If you’re a server admin, you probably have a web server of your choice like Apache, or Nginx. Apache is a well-known web server since the 1990s. Nginx was first developed in 2004 and quickly gained traction due to its lightweight memory footprint and fast processing speed for static HTML files.

Both Apache and Nginx support virtual hosting, which means you can host multiple websites or web applications on the same server. However, you will encounter situations in which you have an existing web server running, but a particular web application requires using a different web server. Port 80 or 443 on the public IP address can be used by only one process. If Apache is using the port, then Nginx can’t use (or bind to) it. So what can you do?

You can configure Nginx as a reverse proxy to Apache, so Nginx can redirect HTTP requests to Apache. In my experience, I found that this isn’t always the best way because it has once caused weird problems that I cannot troubleshoot. Instead, I prefer to use HAProxy as a reverse proxy for both Nginx and Apache. HAProxy is a free, open-source high availability load balancer and proxy server for TCP and HTTP-based applications.

Run Apache, Nginx and HAProxy on the Same Server

Here’s how it works.

  • Nginx listens on 127.0.0.1:80 and 127.0.0.1:443
  • Apache listens on 127.0.0.2:80 and 127.0.0.2:443
  • HAPorxy listens on port 80 and 443 of the public IP address. It redirects HTTP request on port 80 to port 443. When a request arrives on port 443, it will choose between Nginx and Apache back end by analyzing the SNI (server name indication) header in the HTTPS request.

Step 1: Stop Nginx and Apache

To stop Nginx on Debian, Ubuntu and CentOS, run

sudo systemctl stop nginx

To stop Apache on Debian/Ubuntu, run

sudo systemctl stop apache2

To stop Apache on CentOS, run

sudo systemctl stop httpd

Step 2: Change the Listen Port in Nginx

We need to make Nginx listen on 127.0.0.1:80. Open your Nginx configuration files in /etc/nginx/conf.d/ or /etc/nginx/sites-enabled/ and find the following line.

listen 80;

Change it to

listen 127.0.0.1:80;

If https is enabled on the Nginx server block, then also find

listen 443 ssl;

And change it to

listen 127.0.0.1:443 ssl;

The Nginx main configuration file /etc/nginx/nginx.conf might include a default virtual host listening on port 80 or 443, so you might need to edit this file too.

Restart Nginx for the changes to take effect.

sudo systemctl restart nginx

Step 3: Change the Listen Port in Apache

We need to make Apache listen on 127.0.0.2:80.

Debian/Ubuntu

On Debian and Ubuntu, edit the /etc/apache2/ports.conf file.

sudo nano /etc/apache2/ports.conf

Change

Listen 80
Listen 443

To

Listen 127.0.0.2:80
Listen 127.0.0.2:443

Save and close the file. Also go to /etc/apache2/sites-enabled/ directory, edit the virtual host files. Change



To




If there are SSL virtual host, then also change




To




Restart Apache.


sudo systemctl restart apache2


CentOS


On CentOS, edit the /etc/httpd/conf/httpd.conf file.


sudo nano /etc/httpd/conf/httpd.conf


Find


Listen 80


Change it to


Listen 127.0.0.2:80


Save and close the file. Then go to /etc/httpd/conf.d/ directory, edit the virtual host files. Change




To




If there are SSL virtual host, then also change




To




In the /etc/httpd/conf.d/ssl.conf file, there’s


Listen 443 https


Change it to:


Listen 127.0.0.2:443 https


Save and close the file. Restart Apache for the changes to take effect.


sudo systemctl restart httpd


Step 4: Configure HAProxy


Install HAProxy on your distro.


Debian/Ubuntu


sudo apt install haproxy


CentOS


sudo dnf install haproxy


Edit HAProxy configuration file.


sudo nano /etc/haproxy/haproxy.cfg


Add the following code snippet at the end of the file, which will make HAPorxy listen on port 80 of the public IP address and redirect HTTP requests on port 80 to port 443. Replace 12.34.56.78 with your server’s public IP address.


frontend http
    bind 12.34.56.78:80
    mode http
    redirect scheme https code 301


Now we also need to add an HTTPS front end.


frontend https
    bind 12.34.56.78:443
    mode tcp
    tcp-request inspect-delay 5s
    tcp-request content accept if { req_ssl_hello_type 1 }


Then define the Nginx and Apache back ends.


backend nginx
    mode tcp
    option ssl-hello-chk
    server nginx 127.0.0.1:443 check

backend apache
    mode tcp
    option ssl-hello-chk
    server apache 127.0.0.2:443 check


You can define a default back end with:


default_backend nginx


We will use SNI header in the HTTPS request to redirect to the correct back end. For example, if Nginx is serving domain1.com and Apache is serving domain2.com, then you add the following two lines.


use_backend nginx if { req_ssl_sni -i domain1.com }
use_backend apache if { req_ssl_sni -i domain2.com }



Note that the default_backend and use_backend directives should be placed above the backend definitions.


In the configuration above, we utilized the SNI (Server Name Indication) feature in TLS to differentiate HTTPS traffic.


    

  • When domain1.com is in the TLS Client Hello, HAProxy redirect traffic to the nginx backend.
    • 

  • When domain2.com is in the TLS Client Hello, HAProxy redirect traffic to the apache backend.
    • 



If the client doesn’t specify the server name in TLS Client Hello, then HAproxy will use the default backend (nginx).


