Add packets per second metric

- Related: #10

agent/main.go

@@ -52,7 +52,8 @@ func main() {
 	}
 
 	agent := lbagent.New(os.Args[1], nil, dialer)
-	registerBwmon(agent, config)
+	registerBandwidth(agent, config)
+	registerPackets(agent, config)
 	agent.RegisterUtilization("conntrack", lbpb.Utilization_GAUGE, conntrackUtilization)
 
 	agent.SetUpdateInterval(updateInterval)
@@ -66,7 +67,7 @@ func main() {
 	}
 }
 
-func registerBwmon(agent *lbagent.Agent, config Config) {
+func registerBandwidth(agent *lbagent.Agent, config Config) {
 	txBandwidth := config.TxBandwidth
 	if txBandwidth == 0 {
 		txBandwidth = config.Bandwidth
@@ -81,3 +82,11 @@ func registerBwmon(agent *lbagent.Agent, config Config) {
 	rxBwFunc := getBandwidthUtilization(config.NetDevice, rxBandwidth, RX)
 	agent.RegisterUtilization("bandwidth_rx", lbpb.Utilization_GAUGE, rxBwFunc)
 }
+
+func registerPackets(agent *lbagent.Agent, config Config) {
+	txPacketsFunc := getPacketUtilization(config.NetDevice, TX)
+	agent.RegisterUtilization("packets_tx", lbpb.Utilization_COUNTER, txPacketsFunc)
+
+	rxPacketsFunc := getPacketUtilization(config.NetDevice, RX)
+	agent.RegisterUtilization("packets_rx", lbpb.Utilization_COUNTER, rxPacketsFunc)
+}

agent/bwmon.go → agent/net.go

@@ -36,7 +36,11 @@ const (
 func getBandwidthUtilization(device string, max int64, direction int) func() float64 {
 	var lastRead uint64
 	return func() float64 {
-		n, err := parseProcNetDev(device, direction)
+		field := 1
+		if direction == TX {
+			field = 9
+		}
+		n, err := parseProcNetDev(device, field)
 		if err != nil {
 			log.Printf("Error reading /proc/net/dev: %v", err)
 			lastRead = 0
@@ -55,7 +59,22 @@ func getBandwidthUtilization(device string, max int64, direction int) func() flo
 	}
 }
 
-func parseProcNetDev(dev string, direction int) (uint64, error) {
+func getPacketUtilization(device string, direction int) func() float64 {
+	return func() float64 {
+		field := 2
+		if direction == TX {
+			field = 10
+		}
+		n, err := parseProcNetDev(device, field)
+		if err != nil {
+			log.Printf("Error reading /proc/net/dev: %v", err)
+			return 0
+		}
+		return float64(n)
+	}
+}
+
+func parseProcNetDev(dev string, field int) (uint64, error) {
 	file, err := os.Open("/proc/net/dev")
 	if err != nil {
 		return 0, err
@@ -65,18 +84,11 @@ func parseProcNetDev(dev string, direction int) (uint64, error) {
 	// Device name (+ ':') in field 0
 	devCol := []byte(dev + ":")
 
-	// Receive bytes: field 1
-	// Transmit bytes: field 9
-	counterIndex := 1
-	if direction == TX {
-		counterIndex = 9
-	}
-
 	input := bufio.NewScanner(file)
 	for input.Scan() {
 		fields := bytes.Fields(input.Bytes())
 		if bytes.Equal(fields[0], devCol) {
-			n, err := strconv.ParseUint(string(fields[counterIndex]), 10, 64)
+			n, err := strconv.ParseUint(string(fields[field]), 10, 64)
 			if err != nil {
 				return 0, err
 			}

lb.go

@@ -42,6 +42,16 @@ var limits = []*lb.Limit{
 		Min:       0,
 		Max:       1,
 	},
+	{
+		Dimension: "packets_tx",
+		Min:       0,
+		Max:       100_000,
+	},
+	{
+		Dimension: "packets_rx",
+		Min:       0,
+		Max:       100_000,
+	},
 	{
 		Dimension: "conntrack",
 		Min:       0,