When upgrading the agent from 9.1 to 10, it is noticed that if host names were returned in capital letters in 9.1, they are returned in lower case in 10.1
With version 9.1.6 we had under Backends
- System ABC1234 on port 12345
With version 10.1 we had under Backends
- System abc1234 on port 12345
This can also affect the host name the agent reports under in the Investigator tree.
This has an impact on metric groupings as they are case-sensitive so would not match if the case of the hostname changes.
Customer upgrading Java agents from 9.1.6 to 10.1, having already upgraded Enterprise Manager cluster to 10.1 and not seeing a change in behaviour after cluster upgrade.
The agent DNS service which obtains the hostnames of agents and remote systems has been designed, since APM 9.7, to return all hostnames in lower case.
So this specifically affects agent upgrades.
For metric groupings to function, anywhere that a hostname has been specified in upper case should be modified to lower-case.
If you have a period where you are upgrading agent but the old agent could still be reporting from same host, or you have the older agent monitoring an application that could show up as a remote system with a hostname with capital letters (System ABC1234 on port 12345)
you can use a logical OR in regex, for example: