add tcp connections stat plugin.

plugins/system/ps.go

@@ -32,6 +32,7 @@ type PS interface {
 	VMStat() (*mem.VirtualMemoryStat, error)
 	SwapStat() (*mem.SwapMemoryStat, error)
 	DockerStat() ([]*DockerContainerStat, error)
+	NetConnections() ([]net.NetConnectionStat, error)
 }
 
 func add(acc plugins.Accumulator,
@@ -90,6 +91,10 @@ func (s *systemPS) NetIO() ([]net.NetIOCountersStat, error) {
 	return net.NetIOCounters(true)
 }
 
+func (s *systemPS) NetConnections() ([]net.NetConnectionStat, error) {
+	return net.NetConnections("all")
+}
+
 func (s *systemPS) DiskIO() (map[string]disk.DiskIOCountersStat, error) {
 	m, err := disk.DiskIOCounters()
 	if err == common.NotImplementedError {

plugins/system/tcpconn.go

@@ -0,0 +1,60 @@
+package system
+
+import (
+	"fmt"
+
+	"github.com/influxdb/telegraf/plugins"
+)
+
+type TCPConnectionStats struct {
+	ps PS
+}
+
+func (_ *TCPConnectionStats) Description() string {
+	return "Read metrics about TCP status such as established, time wait etc"
+}
+
+var tcpstatSampleConfig = ""
+
+func (_ *TCPConnectionStats) SampleConfig() string {
+	return tcpstatSampleConfig
+}
+
+func (s *TCPConnectionStats) Gather(acc plugins.Accumulator) error {
+	netconns, err := s.ps.NetConnections()
+	if err != nil {
+		return fmt.Errorf("error getting net connections info: %s", err)
+	}
+	counts := make(map[string]int)
+
+	// TODO: add family to tags or else
+	tags := map[string]string{}
+	for _, netcon := range netconns {
+		c, ok := counts[netcon.Status]
+		if !ok {
+			counts[netcon.Status] = 0
+		}
+		counts[netcon.Status] = c + 1
+	}
+
+	acc.Add("established", counts["ESTABLISHED"], tags)
+	acc.Add("syn_sent", counts["SYN_SENT"], tags)
+	acc.Add("syn_recv", counts["SYN_RECV"], tags)
+	acc.Add("fin_wait1", counts["FIN_WAIT1"], tags)
+	acc.Add("fin_wait2", counts["FIN_WAIT2"], tags)
+	acc.Add("time_wait", counts["TIME_WAIT"], tags)
+	acc.Add("close", counts["CLOSE"], tags)
+	acc.Add("close_wait", counts["CLOSE_WAIT"], tags)
+	acc.Add("last_ack", counts["LAST_ACK"], tags)
+	acc.Add("listen", counts["LISTEN"], tags)
+	acc.Add("closing", counts["CLOSING"], tags)
+	acc.Add("none", counts["NONE"], tags)
+
+	return nil
+}
+
+func init() {
+	plugins.Add("tcpconn", func() plugins.Plugin {
+		return &TCPConnectionStats{ps: &systemPS{}}
+	})
+}