I seem to be seeing unexpected behaviour using dynamic DNS resolution - any help or advice you can offer would be much appreciated.
I keep seeing messages like this in the log:
Server backend_name/server_name is going DOWN for maintenance (DNS timeout status). 0 active and 0 backup servers left. 0 sessions active, 0 requeued, 0 remaining in queue.
Running a tcpdump on the DNS queries haproxy generates, I typically see successful DNS responses less than 3 seconds before seeing this error. Often I will see this message 3s before the one above (even with a
hold valid value of
30s), I also see it when the server is apparently marked as DOWN:
backend_name/server_name changed its IP from 10.xx.xx.xx to 10.xx.xx.xx by name-dns/name-dns-01
I also often see this message even if the server hasn’t been reported as down:
Server backend_name/server_name administratively READY thanks to valid DNS answer.
DNS responses typically arrive in under 30ms.
show stat resolvers command does not show that any timeouts occurred:
sent: 10797 valid: 1034 update: 493 cname: 0 cname_error: 0 any_err: 869 nx: 0 timeout: 0 refused: 0 other: 0 invalid: 0 too_big: 0 truncated: 0 outdated: 260