How to configure nginx reverse proxy for apache with servername on different server

Question

I have server1 with public IP and server2 with local IP, I want to access my app hosted by apache on the server2 from server1 public IP using nginx reverse proxy. Here's my config.

Apache2 config

<VirtualHost *:80>
    ServerName ci_app.local
    DocumentRoot /var/www/ci_app/public
    <Directory /var/www/ci_app/public>
        Options Indexes FollowSymLinks MultiViews
        AllowOverride All
        Require all granted
    </Directory>
    ErrorLog /var/log/apache2/ACD_error.log
    CustomLog /var/log/apache2/ACD_requests.log combined
</VirtualHost>

Nginx config

server {
        listen 8000;
        server_name ci_app.local;

        port_in_redirect on;

        location / {
                proxy_set_header Host $host:$server_port;
                proxy_set_header X-Real-IP $remote_addr;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_set_header X-Forwarded-Proto $scheme;
                proxy_pass http://<server2_local_ip>:80/;
        }
}

Using that configuration I only get the default Apache virtualhost when accessing the http://<server1_public_ip>:8000.

I've tried changing the Nginx header config to

proxy_set_header Host ci_app.local

Which allow me to access the app but rather than server1 public IP the ajax sent the request to ci_app.local which unaccessible from outside the local.network.

So, how to correctly reverse proxy my app?

Answer 1

Just fixed this by manipulating the Header.

This maybe not a proper way for using the X-Forwarded-Host and Host header but it fixed the problem. Here's my config.

Nginx config

server {
        listen 8000;
        server_name ci_app.local;

        port_in_redirect on;

        location / {

                proxy_set_header X-Forwarded-Host $host:$server_port; #Set request host header and server port to X-Forwarded-Host header
                proxy_set_header Host ci_app.local; #Set target servername to Host Header

                proxy_set_header X-Real-IP $remote_addr;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_set_header X-Forwarded-Proto $scheme;
                proxy_pass http://<server2_local_ip>:80/;
        }
}

Apache2 config

<VirtualHost *:80>
    ServerName ci_app.local

    SetEnvIf X-Forwarded-Host (.*) proxy_host=$1 #Set the X-Forwarded_Host value to env
    RequestHeader set Host "%{proxy_host}e" #Replace the Host header to X-Forwarded_Host value which saved in env

    DocumentRoot /var/www/ci_app/public
    <Directory /var/www/ci_app/public>
        Options Indexes FollowSymLinks MultiViews
        AllowOverride All
        Require all granted
    </Directory>
    ErrorLog /var/log/apache2/ACD_error.log
    CustomLog /var/log/apache2/ACD_requests.log combined
</VirtualHost>

This config successfully redirect my request to server2 while fixed the wrong ajax request url.