timeout context for fetching jitsi stats and a fetch error metric

README.md

@@ -3,4 +3,26 @@
 [![Build Status](https://cloud.drone.io/api/badges/xsteadfastx/jitsiexporter/status.svg)](https://cloud.drone.io/xsteadfastx/jitsiexporter)
 [![Docker Repository on Quay](https://quay.io/repository/xsteadfastx/jitsiexporter/status "Docker Repository on Quay")](https://quay.io/repository/xsteadfastx/jitsiexporter)
 
-a jitsi meet prometheus exporter
+A Jitsi meet prometheus exporter.
+
+        Usage of ./jitsiexporter_linux_amd64:
+          -debug
+                Enable debug.
+          -host string
+                Host to listen on. (default "localhost")
+          -interval duration
+                Seconds to wait before scraping. (default 30s)
+          -port int
+                Port to listen on. (default 9700)
+          -url string
+                URL of Jitsi Videobridge Colibri Stats.
+          -version
+                Prints version.
+
+## Usage
+
+For a docker based setup, you can use the docker image [quay.io/xsteadfastx/jitsiexporter](https://quay.io/repository/xsteadfastx/jitsiexporter).
+
+1. [Enable](https://github.com/jitsi/jitsi-videobridge/blob/master/doc/statistics.md) `/colibri/stats` for the Jitsi videobridge. When you use the Jitsi docker setup use environment variable `JVB_ENABLE_APIS=rest,colibri`.
+2. Be sure that the exporter and the videobridge API can communicate. In the docker Jitsi setup: Add the `jitsiexporter` to the `jitsi-meet_meet.jitsi`-network. The url would be `http://jitsi-meet_jvb_1:8080`.
+3. A failed scrape metric is exporter as `jitsi_fetch_errors`.

cmd/jitsiexporter/main.go

@@ -15,7 +15,7 @@ func main() {
 	ver := flag.Bool("version", false, "Prints version.")
 	url := flag.String("url", "", "URL of Jitsi Videobridge Colibri Stats.")
 	debug := flag.Bool("debug", false, "Enable debug.")
-	interval := flag.Duration("interval", 10*time.Second, "Seconds to wait before scraping.") // nolint: gomnd
+	interval := flag.Duration("interval", 30*time.Second, "Seconds to wait before scraping.") // nolint: gomnd
 	port := flag.Int("port", 9700, "Port to listen on.")
 	host := flag.String("host", "localhost", "Host to listen on.")
 	flag.Parse()

jitsiexporter.go

@@ -1,6 +1,7 @@
 package jitsiexporter
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"net/http"
@@ -20,17 +21,32 @@ type Metric struct {
 }
 
 type Metrics struct {
-	Metrics map[string]Metric
-	URL     string
-	Stater  Stater
-	mux     sync.Mutex
+	Metrics  map[string]Metric
+	URL      string
+	Stater   Stater
+	mux      sync.Mutex
+	Errors   prometheus.Counter
+	Interval time.Duration
 }
 
-func (m *Metrics) Update() {
-	now := m.Stater.Now(m.URL)
+func (m *Metrics) Update() error {
+	m.mux.Lock()
+	defer m.mux.Unlock()
+
+	now, err := m.Stater.Now(m.URL)
+
+	if err != nil {
+		m.Errors.Inc()
+
+		for _, i := range m.Metrics {
+			prometheus.Unregister(i.Gauge)
+		}
+
+		return err
+	}
+
 	log.Debug(now)
 
-	m.mux.Lock()
 	for k, v := range now {
 		fieldLogger := log.WithFields(log.Fields{"key": k})
 
@@ -65,48 +81,99 @@ func (m *Metrics) Update() {
 			continue
 		}
 	}
-	m.mux.Unlock()
+
+	return nil
+}
+
+type Response struct {
+	Resp  *http.Response
+	Error error
+}
+
+func get(ctx context.Context, url string, resp chan Response) {
+	req, err := http.NewRequest("GET", url, nil)
+	if err != nil {
+		resp <- Response{Resp: nil, Error: err}
+		return
+	}
+
+	client := http.DefaultClient
+
+	res, err := client.Do(req.WithContext(ctx)) // nolint:bodyclose
+	if err != nil {
+		resp <- Response{Resp: nil, Error: err}
+	}
+
+	resp <- Response{Resp: res, Error: nil}
 }
 
 type Stater interface {
-	Now(url string) map[string]interface{}
+	Now(url string) (map[string]interface{}, error)
 }
 
 type colibri struct{}
 
-func (c colibri) Now(url string) map[string]interface{} {
+func (c colibri) Now(url string) (map[string]interface{}, error) {
 	s := make(map[string]interface{})
-	resp, err := http.Get(url) // nolint:gosec
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second) // nolint:gomnd
+
+	defer cancel()
+
+	res := make(chan Response)
+
+	var resp *http.Response
+
+	var err error
+
+	go get(ctx, url, res)
+
+	select {
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	case r := <-res:
+		err = r.Error
+		resp = r.Resp
+
+		defer resp.Body.Close()
+	}
 
 	if err != nil {
-		log.Fatal(err)
+		return nil, err
 	}
 
-	defer resp.Body.Close()
 	err = json.NewDecoder(resp.Body).Decode(&s)
 
 	if err != nil {
-		log.Fatal(err)
+		return nil, err
 	}
 
-	return s
+	return s, nil
 }
 
 func collect(m *Metrics) {
 	for {
-		m.Update()
-		time.Sleep(30 * time.Second) // nolint:gomnd
+		err := m.Update()
+		if err != nil {
+			log.Error(err)
+		}
+
+		time.Sleep(m.Interval) // nolint:gomnd
 	}
 }
 
 func Serve(url string, debug bool, interval time.Duration, port int, host string) {
 	s := colibri{}
+	e := prometheus.NewCounter(prometheus.CounterOpts{Name: "jitsi_fetch_errors"})
 	metrics := &Metrics{
-		URL:     url,
-		Stater:  s,
-		Metrics: make(map[string]Metric),
+		URL:      url,
+		Stater:   s,
+		Metrics:  make(map[string]Metric),
+		Errors:   e,
+		Interval: interval,
 	}
 
+	prometheus.MustRegister(e)
+
 	if debug {
 		log.SetLevel(log.DebugLevel)
 	}

main_test.go

@@ -16,7 +16,7 @@ func TestUpdate(t *testing.T) {
 	s["bar"] = 1           // nolint:gomnd
 	s["zonk"] = float64(1) // nolint:gomnd
 	mockStater := &MockStater{}
-	mockStater.On("Now", "http://foo.tld").Return(s)
+	mockStater.On("Now", "http://foo.tld").Return(s, nil)
 
 	m := &Metrics{
 		URL:     "http://foo.tld",

mock_Stater.go

@@ -10,7 +10,7 @@ type MockStater struct {
 }
 
 // Now provides a mock function with given fields: url
-func (_m *MockStater) Now(url string) map[string]interface{} {
+func (_m *MockStater) Now(url string) (map[string]interface{}, error) {
 	ret := _m.Called(url)
 
 	var r0 map[string]interface{}
@@ -22,5 +22,12 @@ func (_m *MockStater) Now(url string) map[string]interface{} {
 		}
 	}
 
-	return r0
+	var r1 error
+	if rf, ok := ret.Get(1).(func(string) error); ok {
+		r1 = rf(url)
+	} else {
+		r1 = ret.Error(1)
+	}
+
+	return r0, r1
 }