Getting 502 instead of 503 when all backend servers are down running HAProxy behind Apache
- by scarba05
I'm testing running HAProxy as a dedicated load balancer behind Apache 2.2, replacing our current configuration where we use Apache's load balancer. In our current, Apache only, set-up if all the backend (origin) servers are down Apache will serve a 503 service unavailable message. With HAProxy I get a 502 bad gateway response.
I'm using a simple reverse proxy rewrite rule in Apache
RewriteRule ^/(.*) http://127.0.0.1:8000/$1 [last,proxy]
In HAProxy I have the following (running in default tcp mode)
defaults
log global
option tcp-smart-accept
timeout connect 7s
timeout client 60s
timeout queue 120s
timeout server 60s
listen my_server 127.0.0.1:8000
balance leastconn
server backend1 127.0.0.1:8001 check observe layer4 maxconn 2
server backend1 127.0.0.1:8001 check observe layer4 maxconn 2
Testing connecting directly to the load balancer when the backend servers are down:
[root@dev ~]# wget http://127.0.0.1:8000/ test.html
--2012-05-28 11:45:28-- http://127.0.0.1:8000/
Connecting to 127.0.0.1:8000... connected.
HTTP request sent, awaiting response... No data received.
So presumably this is down to the fact that HAProxy accepts the connection and then closes it.
