Support IPv6 for UDP rsyslog listener on gorouter

[mike-jc]

Description

Allow syslog-release to listen to UDP on IPv4 and IPv6 (if available). The change enables it to listen on all available loopback interfaces; the name localhost is resolved based on the'/etc/hosts' file. If IPv6 is available, the IPv6 loopback address ([::1]) will also be resolved; if not, it will not. No change in behavior for IPv4.

Type of change

• Bug fix (non-breaking change which fixes an issue)

Testing performed?

• Integration tests

[peanball]

We tested this on a dev environment.

The UDP listeners look like this on a noble stemcell gorouter VM:

router/c59225db-2712-4993-885e-4d600ea5fd0a:~# lsof -i UDP:514
COMMAND   PID   USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
gorouter 6851   vcap    9u  IPv6 320129      0t0  UDP e9456bf0-21ef-4260-83c3-321b221a4862:43071->e9456bf0-21ef-4260-83c3-321b221a4862:syslog
rsyslogd 8617 syslog    6u  IPv6 418345      0t0  UDP e9456bf0-21ef-4260-83c3-321b221a4862:syslog
rsyslogd 8617 syslog    7u  IPv4 418346      0t0  UDP e9456bf0-21ef-4260-83c3-321b221a4862:syslog

We have Gorouter logging via syslog, and you can see the connection is handled via IPv6 on the loopback device.

UDP listeners are active on IPv4 and IPv6.