feat: add --web.nginx-metrics-only flag

README.md

@@ -169,6 +169,8 @@ Flags:
       --web.listen-address=:9113 ...
                                  Addresses on which to expose metrics and web interface. Repeatable for multiple addresses. ($LISTEN_ADDRESS)
       --web.config.file=""       Path to configuration file that can enable TLS or authentication. See: https://github.com/prometheus/exporter-toolkit/blob/master/docs/web-configuration.md ($CONFIG_FILE)
+      --[no-]web.nginx-metrics-only
+                                 Expose only NGINX metrics (no Go runtime, build info, or promhttp metrics). ($NGINX_METRICS_ONLY)
       --web.telemetry-path="/metrics"
                                  Path under which to expose metrics. ($TELEMETRY_PATH)
       --[no-]nginx.plus          Start the exporter for NGINX Plus. By default, the exporter is started for NGINX. ($NGINX_PLUS)
@@ -198,7 +200,9 @@ Flags:
 | `nginx_exporter_build_info`                  | Gauge    | Shows the exporter build information.        | `branch`, `goarch`, `goos`, `goversion`, `revision`, `tags` and `version` |
 | `promhttp_metric_handler_requests_total`     | Counter  | Total number of scrapes by HTTP status code. | `code` (the HTTP status code)                                             |
 | `promhttp_metric_handler_requests_in_flight` | Gauge    | Current number of scrapes being served.      | []                                                                        |
-| `go_*`                                       | Multiple | Go runtime metrics.                          | []                                                                        |
+| `go_*`                                       | Multiple | Go runtime metrics (disabled with `--web.nginx-metrics-only`). | []                                                                        |
+
+When `--web.nginx-metrics-only` is set, only NGINX metrics are exposed (no Go runtime, build info, or promhttp metrics).
 
