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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"
"log/slog"
"net/http"
_ "net/http/pprof"
"os"
"os/user"
"runtime"
"slices"
"sort"
"github.com/prometheus/common/promslog"
"github.com/prometheus/common/promslog/flag"
"github.com/prometheus/client_golang/prometheus"
promcollectors "github.com/prometheus/client_golang/prometheus/collectors"
versioncollector "github.com/prometheus/client_golang/prometheus/collectors/version"
"github.com/prometheus/client_golang/prometheus/promhttp"
"github.com/prometheus/common/version"
"github.com/prometheus/exporter-toolkit/web"
"github.com/prometheus/exporter-toolkit/web/kingpinflag"
"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
// enabledCollectors list is used for logging and filtering
enabledCollectors []string
// exporterMetricsRegistry is a separate registry for the metrics about
// the exporter itself.
exporterMetricsRegistry *prometheus.Registry
includeExporterMetrics bool
maxRequests int
logger *slog.Logger
}
func newHandler(includeExporterMetrics bool, maxRequests int, logger *slog.Logger) *handler {
h := &handler{
exporterMetricsRegistry: prometheus.NewRegistry(),
includeExporterMetrics: includeExporterMetrics,
maxRequests: maxRequests,
logger: logger,
}
if h.includeExporterMetrics {
h.exporterMetricsRegistry.MustRegister(
promcollectors.NewProcessCollector(promcollectors.ProcessCollectorOpts{}),
promcollectors.NewGoCollector(),
)
}
if innerHandler, err := h.innerHandler(); err != nil {
panic(fmt.Sprintf("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) {
collects := r.URL.Query()["collect[]"]
h.logger.Debug("collect query:", "collects", collects)
excludes := r.URL.Query()["exclude[]"]
h.logger.Debug("exclude query:", "excludes", excludes)
if len(collects) == 0 && len(excludes) == 0 {
// No filters, use the prepared unfiltered handler.
h.unfilteredHandler.ServeHTTP(w, r)
return
}
if len(collects) > 0 && len(excludes) > 0 {
h.logger.Debug("rejecting combined collect and exclude queries")
w.WriteHeader(http.StatusBadRequest)
w.Write([]byte("Combined collect and exclude queries are not allowed."))
return
}
filters := &collects
if len(excludes) > 0 {
// In exclude mode, filtered collectors = enabled - excludeed.
f := []string{}
for _, c := range h.enabledCollectors {
if (slices.Index(excludes, c)) == -1 {
f = append(f, c)
}
}
filters = &f
}
// To serve filtered metrics, we create a filtering handler on the fly.
filteredHandler, err := h.innerHandler(*filters...)
if err != nil {
h.logger.Warn("Couldn't create filtered metrics handler:", "err", 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 both 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(h.logger, 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 {
h.logger.Info("Enabled collectors")
for n := range nc.Collectors {
h.enabledCollectors = append(h.enabledCollectors, n)
}
sort.Strings(h.enabledCollectors)
for _, c := range h.enabledCollectors {
h.logger.Info(c)
}
}
r := prometheus.NewRegistry()
r.MustRegister(versioncollector.NewCollector("node_exporter"))
if err := r.Register(nc); err != nil {
return nil, fmt.Errorf("couldn't register node collector: %s", err)
}
var handler http.Handler
if h.includeExporterMetrics {
handler = promhttp.HandlerFor(
prometheus.Gatherers{h.exporterMetricsRegistry, r},
promhttp.HandlerOpts{
ErrorLog: slog.NewLogLogger(h.logger.Handler(), slog.LevelError),
ErrorHandling: promhttp.ContinueOnError,
MaxRequestsInFlight: h.maxRequests,
Registry: h.exporterMetricsRegistry,
},
)
// Note that we have to use h.exporterMetricsRegistry here to
// use the same promhttp metrics for all expositions.
handler = promhttp.InstrumentMetricHandler(
h.exporterMetricsRegistry, handler,
)
} else {
handler = promhttp.HandlerFor(
r,
promhttp.HandlerOpts{
ErrorLog: slog.NewLogLogger(h.logger.Handler(), slog.LevelError),
ErrorHandling: promhttp.ContinueOnError,
MaxRequestsInFlight: h.maxRequests,
},
)
}
return handler, nil
}
func main() {
var (
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()
disableDefaultCollectors = kingpin.Flag(
"collector.disable-defaults",
"Set all collectors to disabled by default.",
).Default("false").Bool()
maxProcs = kingpin.Flag(
"runtime.gomaxprocs", "The target number of CPUs Go will run on (GOMAXPROCS)",
).Envar("GOMAXPROCS").Default("1").Int()
toolkitFlags = kingpinflag.AddFlags(kingpin.CommandLine, ":9100")
)
promslogConfig := &promslog.Config{}
flag.AddFlags(kingpin.CommandLine, promslogConfig)
kingpin.Version(version.Print("node_exporter"))
kingpin.CommandLine.UsageWriter(os.Stdout)
kingpin.HelpFlag.Short('h')
kingpin.Parse()
logger := promslog.New(promslogConfig)
if *disableDefaultCollectors {
collector.DisableDefaultCollectors()
}
logger.Info("Starting node_exporter", "version", version.Info())
logger.Info("Build context", "build_context", version.BuildContext())
if user, err := user.Current(); err == nil && user.Uid == "0" {
logger.Warn("Node Exporter is running as root user. This exporter is designed to run as unprivileged user, root is not required.")
}
runtime.GOMAXPROCS(*maxProcs)
logger.Debug("Go MAXPROCS", "procs", runtime.GOMAXPROCS(0))
http.Handle(*metricsPath, newHandler(!*disableExporterMetrics, *maxRequests, logger))
if *metricsPath != "/" {
landingConfig := web.LandingConfig{
Name: "Node Exporter",
Description: "Prometheus Node Exporter",
Version: version.Info(),
Links: []web.LandingLinks{
{
Address: *metricsPath,
Text: "Metrics",
},
},
}
landingPage, err := web.NewLandingPage(landingConfig)
if err != nil {
logger.Error(err.Error())
os.Exit(1)
}
http.Handle("/", landingPage)
}
server := &http.Server{}
if err := web.ListenAndServe(server, toolkitFlags, logger); err != nil {
logger.Error(err.Error())
os.Exit(1)
}
}
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