Add TCPTimeouts to netstat default filter (#2189)

TCP timeouts count is a useful signal to show
abnormal network performance and is another
signal to aid debugging. This metric can be
used to generate proactive alerts for host
network namespace workloads.

Signed-off-by: Martin Kennelly <mkennell@redhat.com>

CHANGELOG.md

@@ -5,6 +5,7 @@
 * [ENHANCEMENT]
 * [BUGFIX]
 
+  [CHANGE] Add TCPTimeouts to netstat default filter #2189
 * [ENHANCEMENT] Add flag to disable guest CPU metrics #2123
 * [ENHANCEMENT] Add DMI collector #303
 * [BUGFIX] Fix possible panic on macOS #2133

collector/fixtures/e2e-output.txt

@@ -2240,6 +2240,9 @@ node_netstat_TcpExt_SyncookiesRecv 0
 # HELP node_netstat_TcpExt_SyncookiesSent Statistic TcpExtSyncookiesSent.
 # TYPE node_netstat_TcpExt_SyncookiesSent untyped
 node_netstat_TcpExt_SyncookiesSent 0
+# HELP node_netstat_TcpExt_TCPTimeouts Statistic TcpExtTCPTimeouts.
+# TYPE node_netstat_TcpExt_TCPTimeouts untyped
+node_netstat_TcpExt_TCPTimeouts 115
 # HELP node_netstat_Tcp_ActiveOpens Statistic TcpActiveOpens.
 # TYPE node_netstat_Tcp_ActiveOpens untyped
 node_netstat_Tcp_ActiveOpens 3556

collector/netstat_linux.go

@@ -36,7 +36,7 @@ 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|OutRsts|PassiveOpens|RetransSegs|CurrEstab)|Udp6?_(InDatagrams|OutDatagrams|NoPorts|RcvbufErrors|SndbufErrors))$").String()
+	netStatFields = kingpin.Flag("collector.netstat.fields", "Regexp of fields to return for netstat collector.").Default("^(.*_(InErrors|InErrs)|Ip_Forwarding|Ip(6|Ext)_(InOctets|OutOctets)|Icmp6?_(InMsgs|OutMsgs)|TcpExt_(Listen.*|Syncookies.*|TCPSynRetrans|TCPTimeouts)|Tcp_(ActiveOpens|InSegs|OutSegs|OutRsts|PassiveOpens|RetransSegs|CurrEstab)|Udp6?_(InDatagrams|OutDatagrams|NoPorts|RcvbufErrors|SndbufErrors))$").String()
 )
 
 type netStatCollector struct {