http/plugin.go b/plugins/http/plugin.go
index ba83344a..bec01ac3 100644
--- a/plugins/http/plugin.go
+++ b/plugins/http/plugin.go
@@ -62,6 +62,10 @@ type Plugin struct {
 	// servers RR handler
 	handler *handler.Handler
 
+	// metrics
+	workersExporter  *workersExporter
+	requestsExporter *requestsExporter
+
 	// servers
 	http  *http.Server
 	https *http.Server
@@ -102,6 +106,11 @@ func (p *Plugin) Init(cfg config.Configurer, rrLogger logger.Logger, server serv
 		p.cfg.Env = make(map[string]string)
 	}
 
+	// initialize workersExporter
+	p.workersExporter = newWorkersExporter()
+	// initialize requests exporter
+	p.requestsExporter = newRequestsExporter()
+
 	p.cfg.Env[RrMode] = "http"
 	p.server = server
 
@@ -159,7 +168,7 @@ func (p *Plugin) serve(errCh chan error) {
 		return
 	}
 
-	p.handler.AddListener(p.logCallback)
+	p.handler.AddListener(p.logCallback, p.metricsCallback)
 
 	if p.cfg.EnableHTTP() {
 		if p.cfg.EnableH2C() {
@@ -341,7 +350,7 @@ func (p *Plugin) Reset() error {
 	}
 
 	p.log.Info("HTTP handler listeners successfully re-added")
-	p.handler.AddListener(p.logCallback)
+	p.handler.AddListener(p.logCallback, p.metricsCallback)
 
 	p.log.Info("HTTP plugin successfully restarted")
 	return nil
@@ -386,7 +395,7 @@ func (p *Plugin) Ready() status.Status {
 	workers := p.workers()
 	for i := 0; i < len(workers); i++ {
 		// If state of the worker is ready (at least 1)
-		// we assume, that plugin'p worker pool is ready
+		// we assume, that plugin's worker pool is ready
 		if workers[i].State().Value() == worker.StateReady {
 			return status.Status{
 				Code: http.StatusOK,