How To Configure Nginx as a Web Server and Reverse Proxy for Apache on One Ubuntu 18.04 Server

The author selected the Electronic Frontier Foundation to receive a donation as part of the Write for DOnations program.

Introduction #

Apache and Nginx are two popular open-source web servers often used with PHP. It can be useful to run both of them on the same virtual machine when hosting multiple websites which have varied requirements. The general solution for running two web servers on a single system is to either use multiple IP addresses or different port numbers.
Servers which have both IPv4 and IPv6 addresses can be configured to serve Apache sites on one protocol and Nginx sites on the other, but this isn’t currently practical, as IPv6 adoption by ISPs is still not widespread. Having a different port number like 81 or 8080 for the second web server is another solution, but sharing URLs with port numbers (such as http://example.com:81) isn’t always reasonable or ideal.
In this tutorial you’ll configure Nginx as both a web server and as a reverse proxy for Apache – all on a single server.
Depending on the web application, code changes might be required to keep Apache reverse-proxy-aware, especially when SSL sites are configured. To avoid this, you will install an Apache module called mod_rpaf which rewrites certain environment variables so it appears that Apache is directly handling requests from web clients.
We will host four domain names on one server. Two will be served by Nginx: example.com (the default virtual host) and sample.org. The remaining two, foobar.net and test.io, will be served by Apache. We’ll also configure Apache to serve PHP applications using PHP-FPM, which offers better performance over mod_php.

Prerequisites #

To complete this tutorial, you’ll need the following:

A new Ubuntu 18.04 server configured by following the Initial Server Setup with Ubuntu 18.04. This includes a sudo non-root user and a firewall.
Four fully-qualified domain names configured to point to your server’s IP address. See Step 3 of How To Set Up a Host Name with DigitalOcean for an example of how to do this. If you host your domains’ DNS elsewhere, you should create appropriate A records there instead.

Step 1 — Installing Apache and PHP-FPM #

Let’s start by installing Apache and PHP-FPM.
In addition to Apache and PHP-FPM, we will also install the PHP FastCGI Apache module, libapache2-mod-fastcgi, to support FastCGI web applications.
First, update your package list to ensure you have the latest packages.

sudo apt update

Next, install the Apache and PHP-FPM packages:

sudo apt install apache2 php-fpm

The FastCGI Apache module isn’t available in Ubuntu’s repository so download it from kernel.org and install it using the dpkg command.

wget https://mirrors.edge.kernel.org/ubuntu/pool/multiverse/liba/libapache-mod-fastcgi/libapache2-mod-fastcgi_2.4.7~0910052141-1.2_amd64.deb
sudo dpkg -i libapache2-mod-fastcgi_2.4.7~0910052141-1.2_amd64.deb

Next, let’s change Apache’s default configuration to use PHP-FPM.

Step 2 — Configuring Apache and PHP-FPM #

In this step we will change Apache’s port number to 8080 and configure it to work with PHP-FPM using the mod_fastcgi module. Rename Apache’s ports.conf configuration file:

sudo mv /etc/apache2/ports.conf /etc/apache2/ports.conf.default

Create a new ports.conf file with the port set to 8080:

echo "Listen 8080" | sudo tee /etc/apache2/ports.conf

Note: Web servers are generally set to listen on 127.0.0.1:8080 when configuring a reverse proxy but doing so would set the value of PHP’s environment variable SERVER_ADDR to the loopback IP address instead of the server’s public IP. Our aim is to set up Apache in such a way that its websites do not see a reverse proxy in front of it. So, we will configure it to listen on 8080 on all IP addresses.

