Running a secondary PHP app from a subdirectory in Nginx - php

Question

I have a site built on the Kirby flat file CMS and its running in the root directory just fine, but I'm trying to get an instance of FlightPHP running in a subdirectory (called crm) of the above project. This FlightPHP instance will handle form submissions so I need to be able to map the urls correctly.
With Apache and .htaccess, it's easy:
# make forms/crm links work
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^crm/(.*) crm/index.php [L]
I just can't seem to get this working with Nginx, here's what I have so far:
server {
listen 80;
listen [::]:80;
root /var/www/mainsite;
index index.php index.html index.htm;
server_name mydomain.com;
autoindex on;
access_log off;
# Kirby Specific Directories
rewrite ^/site/(.*) /error permanent;
rewrite ^/kirby/(.*) /error permanent;
add_header X-UA-Compatible "IE=Edge,chrome=1";
location ~ .php {
fastcgi_pass unix:/var/run/php5-fpm.sock;
fastcgi_index index.php;
include fastcgi_params;
fastcgi_hide_header X-Powered-By;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
fastcgi_param PATH_INFO $fastcgi_script_name;
fastcgi_buffer_size 128k;
fastcgi_buffers 256 16k;
fastcgi_busy_buffers_size 256k;
fastcgi_temp_file_write_size 256k;
include fastcgi_params;
}
location ^~ /crm {
root /var/www/mainsite/crm;
if (!-e $request_filename)
{
rewrite ^/(.*)$ /index.php/$1 last;
break;
}
}
location / {
try_files $uri $uri/ /index.php?$query_string;
}
location ~* .(?:xml|ogg|mp3|mp4|ogv|svg|svgz|eot|otf|woff|ttf|css|js|jpg|jpeg|gif|png|ico)$ {
try_files $uri =404;
expires max;
access_log off;
log_not_found off;
add_header Pragma public;
add_header Cache-Control "public, must-revalidate, proxy-revalidate";
}
}
I have tried quite a few approaches from similar posts online, but none that work correctly.

Answer 1

Try replacing your location ^~ /crm block with this
location /crm {
try_files $uri $uri/ /crm/index.php?$args;
}
And if that one doesn't solve it try
location /crm {
try_files $uri $uri/ /crm/index.php?$uri;
}