Replace client and route counters by per-entry metrics.

This allows us to graph either per-connection or the total bandwidth
of the VPN server.

Fixes #2

openvpn_exporter.go

@@ -29,6 +29,17 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 )
 
+type OpenvpnServerHeader struct {
+	LabelColumns []string
+	Metrics      []OpenvpnServerHeaderField
+}
+
+type OpenvpnServerHeaderField struct {
+	Column    string
+	Desc      *prometheus.Desc
+	ValueType prometheus.ValueType
+}
+
 var (
 	// Metrics exported both for client and server statistics.
 	openvpnUpDesc = prometheus.NewDesc(
@@ -41,14 +52,52 @@ var (
 		[]string{"status_path"}, nil)
 
 	// Metrics specific to OpenVPN servers.
-	openvpnServerClientsDesc = prometheus.NewDesc(
-		prometheus.BuildFQName("openvpn", "server", "clients"),
-		"Number of clients connected to the OpenVPN server.",
-		[]string{"status_path"}, nil)
-	openvpnServerRoutesDesc = prometheus.NewDesc(
-		prometheus.BuildFQName("openvpn", "server", "routes"),
-		"Number of routes propagated by the OpenVPN server.",
-		[]string{"status_path"}, nil)
+	openvpnServerHeaders = map[string]OpenvpnServerHeader{
+		"CLIENT_LIST": OpenvpnServerHeader{
+			LabelColumns: []string{
+				"Common Name",
+				"Connected Since (time_t)",
+				"Real Address",
+				"Username",
+				"Virtual Address",
+			},
+			Metrics: []OpenvpnServerHeaderField{
+				OpenvpnServerHeaderField{
+					Column: "Bytes Received",
+					Desc: prometheus.NewDesc(
+						prometheus.BuildFQName("openvpn", "server", "client_received_bytes_total"),
+						"Amount of data received over a connection on the VPN server, in bytes.",
+						[]string{"status_path", "common_name", "connection_time", "real_address", "virtual_address", "username"}, nil),
+					ValueType: prometheus.CounterValue,
+				},
+				OpenvpnServerHeaderField{
+					Column: "Bytes Sent",
+					Desc: prometheus.NewDesc(
+						prometheus.BuildFQName("openvpn", "server", "client_sent_bytes_total"),
+						"Amount of data sent over a connection on the VPN server, in bytes.",
+						[]string{"status_path", "common_name", "connection_time", "real_address", "virtual_address", "username"}, nil),
+					ValueType: prometheus.CounterValue,
+				},
+			},
+		},
+		"ROUTING_TABLE": OpenvpnServerHeader{
+			LabelColumns: []string{
+				"Common Name",
+				"Real Address",
+				"Virtual Address",
+			},
+			Metrics: []OpenvpnServerHeaderField{
+				OpenvpnServerHeaderField{
+					Column: "Last Ref (time_t)",
+					Desc: prometheus.NewDesc(
+						prometheus.BuildFQName("openvpn", "server", "route_last_reference_time_seconds"),
+						"Time at which a route was last referenced, in seconds.",
+						[]string{"status_path", "common_name", "real_address", "virtual_address"}, nil),
+					ValueType: prometheus.GaugeValue,
+				},
+			},
+		},
+	}
 
 	// Metrics specific to OpenVPN clients.
 	openvpnClientDescs = map[string]*prometheus.Desc{
@@ -118,22 +167,16 @@ func CollectStatusFromReader(statusPath string, file io.Reader, ch chan<- promet
 func CollectServerStatusFromReader(statusPath string, file io.Reader, ch chan<- prometheus.Metric, separator string) error {
 	scanner := bufio.NewScanner(file)
 	scanner.Split(bufio.ScanLines)
-	clients := 0
-	routes := 0
+	headersFound := map[string][]string{}
 	for scanner.Scan() {
 		fields := strings.Split(scanner.Text(), separator)
-		if fields[0] == "CLIENT_LIST" {
-			// Per-client stats.
-			clients++
-		} else if fields[0] == "END" && len(fields) == 1 {
+		if fields[0] == "END" && len(fields) == 1 {
 			// Stats footer.
 		} else if fields[0] == "GLOBAL_STATS" {
 			// Global server statistics.
 		} else if fields[0] == "HEADER" && len(fields) > 2 {
 			// Column names for CLIENT_LIST and ROUTING_TABLE.
-		} else if fields[0] == "ROUTING_TABLE" {
-			// Per-route stats.
-			routes++
+			headersFound[fields[1]] = fields[2:]
 		} else if fields[0] == "TIME" && len(fields) == 3 {
 			// Time at which the statistics were updated.
 			time, err := strconv.ParseFloat(fields[2], 64)
@@ -147,20 +190,49 @@ func CollectServerStatusFromReader(statusPath string, file io.Reader, ch chan<-
 				statusPath)
 		} else if fields[0] == "TITLE" && len(fields) == 2 {
 			// OpenVPN version number.
+		} else if header, ok := openvpnServerHeaders[fields[0]]; ok {
+			// Entry that depends on a preceding HEADERS directive.
+			columnNames, ok := headersFound[fields[0]]
+			if !ok {
+				return fmt.Errorf("%s should be preceded by HEADERS", fields[0])
+			}
+			if len(fields) != len(columnNames)+1 {
+				return fmt.Errorf("HEADER for %s describes a different number of columns", fields[0])
+			}
+
+			// Store entry values in a map indexed by column name.
+			columnValues := map[string]string{}
+			for _, column := range header.LabelColumns {
+				columnValues[column] = ""
+			}
+			for i, column := range columnNames {
+				columnValues[column] = fields[i+1]
+			}
+
+			// Extract columns that should act as entry labels.
+			labels := []string{statusPath}
+			for _, column := range header.LabelColumns {
+				labels = append(labels, columnValues[column])
+			}
+
+			// Export relevant columns as individual metrics.
+			for _, metric := range header.Metrics {
+				if columnValue, ok := columnValues[metric.Column]; ok {
+					value, err := strconv.ParseFloat(columnValue, 64)
+					if err != nil {
+						return err
+					}
+					ch <- prometheus.MustNewConstMetric(
+						metric.Desc,
+						metric.ValueType,
+						value,
+						labels...)
+				}
+			}
 		} else {
 			return fmt.Errorf("Unsupported key: %q", fields[0])
 		}
 	}
-	ch <- prometheus.MustNewConstMetric(
-		openvpnServerClientsDesc,
-		prometheus.GaugeValue,
-		float64(clients),
-		statusPath)
-	ch <- prometheus.MustNewConstMetric(
-		openvpnServerRoutesDesc,
-		prometheus.GaugeValue,
-		float64(routes),
-		statusPath)
 	return scanner.Err()
 }