Next we’ll create a virtual host file for Apache. The <VirtualHost> directive in this file will be set to serve sites only on port 8080.
Disable the default virtual host:

sudo a2dissite 000-default

Then create a new virtual host file, using the existing default site:

sudo cp /etc/apache2/sites-available/000-default.conf /etc/apache2/sites-available/001-default.conf

Now open the new configuration file:

sudo nano /etc/apache2/sites-available/001-default.conf

Change the listening port to 8080:
/etc/apache2/sites-available/000-default.conf

<VirtualHost *:8080>
    ServerAdmin webmaster@localhost
    DocumentRoot /var/www/html
    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>

Save the file and activate the new configuration file:

sudo a2ensite 001-default

Then reload Apache:

sudo systemctl reload apache2

Verify that Apache is now listening on 8080:

sudo netstat -tlpn

The output should look like the following example, with apache2 listening on 8080:

Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address     Foreign Address      State    PID/Program name
tcp        0      0 0.0.0.0:22        0.0.0.0:*            LISTEN   1086/sshd
tcp6       0      0 :::8080           :::*                 LISTEN   4678/apache2
tcp6       0      0 :::22             :::*                 LISTEN   1086/sshd

Once you verify that Apache is listening on the correct port, you can configure support for PHP and FastCGI.

Step 3 — Configuring Apache to Use mod_fastcgi #

Apache serves PHP pages using mod_php by default, but it requires additional configuration to work with PHP-FPM.

Note: If you are trying this tutorial on an existing installation of LAMP with mod_php, disable it first with sudo a2dismod php7.2.

We will be adding a configuration block for mod_fastcgi which depends on mod_action. mod_action is disabled by default, so we first need to enable it:

sudo a2enmod actions

Rename the existing FastCGI configuration file:

sudo mv /etc/apache2/mods-enabled/fastcgi.conf /etc/apache2/mods-enabled/fastcgi.conf.default

Create a new configuration file:

sudo nano /etc/apache2/mods-enabled/fastcgi.conf

Add the following directives to the file to pass requests for .php files to the PHP-FPM UNIX socket:
/etc/apache2/mods-enabled/fastcgi.conf

<IfModule mod_fastcgi.c>
  AddHandler fastcgi-script .fcgi
  FastCgiIpcDir /var/lib/apache2/fastcgi
  AddType application/x-httpd-fastphp .php
  Action application/x-httpd-fastphp /php-fcgi
  Alias /php-fcgi /usr/lib/cgi-bin/php-fcgi
  FastCgiExternalServer /usr/lib/cgi-bin/php-fcgi -socket /run/php/php7.2-fpm.sock -pass-header Authorization
  <Directory /usr/lib/cgi-bin>
    Require all granted
  </Directory>
</IfModule>

Save the changes and do a configuration test:

sudo apachectl -t

Reload Apache if Syntax OK is displayed:

sudo systemctl reload apache2

If you see the warning Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message., you can safely ignore it for now. We’ll configure server names later.
Now let’s make sure we can serve PHP from Apache.

Step 4 — Verifying PHP Functionality #

Let’s make sure that PHP works by creating a phpinfo() file and accessing it from a web browser.
Create the file /var/www/html/info.php which contains a call to the phpinfo function:

echo "<?php phpinfo(); ?>" | sudo tee /var/www/html/info.php

Note that if you followed the initial server setup in the Prerequisites sections, then you likely enabled the Apache firewall. Let’s go ahead and make sure that we can access our IP on port 8080, which is not currently accessible. We’ll restrict public access to this port in Step 10.
First allow port 8080 through the firewall:

sudo ufw allow 8080

Since we are going to secure our Apache domains, let’s go ahead and make sure TLS traffic on port 443 can enter.
Allow Apache Full to permit traffic on ports 80 and 443:

sudo ufw allow "Apache Full"

Now check your firewall status:

sudo ufw status

If you followed the prerequisites, then the output will look like this:

To                         Action      From
--                         ------      ----
OpenSSH                    ALLOW       Anywhere
Apache Full                ALLOW       Anywhere
8080                       ALLOW       Anywhere
OpenSSH (v6)               ALLOW       Anywhere (v6)
Apache Full (v6)           ALLOW       Anywhere (v6)
8080 (v6)                  ALLOW       Anywhere (v6)

You will see that port 8080 and Apache Full are allowed alongside any other firewall rules. Now let’s view our info.php page.
To see the file in a browser, go to http://your_server_ip:8080/info.php. This will give you a list of the configuration settings PHP is using.

