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main.go
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main.go
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// Copyright 2018 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"
"os"
"os/signal"
"strings"
"sync"
"syscall"
"github.com/alecthomas/kingpin/v2"
"github.com/go-kit/log"
"github.com/go-kit/log/level"
"github.com/prometheus/client_golang/prometheus"
versioncollector "github.com/prometheus/client_golang/prometheus/collectors/version"
"github.com/prometheus/client_golang/prometheus/promauto"
"github.com/prometheus/client_golang/prometheus/promhttp"
"github.com/prometheus/common/promlog"
"github.com/prometheus/common/promlog/flag"
"github.com/prometheus/common/version"
"github.com/prometheus/exporter-toolkit/web"
webflag "github.com/prometheus/exporter-toolkit/web/kingpinflag"
yaml "gopkg.in/yaml.v2"
"github.com/prometheus/snmp_exporter/collector"
"github.com/prometheus/snmp_exporter/config"
)
const (
namespace = "snmp"
)
var (
configFile = kingpin.Flag("config.file", "Path to configuration file.").Default("snmp.yml").Strings()
dryRun = kingpin.Flag("dry-run", "Only verify configuration is valid and exit.").Default("false").Bool()
concurrency = kingpin.Flag("snmp.module-concurrency", "The number of modules to fetch concurrently per scrape").Default("1").Int()
debugSNMP = kingpin.Flag("snmp.debug-packets", "Include a full debug trace of SNMP packet traffics.").Default("false").Bool()
expandEnvVars = kingpin.Flag("config.expand-environment-variables", "Expand environment variables to source secrets").Default("false").Bool()
metricsPath = kingpin.Flag(
"web.telemetry-path",
"Path under which to expose metrics.",
).Default("/metrics").String()
toolkitFlags = webflag.AddFlags(kingpin.CommandLine, ":9116")
// Metrics about the SNMP exporter itself.
snmpRequestErrors = promauto.NewCounter(
prometheus.CounterOpts{
Namespace: namespace,
Name: "request_errors_total",
Help: "Errors in requests to the SNMP exporter",
},
)
snmpCollectionDuration = promauto.NewHistogramVec(
prometheus.HistogramOpts{
Namespace: namespace,
Name: "collection_duration_seconds",
Help: "Duration of collections by the SNMP exporter",
},
[]string{"module"},
)
sc = &SafeConfig{
C: &config.Config{},
}
reloadCh chan chan error
)
const (
proberPath = "/snmp"
configPath = "/config"
)
func handler(w http.ResponseWriter, r *http.Request, logger log.Logger, exporterMetrics collector.Metrics) {
query := r.URL.Query()
debug := *debugSNMP
if query.Get("snmp_debug_packets") == "true" {
debug = true
// TODO: This doesn't work the way I want.
// logger = level.NewFilter(logger, level.AllowDebug())
level.Debug(logger).Log("msg", "Debug query param enabled")
}
target := query.Get("target")
if len(query["target"]) != 1 || target == "" {
http.Error(w, "'target' parameter must be specified once", http.StatusBadRequest)
snmpRequestErrors.Inc()
return
}
authName := query.Get("auth")
if len(query["auth"]) > 1 {
http.Error(w, "'auth' parameter must only be specified once", http.StatusBadRequest)
snmpRequestErrors.Inc()
return
}
if authName == "" {
authName = "public_v2"
}
snmpContext := query.Get("snmp_context")
if len(query["snmp_context"]) > 1 {
http.Error(w, "'snmp_context' parameter must only be specified once", http.StatusBadRequest)
snmpRequestErrors.Inc()
return
}
queryModule := query["module"]
if len(queryModule) == 0 {
queryModule = append(queryModule, "if_mib")
}
uniqueM := make(map[string]bool)
var modules []string
for _, qm := range queryModule {
for _, m := range strings.Split(qm, ",") {
if m == "" {
continue
}
if _, ok := uniqueM[m]; !ok {
uniqueM[m] = true
modules = append(modules, m)
}
}
}
sc.RLock()
auth, authOk := sc.C.Auths[authName]
if !authOk {
sc.RUnlock()
http.Error(w, fmt.Sprintf("Unknown auth '%s'", authName), http.StatusBadRequest)
snmpRequestErrors.Inc()
return
}
var nmodules []*collector.NamedModule
for _, m := range modules {
module, moduleOk := sc.C.Modules[m]
if !moduleOk {
sc.RUnlock()
http.Error(w, fmt.Sprintf("Unknown module '%s'", m), http.StatusBadRequest)
snmpRequestErrors.Inc()
return
}
nmodules = append(nmodules, collector.NewNamedModule(m, module))
}
sc.RUnlock()
logger = log.With(logger, "auth", authName, "target", target)
registry := prometheus.NewRegistry()
c := collector.New(r.Context(), target, authName, snmpContext, auth, nmodules, logger, exporterMetrics, *concurrency, debug)
registry.MustRegister(c)
// Delegate http serving to Prometheus client library, which will call collector.Collect.
h := promhttp.HandlerFor(registry, promhttp.HandlerOpts{})
h.ServeHTTP(w, r)
}
func updateConfiguration(w http.ResponseWriter, r *http.Request) {
switch r.Method {
case "POST":
rc := make(chan error)
reloadCh <- rc
if err := <-rc; err != nil {
http.Error(w, fmt.Sprintf("failed to reload config: %s", err), http.StatusInternalServerError)
}
default:
http.Error(w, "POST method expected", http.StatusBadRequest)
}
}
type SafeConfig struct {
sync.RWMutex
C *config.Config
}
func (sc *SafeConfig) ReloadConfig(configFile []string, expandEnvVars bool) (err error) {
conf, err := config.LoadFile(configFile, expandEnvVars)
if err != nil {
return err
}
sc.Lock()
sc.C = conf
// Initialize metrics.
