HAProxy random HTTP 503 errors

Question

We\'ve setup 3 servers:

• Server A with Nginx + HAproxy to perform load balancing
• backend server B
• backend server C

Here is our

Answer 1

I had the same issue. After days of pulling my hair out I found the issue.

I had two HAProxy instances running. One was a zombie that somehow never got killed during maybe an update or a haproxy restart. I noticed this when refreshing the /haproxy stats page and the PID would change between two different numbers. The page with one of the numbers had absurd connection stats. To confirm I did

netstat -tulpn | grep 80

and saw two haproxy processes listening to port 80.

To fix the issue I did a "kill xxxx" where xxxx is the pid with the suspicious statistics.