At the top of the page, check that Server API says FPM/FastCGI. About two-thirds of the way down the page, the PHP Variables section will tell you the SERVER_SOFTWARE is Apache on Ubuntu. These confirm that mod_fastcgi is active and Apache is using PHP-FPM to process PHP files.

Step 5 — Creating Virtual Hosts for Apache #

Let’s create Apache virtual host files for the domains foobar.net and test.io. To do that, we’ll first create document root directories for both sites and place some default files in those directories so we can easily test our configuration.
First, create the document root directories:

sudo mkdir -v /var/www/foobar.net /var/www/test.io

Then create an index file for each site:

echo "<h1 style='color: green;'>Foo Bar</h1>" | sudo tee /var/www/foobar.net/index.html
echo "<h1 style='color: red;'>Test IO</h1>" | sudo tee /var/www/test.io/index.html

Then create a phpinfo() file for each site so we can test that PHP is configured properly.

echo "<?php phpinfo(); ?>" | sudo tee /var/www/foobar.net/info.php
echo "<?php phpinfo(); ?>" | sudo tee /var/www/test.io/info.php

Now create the virtual host file for the foobar.net domain:

sudo nano /etc/apache2/sites-available/foobar.net.conf

Add the following code to the file to define the host:
/etc/apache2/sites-available/foobar.net.conf

    <VirtualHost *:8080>
        ServerName foobar.net
        ServerAlias www.foobar.net
        DocumentRoot /var/www/foobar.net
        <Directory /var/www/foobar.net>
            AllowOverride All
        </Directory>
    </VirtualHost>

The line AllowOverride All enables .htaccess support.
These are only the most basic directives. For a complete guide on setting up virtual hosts in Apache, see How To Set Up Apache Virtual Hosts on Ubuntu 16.04.
Save and close the file. Then create a similar configuration for test.io. First create the file:

sudo nano /etc/apache2/sites-available/test.io.conf

Then add the configuration to the file:
/etc/apache2/sites-available/test.io.conf

    <VirtualHost *:8080>
        ServerName test.io
        ServerAlias www.test.io
        DocumentRoot /var/www/test.io
        <Directory /var/www/test.io>
            AllowOverride All
        </Directory>
    </VirtualHost>

Save the file and exit the editor.
Now that both Apache virtual hosts are set up, enable the sites using the a2ensite command. This creates a symbolic link to the virtual host file in the sites-enabled directory:

sudo a2ensite foobar.net
sudo a2ensite test.io

Check Apache for configuration errors again:

sudo apachectl -t

You’ll see Syntax OK displayed if there are no errors. If you see anything else, review the configuration and try again.
Reload Apache to apply the changes once your configuration is error-free:

sudo systemctl reload apache2

To confirm the sites are working, open http://foobar.net:8080 and http://test.io:8080 in your browser and verify that each site displays its index.html file.
You’ll see the following results:

Also, ensure that PHP is working by accessing the info.php files for each site. Visit http://foobar.net:8080/info.php and http://test.io:8080/info.php in your browser.
You’ll see the same PHP configuration spec list on each site as you saw in Step 4.
We now have two websites hosted on Apache at port 8080. Let’s configure Nginx next.

Step 6 — Installing and Configuring Nginx #

In this step we’ll install Nginx and configure the domains example.com and sample.org as Nginx’s virtual hosts. For a complete guide on setting up virtual hosts in Nginx, see How To Set Up Nginx Server Blocks (Virtual Hosts) on Ubuntu 18.04.
Install Nginx using the package manager:

sudo apt install nginx

Then remove the default virtual host’s symlink since we won’t be using it any more:

sudo rm /etc/nginx/sites-enabled/default

We’ll create our own default site later (example.com).
Now we’ll create virtual hosts for Nginx using the same procedure we used for Apache. First create document root directories for both the websites:

