feat: add config file

Signed-off-by: Rory Z <16801068+Rory-Z@users.noreply.github.com>

Dockerfile

@@ -14,6 +14,7 @@ FROM quay.io/prometheus/busybox:latest
 LABEL maintainer="EMQX"
 
 COPY --from=builder /workspace/emqx-exporter /bin/emqx-exporter
+COPY config/example/config.yaml /etc/emqx-exporter/config.yaml
 
 EXPOSE      8085
 USER        nobody

config/config.go

@@ -0,0 +1,91 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"sync"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+
+	yaml "gopkg.in/yaml.v3"
+)
+
+type Config struct {
+	Probes []Probe `yaml:"probes"`
+}
+
+type Probe struct {
+	Target   string `yaml:"target"`
+	Scheme   string `yaml:"scheme,omitempty"`
+	ClientID string `yaml:"client_id,omitempty"`
+	Username string `yaml:"username,omitempty"`
+	Password string `yaml:"password,omitempty"`
+	Topic    string `yaml:"topic,omitempty"`
+	QoS      byte   `yaml:"qos,omitempty"`
+}
+
+type SafeConfig struct {
+	sync.RWMutex
+	C                   *Config
+	configReloadSuccess prometheus.Gauge
+	configReloadSeconds prometheus.Gauge
+}
+
+func NewSafeConfig(reg prometheus.Registerer) *SafeConfig {
+	configReloadSuccess := promauto.With(reg).NewGauge(prometheus.GaugeOpts{
+		Namespace: "emqx_exporter",
+		Name:      "config_last_reload_successful",
+		Help:      "EMQX exporter config loaded successfully.",
+	})
+
+	configReloadSeconds := promauto.With(reg).NewGauge(prometheus.GaugeOpts{
+		Namespace: "emqx_exporter",
+		Name:      "config_last_reload_success_timestamp_seconds",
+		Help:      "Timestamp of the last successful configuration reload.",
+	})
+	return &SafeConfig{C: &Config{}, configReloadSuccess: configReloadSuccess, configReloadSeconds: configReloadSeconds}
+}
+
+func (sc *SafeConfig) ReloadConfig(confFile string) (err error) {
+	var c = &Config{}
+	defer func() {
+		if err != nil {
+			sc.configReloadSuccess.Set(0)
+		} else {
+			sc.configReloadSuccess.Set(1)
+			sc.configReloadSeconds.SetToCurrentTime()
+		}
+	}()
+
+	yamlReader, err := os.Open(confFile)
+	if err != nil {
+		return fmt.Errorf("error reading config file: %s", err)
+	}
+	defer yamlReader.Close()
+	decoder := yaml.NewDecoder(yamlReader)
+	decoder.KnownFields(true)
+
+	if err = decoder.Decode(c); err != nil {
+		return fmt.Errorf("error parsing config file: %s", err)
+	}
+
+	for index, probe := range c.Probes {
+		if probe.Scheme == "" {
+			probe.Scheme = "tcp"
+		}
+		if probe.ClientID == "" {
+			probe.ClientID = "emqx_exporter_probe"
+		}
+		if probe.Topic == "" {
+			probe.Topic = "emqx_exporter_probe"
+		}
+		c.Probes[index] = probe
+	}
+
+	sc.Lock()
+	sc.C = c
+	sc.Unlock()
+
+	return nil
+}

config/example/config.yaml

@@ -0,0 +1,8 @@
+probes:
+  - target: broker.emqx.io:1883
+    scheme:
+    client_id:
+    username:
+    password:
+    topic:
+    qos:

go.mod

@@ -43,4 +43,5 @@ require (
 	google.golang.org/appengine v1.6.7 // indirect
 	google.golang.org/protobuf v1.30.0 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -106,3 +106,4 @@ gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
 gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

main.go

@@ -15,7 +15,9 @@ package main
 
 import (
 	"emqx-exporter/client"
+	"emqx-exporter/config"
 	"emqx-exporter/prober"
+
 	"fmt"
 	stdlog "log"
 	"net/http"
@@ -29,6 +31,7 @@ import (
 	promcollectors "github.com/prometheus/client_golang/prometheus/collectors"
 	"github.com/prometheus/common/promlog"
 	"github.com/prometheus/common/promlog/flag"
+	"gopkg.in/yaml.v2"
 
 	"emqx-exporter/collector"
 
@@ -112,6 +115,16 @@ func newHandler(includeExporterMetrics bool, maxRequests int, logger log.Logger)
 	}
 }
 
+var (
+	sc = config.NewSafeConfig(prometheus.DefaultRegisterer)
+
+	configFile = kingpin.Flag("config.file", "EMQX exporter configuration file.").Default("/etc/emqx-exporter/config.yaml").String()
+)
+
+func init() {
+	prometheus.MustRegister(version.NewCollector("emqx_exporter"))
+}
+
 func main() {
 	var (
 		disableExporterMetrics = kingpin.Flag(
@@ -134,10 +147,17 @@ func main() {
 	kingpin.CommandLine.UsageWriter(os.Stdout)
 	kingpin.HelpFlag.Short('h')
 	kingpin.Parse()
-	logger := promlog.New(promlogConfig)
 
+	logger := promlog.New(promlogConfig)
 	level.Info(logger).Log("msg", "Starting emqx-exporter", "version", version.Info())
 	level.Info(logger).Log("msg", "Build context", "build_context", version.BuildContext())
+
+	if err := sc.ReloadConfig(*configFile); err != nil {
+		level.Error(logger).Log("msg", "Error loading config", "err", err)
+		os.Exit(1)
+	}
+	level.Info(logger).Log("msg", "Loaded config file")
+
 	if user, err := user.Current(); err == nil && user.Uid == "0" {
 		level.Warn(logger).Log("msg", "EMQX Exporter is running as root user. This exporter is designed to run as unprivileged user, root is not required.")
 	}
@@ -147,7 +167,23 @@ func main() {
 	http.Handle("/metrics", newHandler(!*disableExporterMetrics, *maxRequests, logger))
 
 	http.HandleFunc("/probe", func(w http.ResponseWriter, r *http.Request) {
-		prober.Handler(w, r, logger)
+		sc.Lock()
+		probes := sc.C.Probes
+		sc.Unlock()
+		prober.Handler(w, r, probes, logger, nil)
+	})
+
+	http.HandleFunc("/config", func(w http.ResponseWriter, r *http.Request) {
+		sc.RLock()
+		c, err := yaml.Marshal(sc.C)
+		sc.RUnlock()
+		if err != nil {
+			level.Warn(logger).Log("msg", "Error marshalling configuration", "err", err)
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		w.Header().Set("Content-Type", "text/plain")
+		w.Write(c)
 	})
 
 	landingConfig := web.LandingConfig{
@@ -163,6 +199,10 @@ func main() {
 				Address: "/probe",
 				Text:    "Probe",
 			},
+			{
+				Address: "/config",
+				Text:    "Config",
+			},
 		},
 	}
 	landingPage, err := web.NewLandingPage(landingConfig)

prober/handler.go

@@ -1,15 +1,37 @@
 package prober
 
 import (
+	"emqx-exporter/config"
+	"fmt"
+
 	"net/http"
+	"net/url"
 	"time"
 
 	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 )
 
-func Handler(w http.ResponseWriter, r *http.Request, logger log.Logger) {
+func Handler(w http.ResponseWriter, r *http.Request, probes []config.Probe, logger log.Logger, params url.Values) {
+	var probe config.Probe
+	if params == nil {
+		params = r.URL.Query()
+	}
+	target := params.Get("target")
+	for i := 0; i < len(probes); i++ {
+		if probes[i].Target == target {
+			probe = probes[i]
+			break
+		}
+	}
+	if probe.Target == "" {
+		http.Error(w, fmt.Sprintf("Unknown probe target %q", target), http.StatusBadRequest)
+		level.Debug(logger).Log("msg", "Unknown probe target", "target", target)
+		return
+	}
+
 	probeSuccessGauge := prometheus.NewGauge(prometheus.GaugeOpts{
 		Namespace: "emqx",
 		Subsystem: "mqtt",
@@ -28,7 +50,7 @@ func Handler(w http.ResponseWriter, r *http.Request, logger log.Logger) {
 	registry.MustRegister(probeDurationGauge)
 
 	start := time.Now()
-	if ProbeMQTT(logger) {
+	if ProbeMQTT(probe, logger) {
 		probeSuccessGauge.Set(1)
 	} else {
 		probeSuccessGauge.Set(0)

prober/mqtt.go

@@ -1,6 +1,7 @@
 package prober
 
 import (
+	"emqx-exporter/config"
 	"time"
 
 	mqtt "github.com/eclipse/paho.mqtt.golang"
@@ -15,8 +16,8 @@ type MQTTProbe struct {
 
 var mqttProbe *MQTTProbe
 
-func initMQTTProbe(logger log.Logger) (*MQTTProbe, error) {
-	opt := mqtt.NewClientOptions().AddBroker("tcp://broker.emqx.io:1883").SetClientID("emqx-exporter")
+func initMQTTProbe(probe config.Probe, logger log.Logger) (*MQTTProbe, error) {
+	opt := mqtt.NewClientOptions().AddBroker(probe.Scheme + "://" + probe.Target).SetClientID(probe.ClientID).SetUsername(probe.Username).SetPassword(probe.Password)
 	opt.SetOnConnectHandler(func(c mqtt.Client) {
 		level.Info(logger).Log("msg", "Connected to MQTT broker")
 	})
@@ -30,7 +31,7 @@ func initMQTTProbe(logger log.Logger) (*MQTTProbe, error) {
 	}
 
 	var msgChan = make(chan mqtt.Message)
-	if token := c.Subscribe("emqx-exporter", 1, func(c mqtt.Client, m mqtt.Message) {
+	if token := c.Subscribe(probe.Topic, probe.QoS, func(c mqtt.Client, m mqtt.Message) {
 		msgChan <- m
 	}); token.Wait() && token.Error() != nil {
 		level.Error(logger).Log("msg", "Failed to subscribe to MQTT topic", "err", token.Error())
@@ -43,10 +44,10 @@ func initMQTTProbe(logger log.Logger) (*MQTTProbe, error) {
 	}, nil
 }
 
-func ProbeMQTT(logger log.Logger) bool {
+func ProbeMQTT(probe config.Probe, logger log.Logger) bool {
 	if mqttProbe == nil {
 		var err error
-		if mqttProbe, err = initMQTTProbe(logger); err != nil {
+		if mqttProbe, err = initMQTTProbe(probe, logger); err != nil {
 			return false
 		}
 	}
@@ -55,7 +56,7 @@ func ProbeMQTT(logger log.Logger) bool {
 		return false
 	}
 
-	if token := mqttProbe.Client.Publish("emqx-exporter", 1, false, "hello world"); token.Wait() && token.Error() != nil {
+	if token := mqttProbe.Client.Publish(probe.Topic, probe.QoS, false, "hello world"); token.Wait() && token.Error() != nil {
 		return false
 	}