Using HttpMapModule with proxy_pass got 502

Server NGINX
1

Hi everyone,

My project needs to route http request to different host with different
domain name. I deployed HttpMapModule and proxy_pass, and the related
nginx.conf segment is following:

http {
map $http_host $backend_servers {
app.example.com localdomain1; #if changed to ip, it’s ok
default localdomain2;
}

server {
listen 80;
server_name localhost;
location /{
proxy_pass http://$backend_servers;
}
…
}

When I send the requet uri as http://app.example.com, the result is 502
error. But if I changed the maping value as IP address not domain name,
it
worked with no problem. And if I change the proxy_pass item directly to
http://localdomain1, it also worked as normal.

Does the proxy_pass + http_map_module not refer to DNS look? or is there
any
other point wrong in the nginx.conf ?

Thanks for any suggestion.

Posted at Nginx Forum:

2

Hello!

On Wed, Jan 23, 2013 at 06:16:52AM -0500, amozz wrote:

}
When I send the requet uri as http://app.example.com, the result is 502
error. But if I changed the maping value as IP address not domain name, it
worked with no problem. And if I change the proxy_pass item directly to
http://localdomain1, it also worked as normal.

Does the proxy_pass + http_map_module not refer to DNS look? or is there any
other point wrong in the nginx.conf ?

Thanks for any suggestion.

For dynamic name resolution of upstream servers to work, you have
to configure resolver, see Module ngx_http_core_module.

You may also start looking into error log if something goes wrong.
In this case it should have “no resolver defined” errors logged.

–
Maxim D.

3

Thank you Maxim.

I added the resolver, and it works now!

Posted at Nginx Forum: