NGINX handling $_GET query parameters differently to Apache - apache

Question

I'm currently migrating a website from an Apache build that contains the following .htaccess rules:
<ifmodule mod_rewrite.c>
RewriteEngine on
RewriteBase /
RewriteRule ^$ index.php [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond $1 !^(index\.php|admin|captcha|print|pdf\.php|robots\.txt)
RewriteRule (.*) index.php?req=$1 [QSA,L]
</ifmodule>
I've setup NGINX and added the following location block:
location / {
try_files $uri /index.php?req=$uri$is_args$args;
}
This works for most pages, but some internal pages that handle query string are failing. After some debugging, I found that dumping $_GET was returning differently. The Apache server is returning:
array(2) { ["req"]=> string(8) "checkout" ["quick"]=> string(23) "email#address.com" }
which works perfectly for this old website, but the NGINX server is returning:
array(1) { ["req"]=> string(39) "/checkout?quick=email#address.com" }
Can anybody help me understand what's going on? It seems there's an issue with me passing req, as well as additional query params.
Update: I've managed to partly resolve this with the following NGINX settings, but it's annoying I have to manually exclude every path I don't want to be rewritten:
location / {
try_files $uri $uri/ /index.php?$is_args$args;
rewrite ^/(.*)$ /index.php?req=$1 last;
}
location /admin {
try_files $uri $uri/ /admin/index.php?$is_args$args;
}
location /js/ {
# Do nothing. nginx will serve files as usual.
}
location /css/ {
# Do nothing. nginx will serve files as usual.
}
location /images/ {
# Do nothing. nginx will serve files as usual.
}

Answer 1

I managed to resolve my issue with the following:
location / {
try_files $uri $uri/ /index.php?$is_args$args;
if (!-e $request_filename) {
rewrite ^/(.*)$ /index.php?req=$1 last;
}
}
which should prevent rewriting of non-request filenames.