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Add lifecycle api #329

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Aug 21, 2020
Merged

Add lifecycle api #329

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7 changes: 7 additions & 0 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -82,6 +82,7 @@ Also, tags without values (`#some_tag`) are not supported and will be ignored.
NOTE: Version 0.7.0 switched to the [kingpin](https://github.com/alecthomas/kingpin) flags library. With this change, flag behaviour is POSIX-ish:

* long flags start with two dashes (`--version`)
* boolean long flags are disabled by prefixing with no (`--flag-name` is true, `--no-flag-name` is false)
* multiple short flags can be combined (but there currently is only one)
* flag processing stops at the first `--`

Expand All @@ -94,6 +95,7 @@ NOTE: Version 0.7.0 switched to the [kingpin](https://github.com/alecthomas/king
--web.listen-address=":9102"
The address on which to expose the web interface
and generated Prometheus metrics.
--web.enable-lifecycle Enable shutdown and reload via HTTP request.
--web.telemetry-path="/metrics"
Path under which to expose metrics.
--statsd.listen-udp=":9125"
Expand Down Expand Up @@ -138,6 +140,11 @@ NOTE: Version 0.7.0 switched to the [kingpin](https://github.com/alecthomas/king
--version Show application version.
```

## Lifecycle API

The `statsd_exporter` has an optional lifecycle API (disabled by default) that can be used to reload or quit the exporter
by sending a `PUT` or `POST` request to the `/-/reload` or `/-/quit` endpoints.

## Tests

$ go test
Expand Down
76 changes: 51 additions & 25 deletions main.go
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Expand Up @@ -199,23 +199,12 @@ func (u uncheckedCollector) Collect(c chan<- prometheus.Metric) {
u.c.Collect(c)
}

func serveHTTP(listenAddress, metricsEndpoint string, logger log.Logger) {
http.Handle(metricsEndpoint, promhttp.Handler())
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte(`<html>
<head><title>StatsD Exporter</title></head>
<body>
<h1>StatsD Exporter</h1>
<p><a href="` + metricsEndpoint + `">Metrics</a></p>
</body>
</html>`))
})
level.Error(logger).Log("msg", http.ListenAndServe(listenAddress, nil))
func serveHTTP(mux http.Handler, listenAddress string, logger log.Logger) {
level.Error(logger).Log("msg", http.ListenAndServe(listenAddress, mux))
os.Exit(1)
}

func configReloader(fileName string, mapper *mapper.MetricMapper, cacheSize int, logger log.Logger, option mapper.CacheOption) {

func sighupConfigReloader(fileName string, mapper *mapper.MetricMapper, cacheSize int, logger log.Logger, option mapper.CacheOption) {
signals := make(chan os.Signal, 1)
signal.Notify(signals, syscall.SIGHUP)

Expand All @@ -224,15 +213,21 @@ func configReloader(fileName string, mapper *mapper.MetricMapper, cacheSize int,
level.Warn(logger).Log("msg", "Received signal but no mapping config to reload", "signal", s)
continue
}

level.Info(logger).Log("msg", "Received signal, attempting reload", "signal", s)
err := mapper.InitFromFile(fileName, cacheSize, option)
if err != nil {
level.Info(logger).Log("msg", "Error reloading config", "error", err)
configLoads.WithLabelValues("failure").Inc()
} else {
level.Info(logger).Log("msg", "Config reloaded successfully")
configLoads.WithLabelValues("success").Inc()
}

reloadConfig(fileName, mapper, cacheSize, logger, option)
}
}

func reloadConfig(fileName string, mapper *mapper.MetricMapper, cacheSize int, logger log.Logger, option mapper.CacheOption) {
err := mapper.InitFromFile(fileName, cacheSize, option)
if err != nil {
level.Info(logger).Log("msg", "Error reloading config", "error", err)
configLoads.WithLabelValues("failure").Inc()
} else {
level.Info(logger).Log("msg", "Config reloaded successfully")
configLoads.WithLabelValues("success").Inc()
}
}

Expand All @@ -253,6 +248,7 @@ func dumpFSM(mapper *mapper.MetricMapper, dumpFilename string, logger log.Logger
func main() {
var (
listenAddress = kingpin.Flag("web.listen-address", "The address on which to expose the web interface and generated Prometheus metrics.").Default(":9102").String()
enableLifecycle = kingpin.Flag("web.enable-lifecycle", "Enable shutdown and reload via HTTP request.").Default("false").Bool()
metricsEndpoint = kingpin.Flag("web.telemetry-path", "Path under which to expose metrics.").Default("/metrics").String()
statsdListenUDP = kingpin.Flag("statsd.listen-udp", "The UDP address on which to receive statsd metric lines. \"\" disables it.").Default(":9125").String()
statsdListenTCP = kingpin.Flag("statsd.listen-tcp", "The TCP address on which to receive statsd metric lines. \"\" disables it.").Default(":9125").String()
Expand Down Expand Up @@ -289,8 +285,6 @@ func main() {
level.Info(logger).Log("msg", "Accepting StatsD Traffic", "udp", *statsdListenUDP, "tcp", *statsdListenTCP, "unixgram", *statsdListenUnixgram)
level.Info(logger).Log("msg", "Accepting Prometheus Requests", "addr", *listenAddress)

go serveHTTP(*listenAddress, *metricsEndpoint, logger)

events := make(chan event.Events, *eventQueueSize)
defer close(events)
eventQueue := event.NewEventQueue(events, *eventFlushThreshold, *eventFlushInterval, eventsFlushed)
Expand Down Expand Up @@ -448,10 +442,42 @@ func main() {
return
}

mux := http.NewServeMux()
mux.Handle(*metricsEndpoint, promhttp.Handler())
mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte(`<html>
<head><title>StatsD Exporter</title></head>
<body>
<h1>StatsD Exporter</h1>
<p><a href="` + *metricsEndpoint + `">Metrics</a></p>
</body>
</html>`))
})
if *enableLifecycle {
mux.HandleFunc("/-/reload", func(w http.ResponseWriter, r *http.Request) {
if r.Method == http.MethodPut || r.Method == http.MethodPost {
if *mappingConfig == "" {
level.Warn(logger).Log("msg", "Received lifecycle api reload but no mapping config to reload")
return
}
level.Info(logger).Log("msg", "Received lifecycle api reload, attempting reload")
reloadConfig(*mappingConfig, mapper, *cacheSize, logger, cacheOption)
}
})
mux.HandleFunc("/-/quit", func(w http.ResponseWriter, r *http.Request) {
if r.Method == http.MethodPut || r.Method == http.MethodPost {
level.Info(logger).Log("msg", "Received lifecycle api quit, exiting")
os.Exit(0)
}
})
}

go serveHTTP(mux, *listenAddress, logger)

signals := make(chan os.Signal, 1)
signal.Notify(signals, os.Interrupt, syscall.SIGTERM)

go configReloader(*mappingConfig, mapper, *cacheSize, logger, cacheOption)
go sighupConfigReloader(*mappingConfig, mapper, *cacheSize, logger, cacheOption)
go exporter.Listen(events)

<-signals
Expand Down