Nginx -> Apache 2 authentication -> return to Nginix - authentication

Question

We have a nginx and an apache2 server.
Apache2 is configured to manage Kerberos (Active Directory) authentication.
We have a website managed by nginx with a reserved area.
I would know if this is possible:
the user goes to main site managed by nginx
from main site, there is a link to "/login" mapped to apache2:
location /login/ {
proxy_pass http://apache2server/testlogin;
}
when the login is successful, apache2 is configured to go to another nginx webpage, using proxypass too:
ProxyPass /testlogin http://nginxserver/logindone.php
ProxyPassReverse /testlogin http://nginxserver/logindone.php
I wonder if this is the right solution to the problem.

Answer 1

The best way you can implement an external authentication to your NGiNX website is using auth_request directive.
Basically, you can protect any request doing a subrequest to any external web server. The subrequest must return HTTP code 2XX to allow proceeding to the content, and any other HTTP code returned will deny access.
To accomplish that, be sure you've NGiNX with auth_request enabled (compiled with --with-http_auth_request_module). To check that, use the following command at shell:
nginx -V 2>&1 | grep "http_auth_request_module"
Add the auth_request directive to the location you want to protect, specifying an internal location where the authorization subrequest will be forwarded to, using:
location /system/ {
auth_request /auth;
#...
}
So, when a request is made to /system/ location, the system will create a subrequest to /auth location. Now we need to create the internal /auth location. We can use the following example below:
location = /auth {
internal;
proxy_pass http://my.app.webserver/auth_endpoint;
proxy_pass_request_body off;
proxy_set_header Content-Length "";
#...
}
Here, we created the /auth internal location. We used the internal directive to disable external NGiNX access (any external request to /auth will not be processed by this location). Also, we removed the request body content and set the request length to zero, removing any original request variable. We do a subrequest to http://my.app.webserver/auth_endpoint passing all requested cookies, so your backend application could determine if user has access or not.
If you need to know the original requested URI, you can add it on an extra HTTP header at subrequest adding:
proxy_set_header X-Original-URI $request_uri;
You can learn more about NGiNX auth_request directive here.