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// Copyright 2015 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
import (
"fmt"
"net/http"
_ "net/http/pprof"
"sort"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
"github.com/prometheus/common/log"
"github.com/prometheus/common/version"
"github.com/prometheus/node_exporter/collector"
"gopkg.in/alecthomas/kingpin.v2"
)
// 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
maxRequests int
}
func newHandler(includeExporterMetrics bool, maxRequests int) *handler {
h := &handler{
exporterMetricsRegistry: prometheus.NewRegistry(),
includeExporterMetrics: includeExporterMetrics,
maxRequests: maxRequests,
}
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 {
return nil, fmt.Errorf("couldn't create collector: %s", err)
}
// 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)
}
}
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)
}
handler := promhttp.HandlerFor(
prometheus.Gatherers{h.exporterMetricsRegistry, r},
promhttp.HandlerOpts{
ErrorLog: log.NewErrorLogger(),
ErrorHandling: promhttp.ContinueOnError,
MaxRequestsInFlight: h.maxRequests,
},
)
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()
disableExporterMetrics = kingpin.Flag(
"web.disable-exporter-metrics",
"Exclude metrics about the exporter itself (promhttp_*, process_*, go_*).",
).Bool()
maxRequests = kingpin.Flag(
"web.max-requests",
"Maximum number of parallel scrape requests. Use 0 to disable.",
).Default("40").Int()
)
log.AddFlags(kingpin.CommandLine)
kingpin.Version(version.Print("node_exporter"))
kingpin.HelpFlag.Short('h')
kingpin.Parse()
log.Infoln("Starting node_exporter", version.Info())
log.Infoln("Build context", version.BuildContext())
http.Handle(*metricsPath, newHandler(!*disableExporterMetrics, *maxRequests))
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte(`<html>
<head><title>Node Exporter</title></head>
<body>
<h1>Node Exporter</h1>
<p><a href="` + *metricsPath + `">Metrics</a></p>
</body>
</html>`))
})
log.Infoln("Listening on", *listenAddress)
if err := http.ListenAndServe(*listenAddress, nil); err != nil {
log.Fatal(err)
}
}
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