 ### Metrics for NGINX OSS
 

exporter.go

@@ -84,22 +84,29 @@ var (
 	constLabels = map[string]string{}
 
 	// Command-line flags.
-	webConfig     = kingpinflag.AddFlags(kingpin.CommandLine, ":9113")
-	metricsPath   = kingpin.Flag("web.telemetry-path", "Path under which to expose metrics.").Default("/metrics").Envar("TELEMETRY_PATH").String()
-	nginxPlus     = kingpin.Flag("nginx.plus", "Start the exporter for NGINX Plus. By default, the exporter is started for NGINX.").Default("false").Envar("NGINX_PLUS").Bool()
-	scrapeURIs    = kingpin.Flag("nginx.scrape-uri", "A URI or unix domain socket path for scraping NGINX or NGINX Plus metrics. For NGINX, the stub_status page must be available through the URI. For NGINX Plus -- the API. Repeatable for multiple URIs.").Default("http://127.0.0.1:8080/stub_status").Envar("SCRAPE_URI").HintOptions("http://127.0.0.1:8080/stub_status", "http://127.0.0.1:8080/api").Strings()
-	sslVerify     = kingpin.Flag("nginx.ssl-verify", "Perform SSL certificate verification.").Default("false").Envar("SSL_VERIFY").Bool()
-	sslCaCert     = kingpin.Flag("nginx.ssl-ca-cert", "Path to the PEM encoded CA certificate file used to validate the servers SSL certificate.").Default("").Envar("SSL_CA_CERT").String()
-	sslClientCert = kingpin.Flag("nginx.ssl-client-cert", "Path to the PEM encoded client certificate file to use when connecting to the server.").Default("").Envar("SSL_CLIENT_CERT").String()
-	sslClientKey  = kingpin.Flag("nginx.ssl-client-key", "Path to the PEM encoded client certificate key file to use when connecting to the server.").Default("").Envar("SSL_CLIENT_KEY").String()
-	useProxyProto = kingpin.Flag("nginx.proxy-protocol", "Pass proxy protocol payload to nginx listeners.").Default("false").Envar("PROXY_PROTOCOL").Bool()
+	webConfig        = kingpinflag.AddFlags(kingpin.CommandLine, ":9113")
+	metricsPath      = kingpin.Flag("web.telemetry-path", "Path under which to expose metrics.").Default("/metrics").Envar("TELEMETRY_PATH").String()
+	nginxMetricsOnly = kingpin.Flag("web.nginx-metrics-only", "Expose only NGINX metrics (no Go runtime, build info, or promhttp metrics).").Default("false").Envar("NGINX_METRICS_ONLY").Bool()
+	nginxPlus        = kingpin.Flag("nginx.plus", "Start the exporter for NGINX Plus. By default, the exporter is started for NGINX.").Default("false").Envar("NGINX_PLUS").Bool()
+	scrapeURIs       = kingpin.Flag("nginx.scrape-uri", "A URI or unix domain socket path for scraping NGINX or NGINX Plus metrics. For NGINX, the stub_status page must be available through the URI. For NGINX Plus -- the API. Repeatable for multiple URIs.").Default("http://127.0.0.1:8080/stub_status").Envar("SCRAPE_URI").HintOptions("http://127.0.0.1:8080/stub_status", "http://127.0.0.1:8080/api").Strings()
+	sslVerify        = kingpin.Flag("nginx.ssl-verify", "Perform SSL certificate verification.").Default("false").Envar("SSL_VERIFY").Bool()
+	sslCaCert        = kingpin.Flag("nginx.ssl-ca-cert", "Path to the PEM encoded CA certificate file used to validate the servers SSL certificate.").Default("").Envar("SSL_CA_CERT").String()
+	sslClientCert    = kingpin.Flag("nginx.ssl-client-cert", "Path to the PEM encoded client certificate file to use when connecting to the server.").Default("").Envar("SSL_CLIENT_CERT").String()
+	sslClientKey     = kingpin.Flag("nginx.ssl-client-key", "Path to the PEM encoded client certificate key file to use when connecting to the server.").Default("").Envar("SSL_CLIENT_KEY").String()
+	useProxyProto    = kingpin.Flag("nginx.proxy-protocol", "Pass proxy protocol payload to nginx listeners.").Default("false").Envar("PROXY_PROTOCOL").Bool()
 
 	// Custom command-line flags.
 	timeout = createPositiveDurationFlag(kingpin.Flag("nginx.timeout", "A timeout for scraping metrics from NGINX or NGINX Plus.").Default("5s").Envar("TIMEOUT").HintOptions("5s", "10s", "30s", "1m", "5m"))
 )
 
 const exporterName = "nginx_exporter"
 
+func mustRegister(registerer prometheus.Registerer, c prometheus.Collector) {
+	if err := registerer.Register(c); err != nil {
+		panic(err)
+	}
+}
+
 func main() {
 	kingpin.Flag("prometheus.const-label", "Label that will be used in every metric. Format is label=value. It can be repeated multiple times.").Envar("CONST_LABELS").StringMapVar(&constLabels)
 
@@ -126,7 +133,15 @@ func main() {
 	logger.Info("nginx-prometheus-exporter", "version", common_version.Info())
 	logger.Info("build context", "build_context", common_version.BuildContext())
 
-	prometheus.MustRegister(version.NewCollector(exporterName))
+	registerer := prometheus.DefaultRegisterer
+	gatherer := prometheus.DefaultGatherer
+	if *nginxMetricsOnly {
+		registry := prometheus.NewRegistry()
+		registerer = registry
+		gatherer = registry
+	} else {
+		mustRegister(registerer, version.NewCollector(exporterName))
+	}
 
 	if len(*scrapeURIs) == 0 {
 		logger.Error("no scrape addresses provided")
@@ -164,18 +179,22 @@ func main() {
 	}
 
 	if len(*scrapeURIs) == 1 {
-		registerCollector(logger, transport, (*scrapeURIs)[0], constLabels)
+		registerCollector(registerer, logger, transport, (*scrapeURIs)[0], constLabels)
 	} else {
 		for _, addr := range *scrapeURIs {
 			// add scrape URI to const labels
 			labels := maps.Clone(constLabels)
 			labels["addr"] = addr
 