sudo mkdir -v /usr/share/nginx/example.com /usr/share/nginx/sample.org

We’ll keep the Nginx web sites in /usr/share/nginx, which is where Nginx wants them by default. You could put them under /var/www/html with the Apache sites, but this separation may help you associate sites with Nginx.
As you did with Apache’s virtual hosts, create index and phpinfo() files for testing after setup is complete:

echo "<h1 style='color: green;'>Example.com</h1>" | sudo tee /usr/share/nginx/example.com/index.html
echo "<h1 style='color: red;'>Sample.org</h1>" | sudo tee /usr/share/nginx/sample.org/index.html
echo "<?php phpinfo(); ?>" | sudo tee /usr/share/nginx/example.com/info.php
echo "<?php phpinfo(); ?>" | sudo tee /usr/share/nginx/sample.org/info.php

Now create a virtual host file for the domain example.com:

sudo nano /etc/nginx/sites-available/example.com

Nginx calls server {. . .} areas of a configuration file server blocks. Create a server block for the primary virtual host, example.com. The default_server configuration directive makes this the default virtual host which processes HTTP requests which do not match any other virtual host.
/etc/nginx/sites-available/example.com

server {
    listen 80 default_server;

    root /usr/share/nginx/example.com;
    index index.php index.html index.htm;

    server_name example.com www.example.com;
    location / {
        try_files $uri $uri/ /index.php;
    }

    location ~ .php$ {
        fastcgi_pass unix:/run/php/php7.2-fpm.sock;
        include snippets/fastcgi-php.conf;
    }
}

Save and close the file. Now create a virtual host file for Nginx’s second domain, sample.org:

sudo nano etc/nginx/sites-available/sample.org

Add the following to the file:
/etc/nginx/sites-available/sample.org

server {
    root /usr/share/nginx/sample.org;
    index index.php index.html index.htm;

    server_name sample.org www.sample.org;
    location / {
        try_files $uri $uri/ /index.php;
    }

    location ~ .php$ {
        fastcgi_pass unix:/run/php/php7.2-fpm.sock;
        include snippets/fastcgi-php.conf;
    }
}

Save and close the file.
Then enable both sites by creating symbolic links to the sites-enabled directory:

sudo ln -s /etc/nginx/sites-available/example.com /etc/nginx/sites-enabled/example.com
sudo ln -s /etc/nginx/sites-available/sample.org /etc/nginx/sites-enabled/sample.org

Then test the Nginx configuration to ensure there are no configuration issues:

sudo nginx -t

Then reload Nginx if there are no errors:

sudo systemctl reload nginx

Now access the phpinfo() file of your Nginx virtual hosts in a web browser by visiting http://example.com/info.php and http://sample.org/info.php. Look under the PHP Variables sections again.

[“SERVER_SOFTWARE”] should say nginx, indicating that the files were directly served by Nginx. [“DOCUMENT_ROOT”] should point to the directory you created earlier in this step for each Nginx site.
At this point, we have installed Nginx and created two virtual hosts. Next we will configure Nginx to proxy requests meant for domains hosted on Apache.

Step 7 — Configuring Nginx for Apache’s Virtual Hosts #

Let’s create an additional Nginx virtual host with multiple domain names in the server_name directives. Requests for these domain names will be proxied to Apache.
Create a new Nginx virtual host file to forward requests to Apache:

sudo nano /etc/nginx/sites-available/apache

Add the following code block which specifies the names of both Apache virtual host domains and proxies their requests to Apache. Remember to use the public IP address in proxy_pass:
/etc/nginx/sites-available/apache

server {
    listen 80;
    server_name foobar.net www.foobar.net test.io www.test.io;

    location / {
        proxy_pass http://your_server_ip:8080;
        proxy_set_header Host $host;
        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;
    }
}

Save the file and enable this new virtual host by creating a symbolic link:

sudo ln -s /etc/nginx/sites-available/apache /etc/nginx/sites-enabled/apache

Test the configuration to ensure there are no errors:

sudo nginx -t

If there are no errors, reload Nginx:

sudo systemctl reload nginx

Open the browser and access the URL http://foobar.net/info.php in your browser. Scroll down to the PHP Variables section and check the values displayed.