Save and close the file. Then restart HAproxy.


sudo systemctl restart haproxy


Now Apache, Nginx and HAProxy are able to run on the same server.


How to Forward Client’s IP address to Backend


By default, Apache and Nginx can only see HAProxy’s IP address. To get client’s real IP address, make sure you added the send-proxy-v2 option in the HAProxy’s back end definition like below.


server nginx 127.0.0.1:443 send-proxy-v2 check

server apache 127.0.0.2:443 send-proxy-v2 check


We also need to add some configuration in Nginx and Apache.


Nginx


Add proxy_protocol in the Nginx listen directive like below.


listen 127.0.0.2:443 ssl http2 proxy_protocol;


Then add the following two directives in the Nginx http { } block.


set_real_ip_from 127.0.0.1;
real_ip_header proxy_protocol;


Save and close the file. Then reload Nginx.


sudo systemctl reload nginx


Apache


If you use Apache on Debian/Ubuntu, you need to enable the remoteip module. (This module is enabled on CentOS by default.)


sudo a2enmod remoteip


Then add the following directive in your Apache virtual host configuration file.


RemoteIPProxyProtocol On


Like this.


<VirtualHost 127.0.0.2:443>
    ServerName www.example.com
    RemoteIPProxyProtocol On


Then restart Apache for the changes to take effect.


sudo systemctl restart apache2


or


sudo systemctl restart httpd


Note that the RemoteIPProxyProtocol On directive is only available in Apache 2.4.31 and newer. To check your Apache version, run


sudo apache2 -v


or


sudo httpd -v


Ubuntu 18.04 ships with Apache 2.4.29. If your Apache version doesn’t meet this requirement, then you should remove the send-proxy-v2 in the HAProxy back end definition. CentOS 8 ships with Apache 2.4.37.


Finally, restart HAProxy.


sudo systemctl restart haproxy


Obtaining New Let’s Encrypt SSL Certificate


To obtain new Let’s Encrypt certificate for a new server block, I found I can only use the dns-01 challenge type. http-01 and tls-alpn-01 challenge won’t work.


Note that Certbot on CentOS 8 doesn’t have any DNS plugin. You can use acme.sh instead.


First, you need install Certbot DNS plugin. They are several DNS plugins available in the Debian and Ubuntu software repository, which you can find with


apt search python3-certbot-dns


Output:


python3-certbot-dns-cloudflare/bionic,bionic 0.23.0-1 all
Cloudflare DNS plugin for Certbot

python3-certbot-dns-digitalocean/bionic,bionic 0.23.0-1 all
DigitalOcean DNS plugin for Certbot

python3-certbot-dns-dnsimple/bionic,bionic 0.23.0-1 all
DNSimple DNS plugin for Certbot

python3-certbot-dns-google/bionic,bionic 0.23.0-1 all
Google DNS plugin for Certbot

python3-certbot-dns-rfc2136/bionic,bionic 0.23.0-1 all
RFC 2136 DNS plugin for Certbot

python3-certbot-dns-route53/bionic,bionic 0.23.0-1 all
Route53 DNS plugin for Certbot


Install one of these plugin according to which DNS hosting service you are using. I’m using Cloudflare, so I will use Cloudflare as an example. Run the following command to install the python3-certbot-dns-cloudflare package.


sudo apt install python3-certbot-dns-cloudflare


Then create a configuration file for Cloudflare.


sudo nano /etc/letsencrypt/cloudflare.ini


We need to add our Cloudflare account email address and API key in this file.


# Cloudflare API credentials used by Certbot
dns_cloudflare_email = [email protected]
dns_cloudflare_api_key = 0123456789abcdef0123456789abcdef01234567


You can find your Cloudflare API key at https://dash.cloudflare.com/profile. Note that the Certbot Cloudflare plugin does not currently support Cloudflare’s “API Tokens”, so ensure you use the “Global API Key” for authentication.


Save and close the file. The API key bypasses two factor authentication of Cloudflare, so you should only allow root user to read this file.


sudo chmod 600 /etc/letsencrypt/cloudflare.ini


Now run certbot.


sudo certbot --agree-tos -a dns-cloudflare -i nginx --redirect --hsts --staple-ocsp --email [email protected] -d www.your-domain.com,your-domain.com


In the above command, we specified that we will use dns-cloudflare as the authenticator to obtain new TLS certificate and use the nginx plugin to create the HTTPS server block. If you use Apache, then replace nginx with apache.


This command will ask you to enter the path of the .ini file, so enter /etc/letsencrypt/cloudflare.ini and press the Enter key.


After the SSL certificate is obtained and installed in the web server configuration file. You need to make it listen on 127.0.0.1:443 or 127.0.0.2:443. For example, if you use Nginx, then find


listen 443 ssl


And change it to


listen 127.0.0.1:443 ssl http2


Also change port 80 to


listen 127.0.0.1:80;


Save and close the file. Then restart your web server.


Common Errors


If you have multiple Nginx virtual hosts on a server, and when you type one domain name, the web browser takes you to another domain name hosted on the same server, it could be that your Nginx virtual host file name doesn’t end with the .conf file name extension, so Nginx didn’t load this virtual host.


Wrapping Up


I hope this tutorial helped you run Apache, Nginx and HAProxy on the same server. As always, if you found this post useful, then subscribe to our free newsletter to get more tips and tricks. Take care 🙂






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