-			registerCollector(logger, transport, addr, labels)
+			registerCollector(registerer, logger, transport, addr, labels)
 		}
 	}
 
-	http.Handle(*metricsPath, promhttp.Handler())
+	if *nginxMetricsOnly {
+		http.Handle(*metricsPath, promhttp.HandlerFor(gatherer, promhttp.HandlerOpts{}))
+	} else {
+		http.Handle(*metricsPath, promhttp.Handler())
+	}
 
 	if *metricsPath != "/" && *metricsPath != "" {
 		landingConfig := web.LandingConfig{
@@ -223,7 +242,7 @@ func main() {
 	_ = srv.Shutdown(srvCtx)
 }
 
-func registerCollector(logger *slog.Logger, transport *http.Transport,
+func registerCollector(registerer prometheus.Registerer, logger *slog.Logger, transport *http.Transport,
 	addr string, labels map[string]string,
 ) {
 	var socketPath string
@@ -307,10 +326,10 @@ func registerCollector(logger *slog.Logger, transport *http.Transport,
 			os.Exit(1)
 		}
 		variableLabelNames := collector.NewVariableLabelNames(nil, nil, nil, nil, nil, nil, nil)
-		prometheus.MustRegister(collector.NewNginxPlusCollector(plusClient, "nginxplus", variableLabelNames, labels, logger))
+		mustRegister(registerer, collector.NewNginxPlusCollector(plusClient, "nginxplus", variableLabelNames, labels, logger))
 	} else {
 		ossClient := client.NewNginxClient(httpClient, addr)
-		prometheus.MustRegister(collector.NewNginxCollector(ossClient, "nginx", labels, logger))
+		mustRegister(registerer, collector.NewNginxCollector(ossClient, "nginx", labels, logger))
 	}
 }
 

exporter_test.go

@@ -6,6 +6,8 @@ import (
 	"time"
 
 	"github.com/alecthomas/kingpin/v2"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/collectors/version"
 	"github.com/prometheus/exporter-toolkit/web/kingpinflag"
 )
 
@@ -168,3 +170,61 @@ func TestConvertFlagToEnvar(t *testing.T) {
 		}
 	}
 }
+
+func TestNginxMetricsOnlyRegistry(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name                  string
+		nginxMetricsOnly      bool
+		wantVersionCollector  bool
+		wantDefaultCollectors bool
+	}{
+		{
+			name:                  "default behavior includes version and runtime collectors",
+			nginxMetricsOnly:      false,
+			wantVersionCollector:  true,
+			wantDefaultCollectors: true,
+		},
+		{
+			name:                  "web.nginx-metrics-only excludes version and runtime collectors",
+			nginxMetricsOnly:      true,
+			wantVersionCollector:  false,
+			wantDefaultCollectors: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			registry := prometheus.NewRegistry()
+
+			if !tt.nginxMetricsOnly {
+				// Register version collector like main() does when nginxMetricsOnly is false
+				if err := registry.Register(version.NewCollector("nginx_exporter")); err != nil {
+					t.Fatalf("failed to register version collector: %v", err)
+				}
+			}
+
+			// Gather metrics
+			metricFamilies, err := registry.Gather()
+			if err != nil {
+				t.Fatalf("failed to gather metrics: %v", err)
+			}
+
+			// Check for version collector metric
+			hasVersionMetric := false
+			for _, mf := range metricFamilies {
+				if mf.GetName() == "nginx_exporter_build_info" {
+					hasVersionMetric = true
+					break
+				}
+			}
+
+			if hasVersionMetric != tt.wantVersionCollector {
+				t.Errorf("version collector presence = %v, want %v", hasVersionMetric, tt.wantVersionCollector)
+			}
+		})
+	}
+}