The variables SERVER_SOFTWARE and DOCUMENT_ROOT confirm that this request was handled by Apache. The variables HTTP_X_REAL_IP and HTTP_X_FORWARDED_FOR were added by Nginx and should show the public IP address of the computer you’re using to access the URL.
We have successfully set up Nginx to proxy requests for specific domains to Apache. Next, let’s configure Apache to set the REMOTE_ADDR variable as if it were handling these requests directly.

Step 8 — Installing and Configuring mod_rpaf #

In this step you’ll install an Apache module called mod_rpaf which rewrites the values of REMOTE_ADDR, HTTPS and HTTP_PORT based on the values provided by a reverse proxy. Without this module, some PHP applications would require code changes to work seamlessly from behind a proxy. This module is present in Ubuntu’s repository as libapache2-mod-rpaf but is outdated and doesn’t support certain configuration directives. Instead, we will install it from source.
Install the packages needed to build the module:

sudo apt install unzip build-essential apache2-dev

Download the latest stable release from GitHub:

wget https://github.com/gnif/mod_rpaf/archive/stable.zip

Extract the downloaded file:

unzip stable.zip

Change into the new directory containing the files:

cd mod_rpaf-stable

Compile and install the module:

make
sudo make install

Next, create a file in the mods-available directory which will load the rpaf module:

sudo nano /etc/apache2/mods-available/rpaf.load

Add the following code to the file to load the module:
/etc/apache2/mods-available/rpaf.load

LoadModule rpaf_module /usr/lib/apache2/modules/mod_rpaf.so

Save the file and exit the editor.
Create another file in this directory called rpaf.conf which will contain the configuration directives for mod_rpaf:

sudo nano /etc/apache2/mods-available/rpaf.conf

Add the following code block to configure mod_rpaf, making sure to specify the IP address of your server:
/etc/apache2/mods-available/rpaf.conf

    <IfModule mod_rpaf.c>
        RPAF_Enable             On
        RPAF_Header             X-Real-Ip
        RPAF_ProxyIPs           your_server_ip 
        RPAF_SetHostName        On
        RPAF_SetHTTPS           On
        RPAF_SetPort            On
    </IfModule>

Here’s a brief description of each directive. See the mod_rpaf README file for more information.

RPAF_Header – The header to use for the client’s real IP address.
RPAF_ProxyIPs – The proxy IP to adjust HTTP requests for.
RPAF_SetHostName – Updates the vhost name so ServerName and ServerAlias work.
RPAF_SetHTTPS – Sets the HTTPS environment variable based on the value contained in X-Forwarded-Proto.
RPAF_SetPort – Sets the SERVER_PORT environment variable. Useful for when Apache is behind a SSL proxy.

Save rpaf.conf and enable the module:

sudo a2enmod rpaf

This creates symbolic links of the files rpaf.load and rpaf.conf in the mods-enabled directory. Now do a configuration test:

sudo apachectl -t

Reload Apache if there are no errors:

sudo systemctl reload apache2

Access the phpinfo() pages http://foobar.net/info.php and http://test.io/info.php in your browser and check the PHP Variables section. The REMOTE_ADDR variable will now also be that of your local computer’s public IP address.
Now let’s set up TLS/SSL encryption for each site.

Step 9 — Setting Up HTTPS Websites with Let’s Encrypt (Optional) #

In this step we will configure TLS/SSL certificates for both the domains hosted on Apache. We’ll obtain the certificates through [Let’s Encrypt]( https://letsencrypt.org]. Nginx supports SSL termination so we can set up SSL without modifying Apache’s configuration files. The mod_rpaf module ensures the required environment variables are set on Apache to make applications work seamlessly behind a SSL reverse proxy.
First we will separate the server {...} blocks of both the domains so that each of them can have their own SSL certificates. Open the file /etc/nginx/sites-available/apache in your editor:

sudo nano /etc/nginx/sites-available/apache

Modify the file so that it looks like this, with foobar.net and test.io in their own server blocks:
/etc/nginx/sites-available/apache

    server {
        listen 80;
        server_name foobar.net www.foobar.net;
    
        location / {
            proxy_pass http://your_server_ip:8080;
            proxy_set_header Host $host;
            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;
        }
    }
    server {
        listen 80;
        server_name test.io www.test.io;
    
        location / {
            proxy_pass http://your_server_ip:8080;
            proxy_set_header Host $host;
            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;
        }
    }

