offloaded most of the route processing to exporter-toolkit

Signed-off-by: kwilt <[email protected]>

Author: kwilt

go.mod

@@ -4,6 +4,8 @@ go 1.22
 
 toolchain go1.23.1
 
+replace github.com/prometheus/exporter-toolkit => /home/knapdev/exporter-toolkit
+
 require (
 	github.com/alecthomas/kingpin/v2 v2.4.0
 	github.com/gosnmp/gosnmp v1.38.0

go.sum

@@ -44,8 +44,6 @@ github.com/prometheus/client_model v0.6.1 h1:ZKSh/rekM+n3CeS952MLRAdFwIKqeY8b62p
 github.com/prometheus/client_model v0.6.1/go.mod h1:OrxVMOVHjw3lKMa8+x6HeMGkHMQyHDk9E3jmP2AmGiY=
 github.com/prometheus/common v0.62.0 h1:xasJaQlnWAeyHdUBeGjXmutelfJHWMRr+Fg4QszZ2Io=
 github.com/prometheus/common v0.62.0/go.mod h1:vyBcEuLSvWos9B1+CyL7JZ2up+uFzXhkqml0W5zIY1I=
-github.com/prometheus/exporter-toolkit v0.14.0 h1:NMlswfibpcZZ+H0sZBiTjrA3/aBFHkNZqE+iCj5EmRg=
-github.com/prometheus/exporter-toolkit v0.14.0/go.mod h1:Gu5LnVvt7Nr/oqTBUC23WILZepW0nffNo10XdhQcwWA=
 github.com/prometheus/procfs v0.15.1 h1:YagwOFzUgYfKKHX6Dr+sHT7km/hxC76UB0learggepc=
 github.com/prometheus/procfs v0.15.1/go.mod h1:fB45yRUv8NstnjriLhBQLuOUt+WW4BsoGhij/e3PBqk=
 github.com/rogpeppe/go-internal v1.10.0 h1:TMyTOH3F/DB16zRVcYyreMH6GnZZrwQVAoYjRBZyWFQ=

main.go

@@ -14,13 +14,9 @@
 package main
 
 import (
-	"errors"
 	"fmt"
 	"log/slog"
-	"net"
 	"net/http"
-	"net/http/pprof"
-	"net/url"
 	"os"
 	"os/signal"
 	"path"
@@ -235,37 +231,6 @@ func main() {
 		return
 	}
 
-	// Infer or set snmp exporter externalURL
-	listenAddrs := toolkitFlags.WebListenAddresses
-	if *externalURL == "" && *toolkitFlags.WebSystemdSocket {
-		logger.Error("Cannot automatically infer external URL with systemd socket listener. Please provide --web.external-url")
-		os.Exit(1)
-	} else if *externalURL == "" && len(*listenAddrs) > 1 {
-		logger.Info("Inferring external URL from first provided listen address")
-	}
-
-	beURL, err := computeExternalURL(*externalURL, (*listenAddrs)[0])
-	if err != nil {
-		logger.Error("Failed to determine external URL", "err", err)
-		os.Exit(1)
-	}
-	logger.Debug("External URL", "url", beURL.String())
-
-	// Default -web.route-prefix to path of -web.external-url
-	if *routePrefix == "" {
-		*routePrefix = beURL.Path
-	}
-
-	// routePrefix must always be at least '/'
-	*routePrefix = "/" + strings.Trim(*routePrefix, "/")
-	logger.Debug("Route prefix", "prefix", *routePrefix)
-	// routePrefix requires path to have trailing "/" in order
-	// for browsers to interpret the path-relative path correctly, instead of stripping it.
-	if *routePrefix != "/" {
-		*routePrefix = *routePrefix + "/"
-	}
-	logger.Debug(*routePrefix)
-
 	hup := make(chan os.Signal, 1)
 	reloadCh = make(chan chan error)
 	signal.Notify(hup, syscall.SIGHUP)
@@ -331,35 +296,16 @@ func main() {
 		),
 	}
 
