variable map for fastcgi_pass

[Sergey Kandaurov]

> On 25 Sep 2017, at 22:12, Kyle Sloan <kyle at ifsight.com> wrote:
> 
> Hello,
> 
> I am trying to use a MAP function based on HOSTNAMES to determine if this domain should fastcgi_pass to a php5 or php7 container, but am having problems.
> 
> My map looks like
>  
> map $host $php_proxy_container {
>   hostnames;
> 
>   default "php5fpm:9000";
> 
>   www.example.com    "php7fpm:9000";
> }
> 
> 
> My fastcgi file looks like
> 
>   fastcgi_pass   $php_proxy_container;
> 
> 
> [..]
> 
> I get a generic 502 bad gateway, and nothing more in the http log.  Changing the fastcgi_pass line to the exact value in the map and restarting does work.
> 

If variable used within fastcgi_pass evaluates to something like
hostname:port, you need to define resolver to resolve that name.
http://nginx.org/r/resolver

OTOH, if that name is used within fastcgi_pass literally,
it would be resolved at startup by system resolver instead.

-- 
Sergey Kandaurov