We’ll use Certbot to generate our TLS/SSL certificates. Its Nginx plugin will take care of reconfiguring Nginx and reloading the config whenever necessary.
First, add the official Certbot repository:

sudo add-apt-repository ppa:certbot/certbot

Press ENTER when prompted to confirm you want to add the new repository. Then update the package list to pick up the new repository’s package information:

sudo apt update

Then install Certbot’s Nginx package with apt:

sudo apt install python-certbot-nginx

Once it’s installed, use the certbot command to generate the certificates for foobar.net and www.foobar.net:

sudo certbot --nginx -d foobar.net -d www.foobar.net

This command tells Certbot to use the nginx plugin, using -d to specify the names we’d like the certificate to be valid for.
If this is your first time running certbot, you will be prompted to enter an email address and agree to the terms of service. After doing so, certbot will communicate with the Let’s Encrypt server, then run a challenge to verify that you control the domain you’re requesting a certificate for.
Next, Certbot will ask how you’d like to configure your HTTPS settings:

Please choose whether or not to redirect HTTP traffic to HTTPS, removing HTTP access.
-------------------------------------------------------------------------------
1: No redirect - Make no further changes to the webserver configuration.
2: Redirect - Make all requests redirect to secure HTTPS access. Choose this for
new sites, or if you're confident your site works on HTTPS. You can undo this
change by editing your web server's configuration.
-------------------------------------------------------------------------------
Select the appropriate number [1-2] then [enter] (press 'c' to cancel):

Select your choice, then press ENTER. The configuration will be updated, and Nginx will reload to pick up the new settings.
Now execute the command for the second domain:

sudo certbot --nginx -d test.io -d www.test.io

Access one of Apache’s domains in your browser using the https:// prefix; visit https://foobar.net/info.php and you’ll see this:

Look in the PHP Variables section. The variable SERVER_PORT has been set to 443 and HTTPS set to on, as though Apache was directly accessed over HTTPS. With these variables set, PHP applications do not have to be specially configured to work behind a reverse proxy.
Now let’s disable direct access to Apache.

Step 10 — Blocking Direct Access to Apache (Optional) #

Since Apache is listening on port 8080 on the public IP address, it is accessible by everyone. It can be blocked by working the following IPtables command into your firewall rule set.

sudo iptables -I INPUT -p tcp --dport 8080 ! -s your_server_ip -j REJECT --reject-with tcp-reset

Be sure to use your server’s IP address in place of the example in red. Once port 8080 is blocked in your firewall, test that Apache is unreachable on it. Open your web browser and try accessing one of Apache’s domain names on port 8080. For example: http://example.com:8080
The browser should display an “Unable to connect” or “Webpage is not available” error message. With the IPtables tcp-reset option in place, an outsider would see no difference between port 8080 and a port that doesn’t have any service on it.

Note: IPtables rules do not survive a system reboot by default. There are multiple ways to preserve IPtables rules, but the easiest is to use iptables-persistent in Ubuntu’s repository. Explore this article to learn more about how to configure IPTables.

Now let’s configure Nginx to serve static files for the Apache sites.

