Add --web.disable-exporter-metrics flag

If this flag is set, the metrics about the exporter itself (go_*,
process_*, promhttp_*) will be excluded from /metrics.

The Kingpin way of handling boolean flags makes the negative flag
wording (_dis_able) the most reasonably one.

This also refactors the flow in node_exporter.go quite a bit to avoid
mixing up the global and a local registry and to avoid re-creating a
registry even if no filtering is requested.

Signed-off-by: beorn7 <beorn@soundcloud.com>
This commit is contained in:
beorn7 2018-11-08 16:26:21 +01:00
parent b1eec66640
commit cd2331a185
1 changed files with 97 additions and 46 deletions

View File

@ -27,51 +27,118 @@ import (
"gopkg.in/alecthomas/kingpin.v2"
)
func init() {
prometheus.MustRegister(version.NewCollector("node_exporter"))
// handler wraps an unfiltered http.Handler but uses a filtered handler,
// created on the fly, if filtering is requested. Create instances with
// newHandler.
type handler struct {
unfilteredHandler http.Handler
// exporterMetricsRegistry is a separate registry for the metrics about
// the exporter itself.
exporterMetricsRegistry *prometheus.Registry
includeExporterMetrics bool
}
func handler(w http.ResponseWriter, r *http.Request) {
func newHandler(includeExporterMetrics bool) *handler {
h := &handler{
exporterMetricsRegistry: prometheus.NewRegistry(),
includeExporterMetrics: includeExporterMetrics,
}
if h.includeExporterMetrics {
h.exporterMetricsRegistry.MustRegister(
prometheus.NewProcessCollector(prometheus.ProcessCollectorOpts{}),
prometheus.NewGoCollector(),
)
}
if innerHandler, err := h.innerHandler(); err != nil {
log.Fatalf("Couldn't create metrics handler: %s", err)
} else {
h.unfilteredHandler = innerHandler
}
return h
}
// ServeHTTP implements http.Handler.
func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
filters := r.URL.Query()["collect[]"]
log.Debugln("collect query:", filters)
if len(filters) == 0 {
// No filters, use the prepared unfiltered handler.
h.unfilteredHandler.ServeHTTP(w, r)
return
}
// To serve filtered metrics, we create a filtering handler on the fly.
filteredHandler, err := h.innerHandler(filters...)
if err != nil {
log.Warnln("Couldn't create filtered metrics handler:", err)
w.WriteHeader(http.StatusBadRequest)
w.Write([]byte(fmt.Sprintf("Couldn't create filtered metrics handler: %s", err)))
return
}
filteredHandler.ServeHTTP(w, r)
}
// innerHandler is used to create buth the one unfiltered http.Handler to be
// wrapped by the outer handler and also the filtered handlers created on the
// fly. The former is accomplished by calling innerHandler without any arguments
// (in which case it will log all the collectors enabled via command-line
// flags).
func (h *handler) innerHandler(filters ...string) (http.Handler, error) {
nc, err := collector.NewNodeCollector(filters...)
if err != nil {
log.Warnln("Couldn't create", err)
w.WriteHeader(http.StatusBadRequest)
w.Write([]byte(fmt.Sprintf("Couldn't create %s", err)))
return
return nil, fmt.Errorf("couldn't create collector: %s", err)
}
registry := prometheus.NewRegistry()
err = registry.Register(nc)
if err != nil {
log.Errorln("Couldn't register collector:", err)
w.WriteHeader(http.StatusInternalServerError)
w.Write([]byte(fmt.Sprintf("Couldn't register collector: %s", err)))
return
// Only log the creation of an unfiltered handler, which should happen
// only once upon startup.
if len(filters) == 0 {
log.Infof("Enabled collectors:")
collectors := []string{}
for n := range nc.Collectors {
collectors = append(collectors, n)
}
sort.Strings(collectors)
for _, n := range collectors {
log.Infof(" - %s", n)
}
}
gatherers := prometheus.Gatherers{
prometheus.DefaultGatherer,
registry,
r := prometheus.NewRegistry()
r.MustRegister(version.NewCollector("node_exporter"))
if err := r.Register(nc); err != nil {
return nil, fmt.Errorf("couldn't register node collector: %s", err)
}
// Delegate http serving to Prometheus client library, which will call collector.Collect.
h := promhttp.InstrumentMetricHandler(
registry,
promhttp.HandlerFor(gatherers,
promhttp.HandlerOpts{
ErrorLog: log.NewErrorLogger(),
ErrorHandling: promhttp.ContinueOnError,
}),
handler := promhttp.HandlerFor(
prometheus.Gatherers{h.exporterMetricsRegistry, r},
promhttp.HandlerOpts{
ErrorLog: log.NewErrorLogger(),
ErrorHandling: promhttp.ContinueOnError,
},
)
h.ServeHTTP(w, r)
if h.includeExporterMetrics {
// Note that we have to use h.exporterMetricsRegistry here to
// use the same promhttp metrics for all expositions.
handler = promhttp.InstrumentMetricHandler(
h.exporterMetricsRegistry, handler,
)
}
return handler, nil
}
func main() {
var (
listenAddress = kingpin.Flag("web.listen-address", "Address on which to expose metrics and web interface.").Default(":9100").String()
metricsPath = kingpin.Flag("web.telemetry-path", "Path under which to expose metrics.").Default("/metrics").String()
listenAddress = kingpin.Flag(
"web.listen-address",
"Address on which to expose metrics and web interface.",
).Default(":9100").String()
metricsPath = kingpin.Flag(
"web.telemetry-path",
"Path under which to expose metrics.",
).Default("/metrics").String()
disableExporterMetrics = kingpin.Flag(
"web.disable-exporter-metrics",
"Exclude metrics about the exporter itself (promhttp_*, process_*, go_*).",
).Bool()
)
log.AddFlags(kingpin.CommandLine)
@ -82,22 +149,7 @@ func main() {
log.Infoln("Starting node_exporter", version.Info())
log.Infoln("Build context", version.BuildContext())
// This instance is only used to check collector creation and logging.
nc, err := collector.NewNodeCollector()
if err != nil {
log.Fatalf("Couldn't create collector: %s", err)
}
log.Infof("Enabled collectors:")
collectors := []string{}
for n := range nc.Collectors {
collectors = append(collectors, n)
}
sort.Strings(collectors)
for _, n := range collectors {
log.Infof(" - %s", n)
}
http.HandleFunc(*metricsPath, handler)
http.Handle(*metricsPath, newHandler(!*disableExporterMetrics))
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte(`<html>
<head><title>Node Exporter</title></head>
@ -109,8 +161,7 @@ func main() {
})
log.Infoln("Listening on", *listenAddress)
err = http.ListenAndServe(*listenAddress, nil)
if err != nil {
if err := http.ListenAndServe(*listenAddress, nil); err != nil {
log.Fatal(err)
}
}