Include TCP OutRsts in netstat metrics

TCP "OutRsts" is the number of TCP Resets sent by the node. This can be
useful for monitoring connection failures and flooding.

Signed-off-by: Ben Kochie <superq@gmail.com>

Author: SuperQ

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 * [CHANGE]
 * [FEATURE]
-* [ENHANCEMENT]
+* [ENHANCEMENT] Include TCP OutRsts in netstat metrics
 * [BUGFIX]
 
 ## 1.0.0 / 2020-05-25

collector/fixtures/e2e-64k-page-output.txt

@@ -1886,6 +1886,9 @@ node_netstat_Tcp_InErrs 5
 # HELP node_netstat_Tcp_InSegs Statistic TcpInSegs.
 # TYPE node_netstat_Tcp_InSegs untyped
 node_netstat_Tcp_InSegs 5.7252008e+07
+# HELP node_netstat_Tcp_OutRsts Statistic TcpOutRsts.
+# TYPE node_netstat_Tcp_OutRsts untyped
+node_netstat_Tcp_OutRsts 1003
 # HELP node_netstat_Tcp_OutSegs Statistic TcpOutSegs.
 # TYPE node_netstat_Tcp_OutSegs untyped
 node_netstat_Tcp_OutSegs 5.4915039e+07

collector/fixtures/e2e-output.txt

@@ -1955,6 +1955,9 @@ node_netstat_Tcp_InErrs 5
 # HELP node_netstat_Tcp_InSegs Statistic TcpInSegs.
 # TYPE node_netstat_Tcp_InSegs untyped
 node_netstat_Tcp_InSegs 5.7252008e+07
+# HELP node_netstat_Tcp_OutRsts Statistic TcpOutRsts.
+# TYPE node_netstat_Tcp_OutRsts untyped
+node_netstat_Tcp_OutRsts 1003
 # HELP node_netstat_Tcp_OutSegs Statistic TcpOutSegs.
 # TYPE node_netstat_Tcp_OutSegs untyped
 node_netstat_Tcp_OutSegs 5.4915039e+07

collector/netstat_linux.go

@@ -34,7 +34,7 @@ const (
 )
 
 var (
-	netStatFields = kingpin.Flag("collector.netstat.fields", "Regexp of fields to return for netstat collector.").Default("^(.*_(InErrors|InErrs)|Ip_Forwarding|Ip(6|Ext)_(InOctets|OutOctets)|Icmp6?_(InMsgs|OutMsgs)|TcpExt_(Listen.*|Syncookies.*|TCPSynRetrans)|Tcp_(ActiveOpens|InSegs|OutSegs|PassiveOpens|RetransSegs|CurrEstab)|Udp6?_(InDatagrams|OutDatagrams|NoPorts|RcvbufErrors|SndbufErrors))$").String()
+	netStatFields = kingpin.Flag("collector.netstat.fields", "Regexp of fields to return for netstat collector.").Default("^(.*_(InErrors|InErrs)|Ip_Forwarding|Ip(6|Ext)_(InOctets|OutOctets)|Icmp6?_(InMsgs|OutMsgs)|TcpExt_(Listen.*|Syncookies.*|TCPSynRetrans)|Tcp_(ActiveOpens|InSegs|OutSegs|OutRsts|PassiveOpens|RetransSegs|CurrEstab)|Udp6?_(InDatagrams|OutDatagrams|NoPorts|RcvbufErrors|SndbufErrors))$").String()
 )
 
 type netStatCollector struct {