-	// Match Prometheus behavior and redirect over externalURL for root path only
-	// if routePrefix is different from "/"
-	if *routePrefix != "/" {
-		http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
-			if r.URL.Path != "/" {
-				http.NotFound(w, r)
-				return
-			}
-			http.Redirect(w, r, beURL.String(), http.StatusFound)
-		})
-	}
-
-	http.Handle(path.Join(*routePrefix, *metricsPath), promhttp.Handler()) // Normal metrics endpoint for SNMP exporter itself.
-	// Endpoint to do SNMP scrapes.
-	http.HandleFunc(path.Join(*routePrefix, proberPath), func(w http.ResponseWriter, r *http.Request) {
-		handler(w, r, logger, exporterMetrics)
-	})
-	http.HandleFunc(path.Join(*routePrefix, "/-/reload"), updateConfiguration) // Endpoint to reload configuration.
-	// Serve pprof under the route prefix. These links are displayed on the landing page.
-	http.HandleFunc(path.Join(*routePrefix, "debug/pprof/"), pprof.Index)
-	http.HandleFunc(path.Join(*routePrefix, "debug/pprof/profile"), pprof.Profile)
-	http.HandleFunc(path.Join(*routePrefix, "debug/pprof/heap"), pprof.Handler("heap").ServeHTTP)
-
 	if *metricsPath != "/" && *metricsPath != "" {
 		landingConfig := web.LandingConfig{
-			Name:        "SNMP Exporter",
-			Description: "Prometheus Exporter for SNMP targets",
-			Version:     version.Info(),
-			RoutePrefix: *routePrefix,
+			Name:             "SNMP Exporter",
+			Description:      "Prometheus Exporter for SNMP targets",
+			Version:          version.Info(),
+			RoutePrefix:      *routePrefix,
+			ExternalURL:      *externalURL,
+			ListenAddresses:  *toolkitFlags.WebListenAddresses,
+			UseSystemdSocket: *toolkitFlags.WebSystemdSocket,
+			Logger:           logger,
 			Form: web.LandingForm{
 				Action: proberPath,
 				Inputs: []web.LandingFormInput{
@@ -397,14 +343,24 @@ func main() {
 				},
 			},
 		}
-		landingPage, err := web.NewLandingPage(landingConfig)
+		landingPage, processedRoutePrefix, err := web.NewLandingPage(landingConfig)
 		if err != nil {
 			logger.Error("Error creating landing page", "err", err)
 			os.Exit(1)
 		}
+		*routePrefix = processedRoutePrefix
 		http.Handle(*routePrefix, landingPage)
 	}
 
+	http.Handle(path.Join(*routePrefix, *metricsPath), promhttp.Handler()) // Normal metrics endpoint for SNMP exporter itself.
+
+	// Endpoint to do SNMP scrapes.
+	http.HandleFunc(path.Join(*routePrefix, proberPath), func(w http.ResponseWriter, r *http.Request) {
+		handler(w, r, logger, exporterMetrics)
+	})
+
+	http.HandleFunc(path.Join(*routePrefix, "/-/reload"), updateConfiguration) // Endpoint to reload configuration.
+
 	http.HandleFunc(path.Join(*routePrefix, configPath), func(w http.ResponseWriter, r *http.Request) {
 		sc.RLock()
 		c, err := yaml.Marshal(sc.C)
@@ -423,41 +379,3 @@ func main() {
 		os.Exit(1)
 	}
 }
-
-func startsOrEndsWithQuote(s string) bool {
-	return strings.HasPrefix(s, "\"") || strings.HasPrefix(s, "'") ||
-		strings.HasSuffix(s, "\"") || strings.HasSuffix(s, "'")
-}
-
-// computeExternalURL computes a sanitized external URL from a raw input. It infers unset
-// URL parts from the OS and the given listen address.
-func computeExternalURL(u, listenAddr string) (*url.URL, error) {
-	if u == "" {
-		hostname, err := os.Hostname()
-		if err != nil {
-			return nil, err
-		}
-		_, port, err := net.SplitHostPort(listenAddr)
-		if err != nil {
-			return nil, err
-		}
-		u = fmt.Sprintf("http://%s:%s/", hostname, port)
-	}
-
-	if startsOrEndsWithQuote(u) {
-		return nil, errors.New("URL must not begin or end with quotes")
-	}
-
-	eu, err := url.Parse(u)
-	if err != nil {
-		return nil, err
-	}
-
-	ppref := strings.TrimRight(eu.Path, "/")
-	if ppref != "" && !strings.HasPrefix(ppref, "/") {
-		ppref = "/" + ppref
-	}
-	eu.Path = ppref
-
-	return eu, nil
-}