Add prefix to nats metrics with -prefix

README.md

@@ -55,6 +55,8 @@ Usage of ./prometheus-nats-exporter:
     	URL path from which to serve scrapes. (default "/metrics")
   -port int
     	Port to listen on. (default 7777)
+  -prefix
+    	Set the prefix for all the metrics.
   -r string
     	Remote syslog address to write log statements.
   -remote_syslog string

collector/collector.go

@@ -23,9 +23,7 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 )
 
-const (
-	namespace = "gnatsd"
-)
+var namespace = "gnatsd"
 
 // CollectedServer is a NATS server polled by this collector
 type CollectedServer struct {
@@ -46,10 +44,13 @@ type NATSCollector struct {
 // Based on our current integration, we're going to treat all metrics as gauges.
 // We are going to call the set message on the gauge when we receive an updated
 // metrics pull.
-func newPrometheusGaugeVec(subsystem string, name string, help string) (metric *prometheus.GaugeVec) {
+func newPrometheusGaugeVec(subsystem string, name string, help string, prefix string) (metric *prometheus.GaugeVec) {
 	if help == "" {
 		help = name
 	}
+	if prefix != "" {
+		namespace = prefix
+	}
 	opts := prometheus.GaugeOpts{
 		Namespace: namespace,
 		Subsystem: subsystem,
@@ -162,7 +163,7 @@ func (nc *NATSCollector) Collect(ch chan<- prometheus.Metric) {
 // For each NATS Metrics endpoint (/*z) get the first URL
 // to determine the list of possible metrics.
 // TODO: flatten embedded maps.
-func (nc *NATSCollector) initMetricsFromServers() {
+func (nc *NATSCollector) initMetricsFromServers(namespace string) {
 	var response map[string]interface{}
 
 	nc.Stats = make(map[string]interface{})
@@ -191,7 +192,7 @@ func (nc *NATSCollector) initMetricsFromServers() {
 			i := response[k]
 			switch v := i.(type) {
 			case float64: // all json numbers are handled here.
-				nc.Stats[k] = newPrometheusGaugeVec(nc.endpoint, k, "")
+				nc.Stats[k] = newPrometheusGaugeVec(nc.endpoint, k, "", namespace)
 			case string:
 				// do nothing
 			default:
@@ -204,7 +205,7 @@ func (nc *NATSCollector) initMetricsFromServers() {
 
 // NewCollector creates a new NATS Collector from a list of monitoring URLs.
 // Each URL should be to a specific endpoint (e.g. varz, connz, subsz, or routez)
-func NewCollector(endpoint string, servers []*CollectedServer) prometheus.Collector {
+func NewCollector(endpoint string, servers []*CollectedServer, namespace string) prometheus.Collector {
 	if isStreamingEndpoint(endpoint) {
 		return newStreamingCollector(endpoint, servers)
 	}
@@ -230,7 +231,7 @@ func NewCollector(endpoint string, servers []*CollectedServer) prometheus.Collec
 		}
 	}
 
-	nc.initMetricsFromServers()
+	nc.initMetricsFromServers(namespace)
 
 	return nc
 }

collector/collector_test.go

@@ -38,7 +38,7 @@ func verifyCollector(url string, endpoint string, cases map[string]float64, t *t
 		ID:  "id",
 		URL: url,
 	}
-	coll := NewCollector(endpoint, servers)
+	coll := NewCollector(endpoint, servers, "test")
 
 	// now collect the metrics
 	c := make(chan prometheus.Metric)
@@ -116,7 +116,7 @@ func getLabelValues(url string, endpoint string, metricNames []string) (map[stri
 		ID:  "id",
 		URL: url,
 	}
-	coll := NewCollector(endpoint, servers)
+	coll := NewCollector(endpoint, servers, "test")
 	coll.Collect(metrics)
 	close(metrics)
 
@@ -202,10 +202,10 @@ func TestRegister(t *testing.T) {
 	// check duplicates do not panic
 	servers = append(servers, cs)
 
-	NewCollector("varz", servers)
+	NewCollector("varz", servers, "test")
 
 	// test idenpotency.
-	nc := NewCollector("varz", servers)
+	nc := NewCollector("varz", servers, "test")
 
 	// test without a server (no error).
 	if err := prometheus.Register(nc); err == nil {
@@ -218,14 +218,14 @@ func TestRegister(t *testing.T) {
 	defer s.Shutdown()
 
 	// test collect with a server
-	nc = NewCollector("varz", servers)
+	nc = NewCollector("varz", servers, "test")
 	if err := prometheus.Register(nc); err != nil {
 		t.Fatalf("Got unexpected error: %v", err)
 	}
 	prometheus.Unregister(nc)
 
 	// test collect with an invalid endpoint
-	nc = NewCollector("GARBAGE", servers)
+	nc = NewCollector("GARBAGE", servers, "test")
 	if err := prometheus.Register(nc); err == nil {
 		t.Fatalf("Did not get expected error.")
 		defer prometheus.Unregister(nc)

exporter/exporter.go

@@ -52,6 +52,7 @@ type NATSExporterOptions struct {
 	NATSServerTag        string
 	HTTPUser             string // User in metrics scrape by prometheus.
 	HTTPPassword         string
+	Prefix               string
 }
 
 //NATSExporter collects NATS metrics
@@ -108,7 +109,7 @@ func NewExporter(opts *NATSExporterOptions) *NATSExporter {
 }
 
 func (ne *NATSExporter) createCollector(endpoint string) {
-	ne.registerCollector(endpoint, collector.NewCollector(endpoint, ne.servers))
+	ne.registerCollector(endpoint, collector.NewCollector(endpoint, ne.servers, ne.opts.Prefix))
 }
 
 func (ne *NATSExporter) registerCollector(endpoint string, nc prometheus.Collector) {

prometheus_nats_exporter.go

@@ -117,6 +117,7 @@ func main() {
 	flag.StringVar(&opts.CaFile, "tlscacert", "", "Client certificate CA for verification (used with HTTPS).")
 	flag.StringVar(&opts.HTTPUser, "http_user", "", "Enable basic auth and set user name for HTTP scrapes.")
 	flag.StringVar(&opts.HTTPPassword, "http_pass", "", "Set the password for HTTP scrapes. NATS bcrypt supported.")
+	flag.StringVar(&opts.Prefix, "prefix", "", "Set the prefix for all the metrics.")
 	flag.Parse()
 
 	opts.RetryInterval = time.Duration(retryInterval) * time.Second