Nginx and Lighttpd support 'set' and 'include' inside 'VirtualHost'. It's make simple switch from 'standard' to 'proxy' (let say nginx-proxy) without 're-create' whole web configs.
Imagine like this:
1. Config for certain domain:
VirtualHost {
set var_user = apache
Include /home/hiawatha/conf/globals/switch.conf
...
}
2. Config for fastcgi:
## taken 'var_user' from 'set'
UseFastCGI = php_for_var_user
UseToolkit = findindexfile
3. Config for proxy:
ReverseProxy !\.(pl|cgi|py|rb|shmtl) http://127.0.0.1:30080/ 90 keep-alive
UseToolkit = findindexfile, permalink
So, switch from fastcgi to proxy just copy of proxy content to /home/hiawatha/conf/globals/switch.conf and then restart. The same way for switch from proxy to hiawatha.