Hello! We upgraded a Windows Tomcat instance from 8.5.41 to 8.5.84. This Tomcat
instance is behind a load balancer. Since the upgrade the Tomcat access log
(AccessLogValve) has an "empty" entry with response 400 for every TCP half-open
health check from the load balancer. Because the health check is every 5
seconds from redundant load-balancers we are getting quite alot of junk in the
access log. The TCP half-open check is:LB --> SYN --> Tomcat 443LB <--
SYN/ACK <-- Tomcat 443LB --> FIN --> Tomcat 443LB <-- FIN/ACK <-- Tomcat
443Access log excerpt:[03/May/2023:00:13:58 +0200] 10.20.10.2 - "-" - "-" "-"
400 0 - -[03/May/2023:00:13:59 +0200] 10.20.10.3 - "-" - "-" "-" 400 0 -
-[03/May/2023:00:14:03 +0200] 10.20.10.2 - "-" - "-" "-" 400 0 -
-[03/May/2023:00:14:04 +0200] 10.20.10.3 - "-" - "-" "-" 400 0 -
-[03/May/2023:00:14:08 +0200] 10.20.10.2 - "-" - "-" "-" 400 0 -
-[03/May/2023:00:14:09 +0200] 10.20.10.3 - "-" - "-" "-" 400 0 -
-[03/May/2023:00:14:13 +0200] 10.20.10.2 - "-" - "-" "-" 400 0 - -
We can reproduce this effect from Windows Powershell with:Test-NetConnection
-ComputerName tomcat.server.name -RemotePort 443
My question is, is this expected behaviour? Is TCP half-open health check
supported by Tomcat?
Thanks for any help.Paul