for module := range sc.C.Modules {
snmpCollectionDuration.WithLabelValues(module)
}
sc.Unlock()
return nil
}
func main() {
promlogConfig := &promlog.Config{}
flag.AddFlags(kingpin.CommandLine, promlogConfig)
kingpin.Version(version.Print("snmp_exporter"))
kingpin.HelpFlag.Short('h')
kingpin.Parse()
logger := promlog.New(promlogConfig)
if *concurrency < 1 {
*concurrency = 1
}
level.Info(logger).Log("msg", "Starting snmp_exporter", "version", version.Info(), "concurrency", concurrency, "debug_snmp", debugSNMP)
level.Info(logger).Log("build_context", version.BuildContext())
prometheus.MustRegister(versioncollector.NewCollector("snmp_exporter"))
// Bail early if the config is bad.
err := sc.ReloadConfig(*configFile, *expandEnvVars)
if err != nil {
level.Error(logger).Log("msg", "Error parsing config file", "err", err)
level.Error(logger).Log("msg", "Possible old config file, see https://github.com/prometheus/snmp_exporter/blob/main/auth-split-migration.md")
os.Exit(1)
}
// Exit if in dry-run mode.
if *dryRun {
level.Info(logger).Log("msg", "Configuration parsed successfully")
return
}
hup := make(chan os.Signal, 1)
reloadCh = make(chan chan error)
signal.Notify(hup, syscall.SIGHUP)
go func() {
for {
select {
case <-hup:
if err := sc.ReloadConfig(*configFile, *expandEnvVars); err != nil {
level.Error(logger).Log("msg", "Error reloading config", "err", err)
} else {
level.Info(logger).Log("msg", "Loaded config file")
}
case rc := <-reloadCh:
if err := sc.ReloadConfig(*configFile, *expandEnvVars); err != nil {
level.Error(logger).Log("msg", "Error reloading config", "err", err)
rc <- err
} else {
level.Info(logger).Log("msg", "Loaded config file")
rc <- nil
}
}
}
}()
buckets := prometheus.ExponentialBuckets(0.0001, 2, 15)
exporterMetrics := collector.Metrics{
SNMPCollectionDuration: snmpCollectionDuration,
SNMPUnexpectedPduType: promauto.NewCounter(
prometheus.CounterOpts{
Namespace: namespace,
Name: "unexpected_pdu_type_total",
Help: "Unexpected Go types in a PDU.",
},
),
SNMPDuration: promauto.NewHistogram(
prometheus.HistogramOpts{
Namespace: namespace,
Name: "packet_duration_seconds",
Help: "A histogram of latencies for SNMP packets.",
Buckets: buckets,
},
),
SNMPPackets: promauto.NewCounter(
prometheus.CounterOpts{
Namespace: namespace,
Name: "packets_total",
Help: "Number of SNMP packet sent, including retries.",
},
),
SNMPRetries: promauto.NewCounter(
prometheus.CounterOpts{
Namespace: namespace,
Name: "packet_retries_total",
Help: "Number of SNMP packet retries.",
},
),
SNMPInflight: promauto.NewGauge(
prometheus.GaugeOpts{
Namespace: namespace,
Name: "request_in_flight",
Help: "Current number of SNMP scrapes being requested.",
},
),
}
http.Handle(*metricsPath, promhttp.Handler()) // Normal metrics endpoint for SNMP exporter itself.
// Endpoint to do SNMP scrapes.
http.HandleFunc(proberPath, func(w http.ResponseWriter, r *http.Request) {
handler(w, r, logger, exporterMetrics)
})
http.HandleFunc("/-/reload", updateConfiguration) // Endpoint to reload configuration.
if *metricsPath != "/" && *metricsPath != "" {
landingConfig := web.LandingConfig{
Name: "SNMP Exporter",
Description: "Prometheus Exporter for SNMP targets",
Version: version.Info(),
Form: web.LandingForm{
Action: proberPath,
Inputs: []web.LandingFormInput{
{
Label: "Target",
Type: "text",
Name: "target",
Placeholder: "X.X.X.X/[::X]",
Value: "::1",
},
{
Label: "Auth",
Type: "text",
Name: "auth",
Placeholder: "auth",
Value: "public_v2",
},
{
Label: "Module",
Type: "text",
Name: "module",
Placeholder: "module",
Value: "if_mib",
},
},
},
Links: []web.LandingLinks{
{
Address: configPath,
Text: "Config",
},
{
Address: *metricsPath,
Text: "Metrics",
},
},
}
landingPage, err := web.NewLandingPage(landingConfig)
if err != nil {
level.Error(logger).Log("err", err)
os.Exit(1)
}
http.Handle("/", landingPage)
}
http.HandleFunc(configPath, func(w http.ResponseWriter, r *http.Request) {
sc.RLock()
c, err := yaml.Marshal(sc.C)
sc.RUnlock()
if err != nil {
level.Error(logger).Log("msg", "Error marshaling configuration", "err", err)
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
w.Write(c)
})
srv := &http.Server{}
if err := web.ListenAndServe(srv, toolkitFlags, logger); err != nil {
level.Error(logger).Log("msg", "Error starting HTTP server", "err", err)
os.Exit(1)
}
}