feat: ability to disable per client metrics

As the common_name can have a high cardinality on high traffic
openvpn servers with a lot of clients, this allows to drop that
metric and only expose metrics with a lower cardinality

Author: patrickjahns

pkg/collector/openvpn.go

@@ -12,6 +12,7 @@ type OpenVPNCollector struct {
 	logger                log.Logger
 	name                  string
 	statusFile            string
+	collectClientMetrics  bool
 	LastUpdated           *prometheus.Desc
 	ConnectedClients      *prometheus.Desc
 	BytesReceived         *prometheus.Desc
@@ -21,11 +22,12 @@ type OpenVPNCollector struct {
 }
 
 // NewOpenVPNCollector returns a new OpenVPNCollector
-func NewOpenVPNCollector(logger log.Logger, name string, statusFile string) *OpenVPNCollector {
+func NewOpenVPNCollector(logger log.Logger, name string, statusFile string, collectClientMetrics bool) *OpenVPNCollector {
 	return &OpenVPNCollector{
-		logger:     logger,
-		statusFile: statusFile,
-		name:       name,
+		logger:               logger,
+		statusFile:           statusFile,
+		name:                 name,
+		collectClientMetrics: collectClientMetrics,
 
 		LastUpdated: prometheus.NewDesc(
 			prometheus.BuildFQName(namespace, "", "last_updated"),
@@ -70,10 +72,12 @@ func NewOpenVPNCollector(logger log.Logger, name string, statusFile string) *Ope
 func (c *OpenVPNCollector) Describe(ch chan<- *prometheus.Desc) {
 	ch <- c.LastUpdated
 	ch <- c.ConnectedClients
-	ch <- c.BytesSent
-	ch <- c.BytesReceived
-	ch <- c.ConnectedSince
 	ch <- c.MaxBcastMcastQueueLen
+	if c.collectClientMetrics {
+		ch <- c.BytesSent
+		ch <- c.BytesReceived
+		ch <- c.ConnectedSince
+	}
 }
 
 // Collect is called by the Prometheus registry when collecting metrics.
@@ -100,24 +104,26 @@ func (c *OpenVPNCollector) Collect(ch chan<- prometheus.Metric) {
 			"bytesReceived", client.BytesReceived,
 			"bytesSent", client.BytesSent,
 		)
-		ch <- prometheus.MustNewConstMetric(
-			c.BytesReceived,
-			prometheus.GaugeValue,
-			client.BytesReceived,
-			c.name, client.CommonName,
-		)
-		ch <- prometheus.MustNewConstMetric(
-			c.BytesSent,
-			prometheus.GaugeValue,
-			client.BytesSent,
-			c.name, client.CommonName,
-		)
-		ch <- prometheus.MustNewConstMetric(
-			c.ConnectedSince,
-			prometheus.GaugeValue,
-			float64(client.ConnectedSince.Unix()),
-			c.name, client.CommonName,
-		)
+		if c.collectClientMetrics {
+			ch <- prometheus.MustNewConstMetric(
+				c.BytesReceived,
+				prometheus.GaugeValue,
+				client.BytesReceived,
+				c.name, client.CommonName,
+			)
+			ch <- prometheus.MustNewConstMetric(
+				c.BytesSent,
+				prometheus.GaugeValue,
+				client.BytesSent,
+				c.name, client.CommonName,
+			)
+			ch <- prometheus.MustNewConstMetric(
+				c.ConnectedSince,
+				prometheus.GaugeValue,
+				float64(client.ConnectedSince.Unix()),
+				c.name, client.CommonName,
+			)
+		}
 	}
 	level.Debug(c.logger).Log(
 		"updatedAt", status.UpdatedAt,

pkg/command/command.go

@@ -68,10 +68,15 @@ func Run() error {
 			Usage:    "The OpenVPN status file(s) to export (example test:./example/version1.status )",
 			Required: true,
 		},
+		&cli.BoolFlag{
+			Name:  "disable-client-metrics",
+			Usage: "Disables per client (bytes_received, bytes_sent, connected_since) metrics",
+		},
 	}
 
 	app.Before = func(c *cli.Context) error {
-		cfg.StatusFile = c.StringSlice("status-file")
+		cfg.StatusCollector.StatusFile = c.StringSlice("status-file")
+		cfg.StatusCollector.ExportClientMetrics = !c.Bool("disable-client-metrics")
 		return nil
 	}
 
@@ -105,7 +110,7 @@ func run(c *cli.Context, cfg *config.Config) error {
 		version.GoVersion,
 		version.Started,
 	))
-	for _, statusFile := range cfg.StatusFile {
+	for _, statusFile := range cfg.StatusCollector.StatusFile {
 		serverName, statusFile := parseStatusFileSlice(statusFile)
 
 		level.Info(logger).Log(
@@ -117,6 +122,7 @@ func run(c *cli.Context, cfg *config.Config) error {
 			logger,
 			serverName,
 			statusFile,
+			cfg.StatusCollector.ExportClientMetrics,
 		))
 	}
 

pkg/config/config.go

@@ -14,9 +14,15 @@ type Logs struct {
 
 // Config defines the general configuration object
 type Config struct {
-	Server     Server
-	Logs       Logs
-	StatusFile []string
+	Server          Server
+	Logs            Logs
+	StatusCollector StatusCollector
+}
+
+// StatusCollector contains configuration for the OpenVPN status collector
+type StatusCollector struct {
+	ExportClientMetrics bool
+	StatusFile          []string
 }
 
 // Load initializes a default configuration struct.