Step 11 — Serving Static Files Using Nginx (Optional) #

When Nginx proxies requests for Apache’s domains, it sends every file request for that domain to Apache. Nginx is faster than Apache in serving static files like images, JavaScript and style sheets. So let’s configure Nginx’s apache virtual host file to directly serve static files but send PHP requests on to Apache.
Open the file /etc/nginx/sites-available/apache in your editor:

sudo nano /etc/nginx/sites-available/apache

You’ll need to add two additional location blocks to each server block, as well as modify the existing location sections. In addition, you’ll need to tell Nginx where to find the static files for each site.
If you’ve decided not to use SSL and TLS certificates, modify your file so it looks like this:
/etc/nginx/sites-available/apache

server {
    listen 80;
    server_name test.io www.test.io;
    root /var/www/test.io;
    index index.php index.htm index.html;

    location / {
        try_files $uri $uri/ /index.php;
    }

    location ~ .php$ {
        proxy_pass http://your_server_ip:8080;
        proxy_set_header Host $host;
        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;
    }

    location ~ /.ht {
        deny all;
    }
}

server {
    listen 80;
    server_name foobar.net www.foobar.net;
    root /var/www/foobar.net;
    index index.php index.htm index.html;

    location / {
        try_files $uri $uri/ /index.php;
    }

    location ~ .php$ {
        proxy_pass http://your_ip_address:8080;
        proxy_set_header Host $host;
        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;
    }

    location ~ /.ht {
        deny all;
    }
}

If you also want HTTPS to be available, use the following configuration instead:
/etc/nginx/sites-available/apache

server {
    listen 80;
    server_name test.io www.test.io;
    root /var/www/test.io;
    index index.php index.htm index.html;

    location / {
        try_files $uri $uri/ /index.php;
    }

    location ~ .php$ {
        proxy_pass http://your_server_ip:8080;
        proxy_set_header Host $host;
        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;
    }

    location ~ /.ht {
        deny all;
    }

    listen 443 ssl;
    ssl_certificate /etc/letsencrypt/live/test.io/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/test.io/privkey.pem;
    include /etc/letsencrypt/options-ssl-nginx.conf;
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem;
}

server {
    listen 80;
    server_name foobar.net www.foobar.net;
    root /var/www/foobar.net;
    index index.php index.htm index.html;

    location / {
        try_files $uri $uri/ /index.php;
    }

    location ~ .php$ {
        proxy_pass http://your_ip_address:8080;
        proxy_set_header Host $host;
        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;
    }

    location ~ /.ht {
        deny all;
    }

    listen 443 ssl;
    ssl_certificate /etc/letsencrypt/live/foobar.net/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/foobar.net/privkey.pem;
    include /etc/letsencrypt/options-ssl-nginx.conf;
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem;
}

The try_files directive makes Nginx look for files in the document root and directly serve them. If the file has a .php extension, the request is passed to Apache. Even if the file is not found in the document root, the request is passed on to Apache so that application features like permalinks work without problems.

Warning: The location ~ /.ht directive is very important; this prevents Nginx from serving the contents of Apache configuration files like .htaccess and .htpasswd which contain sensitive information.

Save the file and perform a configuration test:

sudo nginx -t

Reload Nginx if the test succeeds:

sudo service nginx reload

To verify things are working, you can examine Apache’s log files in /var/log/apache2 and see the GET requests for the info.php files of test.io and foobar.net. Use the tail command to see the last few lines of the file, and use the -f switch to watch the file for changes:

sudo tail -f /var/log/apache2/other_vhosts_access.log

Now visit http://test.io/info.php in your browser and then look at the output from the log. You’ll see that Apache is indeed replying:

    test.io:80 your_server_ip - - [01/Jul/2016:18:18:34 -0400] "GET /info.php HTTP/1.0" 200 20414 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/47.0.2526.111 Safari/537.36"

Then visit the index.html page for each site and you won’t see any log entries from Apache. Nginx is serving them.
When you’re done observing the log file, press CTRL+C to stop tailing it.
With this setup, Apache will not be able to restrict access to static files. Access control for static files would need to be configured in Nginx’s apache virtual host file, but that’s beyond the scope of this tutorial.

Conclusion #

You now have one Ubuntu server with Nginx serving example.com and sample.org, along with Apache serving foobar.net and test.io. Though Nginx is acting as a reverse-proxy for Apache, Nginx’s proxy service is transparent and connections to Apache’s domains appear be served directly from Apache itself. You can use this method to serve secure and static sites.