Add TCPOFOQueue to default netstat metrics

Adds a count for TCP packets received out of orders. This can be an indication that there is packet loss on the way packets travel towards this server. In that case, the sender will retransmit (and we can already monitor the Tcp_RetransSegs there), but we have no way to monitor the packet loss on the receiver side. When a packet is received and the receiver detects previous one missing, it will increase the TCPOFOQueue counter and reply with selective ACK to the sender, both possible indications of packet loss. Confirmation of packet loss can be achieved by taking packet captures, ignoring wireshark analysis, and carefully looking at data being retransmitted based on the TCP seq. Just like RetransSegs, TCPOFOQueue should be interesting for any deployment as a mean to detect packet loss, so here suggesting adding it to the default list. Signed-off-by: François Rigault <frigo@amadeus.com>
prometheus · Dec 2, 2023 · 67525d3 · 67525d3
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commit 67525d3
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diff --git a/collector/fixtures/e2e-output.txt b/collector/fixtures/e2e-output.txt
@@ -2325,6 +2325,9 @@ 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_TCPOFOQueue Statistic TcpExtTCPOFOQueue.
+# TYPE node_netstat_TcpExt_TCPOFOQueue untyped
+node_netstat_TcpExt_TCPOFOQueue 42
 # HELP node_netstat_TcpExt_TCPTimeouts Statistic TcpExtTCPTimeouts.
 # TYPE node_netstat_TcpExt_TCPTimeouts untyped
 node_netstat_TcpExt_TCPTimeouts 115

diff --git a/collector/fixtures/proc/net/netstat b/collector/fixtures/proc/net/netstat
@@ -1,4 +1,4 @@
-TcpExt: SyncookiesSent SyncookiesRecv SyncookiesFailed EmbryonicRsts PruneCalled RcvPruned OfoPruned OutOfWindowIcmps LockDroppedIcmps ArpFilter TW TWRecycled TWKilled PAWSPassive PAWSActive PAWSEstab DelayedACKs DelayedACKLocked DelayedACKLost ListenOverflows ListenDrops TCPPrequeued TCPDirectCopyFromBacklog TCPDirectCopyFromPrequeue TCPPrequeueDropped TCPHPHits TCPHPHitsToUser TCPPureAcks TCPHPAcks TCPRenoRecovery TCPSackRecovery TCPSACKReneging TCPFACKReorder TCPSACKReorder TCPRenoReorder TCPTSReorder TCPFullUndo TCPPartialUndo TCPDSACKUndo TCPLossUndo TCPLoss TCPLostRetransmit TCPRenoFailures TCPSackFailures TCPLossFailures TCPFastRetrans TCPForwardRetrans TCPSlowStartRetrans TCPTimeouts TCPRenoRecoveryFail TCPSackRecoveryFail TCPSchedulerFailed TCPRcvCollapsed TCPDSACKOldSent TCPDSACKOfoSent TCPDSACKRecv TCPDSACKOfoRecv TCPAbortOnData TCPAbortOnClose TCPAbortOnMemory TCPAbortOnTimeout TCPAbortOnLinger TCPAbortFailed TCPMemoryPressures TCPSACKDiscard TCPDSACKIgnoredOld TCPDSACKIgnoredNoUndo TCPSpuriousRTOs TCPMD5NotFound TCPMD5Unexpected TCPSackShifted TCPSackMerged TCPSackShiftFallback TCPBacklogDrop TCPMinTTLDrop TCPDeferAcceptDrop IPReversePathFilter TCPTimeWaitOverflow TCPReqQFullDoCookies TCPReqQFullDrop TCPChallengeACK TCPSYNChallenge
-TcpExt: 0 0 2 0 0 0 0 0 0 0 388812 0 0 0 0 6 102471 17 9 0 0 80568 0 168808 0 4471289 26 1433940 3744565 0 1 0 0 0 0 0 0 0 0 48 0 0 0 1 0 1 0 1 115 0 0 0 0 9 0 5 0 41 4 0 0 0 0 0 0 0 1 0 0 0 0 2 5 0 0 0 0 0 0 0 2 2
+TcpExt: SyncookiesSent SyncookiesRecv SyncookiesFailed EmbryonicRsts PruneCalled RcvPruned OfoPruned OutOfWindowIcmps LockDroppedIcmps ArpFilter TW TWRecycled TWKilled PAWSPassive PAWSActive PAWSEstab DelayedACKs DelayedACKLocked DelayedACKLost ListenOverflows ListenDrops TCPPrequeued TCPDirectCopyFromBacklog TCPDirectCopyFromPrequeue TCPPrequeueDropped TCPHPHits TCPHPHitsToUser TCPPureAcks TCPHPAcks TCPRenoRecovery TCPSackRecovery TCPSACKReneging TCPFACKReorder TCPSACKReorder TCPRenoReorder TCPTSReorder TCPFullUndo TCPPartialUndo TCPDSACKUndo TCPLossUndo TCPLoss TCPLostRetransmit TCPRenoFailures TCPSackFailures TCPLossFailures TCPFastRetrans TCPForwardRetrans TCPSlowStartRetrans TCPTimeouts TCPRenoRecoveryFail TCPSackRecoveryFail TCPSchedulerFailed TCPRcvCollapsed TCPDSACKOldSent TCPDSACKOfoSent TCPDSACKRecv TCPDSACKOfoRecv TCPAbortOnData TCPAbortOnClose TCPAbortOnMemory TCPAbortOnTimeout TCPAbortOnLinger TCPAbortFailed TCPMemoryPressures TCPSACKDiscard TCPDSACKIgnoredOld TCPDSACKIgnoredNoUndo TCPSpuriousRTOs TCPMD5NotFound TCPMD5Unexpected TCPSackShifted TCPSackMerged TCPSackShiftFallback TCPBacklogDrop TCPMinTTLDrop TCPDeferAcceptDrop IPReversePathFilter TCPTimeWaitOverflow TCPReqQFullDoCookies TCPReqQFullDrop TCPChallengeACK TCPSYNChallenge TCPOFOQueue
+TcpExt: 0 0 2 0 0 0 0 0 0 0 388812 0 0 0 0 6 102471 17 9 0 0 80568 0 168808 0 4471289 26 1433940 3744565 0 1 0 0 0 0 0 0 0 0 48 0 0 0 1 0 1 0 1 115 0 0 0 0 9 0 5 0 41 4 0 0 0 0 0 0 0 1 0 0 0 0 2 5 0 0 0 0 0 0 0 2 2 42
 IpExt: InNoRoutes InTruncatedPkts InMcastPkts OutMcastPkts InBcastPkts OutBcastPkts InOctets OutOctets InMcastOctets OutMcastOctets InBcastOctets OutBcastOctets
 IpExt: 0 0 0 0 0 0 6286396970 2786264347 0 0 0 0
diff --git a/collector/netstat_linux.go b/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|TCPTimeouts)|Tcp_(ActiveOpens|InSegs|OutSegs|OutRsts|PassiveOpens|RetransSegs|CurrEstab)|Udp6?_(InDatagrams|OutDatagrams|NoPorts|RcvbufErrors|SndbufErrors))$").String()
+	netStatFields = kingpin.Flag("collector.netstat.fields", "Regexp of fields to return for netstat collector.").Default("^(.*_(InErrors|InErrs)|Ip_Forwarding|Ip(6|Ext)_(InOctets|OutOctets)|Icmp6?_(InMsgs|OutMsgs)|TcpExt_(Listen.*|Syncookies.*|TCPSynRetrans|TCPTimeouts|TCPOFOQueue)|Tcp_(ActiveOpens|InSegs|OutSegs|OutRsts|PassiveOpens|RetransSegs|CurrEstab)|Udp6?_(InDatagrams|OutDatagrams|NoPorts|RcvbufErrors|SndbufErrors))$").String()
 )
 
 type netStatCollector struct {