Working with rewrite module in apache vhost file

I want to setup my vhost file, that when a folder is accessed, it opens, executes and serves back to the browser the out put of default.cgi

I can get that working, no problem, but I want it also setup so that if the client tries to access any file on the server directly, including default.cgi, it must serve back the document /404.cgi

Here is a copy of my current vhost file that happily serves default.cgi... but when I tried enable one of the rules that I have commented out, then everything I do just returns Error 500.

Code:

<VirtualHost *:80>
    ServerName api.mydomain.tld

    DocumentRoot /home/api/endpoints

    <Directory "/home/api/endpoints">
        Options +ExecCGI
        AddHandler cgi-script .cgi
        AllowOverride All

        RewriteEngine On
        RewriteBase /

        # Serve default.cgi for any folder access
        RewriteCond %{REQUEST_FILENAME} -d
        RewriteRule ^(.*)/?$ $1/default.cgi [L]

#        RewriteCond %{REQUEST_FILENAME} !-d
#        RewriteRule ^(.*)/?$ /404.cgi [L]

#        # Catch-all rule for any other requests not matching previous conditions
#        RewriteRule ^(.*)$ /404.cgi [L]

        Require all granted
    </Directory>

    # Custom error document (optional, if you want to specify a 404 error page)
    ErrorDocument 404 /404.cgi

    # Log locations
    ErrorLog /home/api/log/apache_error.log
    CustomLog /home/api/log/apache_access.log combined
</VirtualHost>

 

From a blank error.log, it generates a massive file from one http request.

I think it is hitting a race condition.

So I am now trying to research how to rather have a folder structure that is void of files, but when you got / or /endpoint or whatever, then it executes the file default.cgi from an external location. Say, /home/api/code/default.cgi or /home/api/code/endpoint/default.cgi