HAProxy community

Server is going DOWN for maintenance (DNS timeout status)


#1

Hi all,

Sometimes (about 5 times this month), I have the following errors in the haproxy logs and I don’t really understand why:

Server XXXXX is going DOWN for maintenance (DNS timeout status). 0 active and 0 backup servers left. 0 sessions active, 0 requeued, 0 remaining in queue.
Server XXXXX administratively READY thanks to valid DNS answer.
Server XXXXX ('XXXXXXX') is UP/READY (resolves again).

The HA Proxy version is 1.7.9 and I use the nbproc parameter in the configuration.

I know there is a bug about this parameter and the DNS resolution (DNS Resolution *Sigh* v1.7.1) but it seems to be resolved in the 1.7.3 (https://www.haproxy.org/download/1.7/src/CHANGELOG).

The HA Proxy servers use AWS DNS to resolve the backend name.

Thanks for your help,


#2

There are no known DNS bugs in haproxy 1.7.9.

This simply means that based on the configured timeouts, none of the DNS servers could be reached. Capture your DNS traffic long term if you want to confirm this.


#3

Thanks for your reply :grinning: !

How do you suggest to monitor DNS traffic ?

I am also thinking to add hold valid 30s into the resolvers section.


#4

Capture it with tcpdump into a file.

tcpdump -nps0 -w all-dns-traffic.cap port 53

Once you had the issue, stop the capture and look at it in Wireshark.