How to install mod_proxy and setup reverse proxy in Apache Ubuntu

Today in this tutorial we will learn about installing apache proxy module and how to setup reverse proxy.
The module name is mod_proxy ,it is core module which supports Forward and Reverse Proxy settings in Apache WebServer. There are other modules also which is required in Apache webserver as per the requirement for example
mod_proxy_http, mod_proxy_ftp, mod_proxy_ajp, mod_proxy_balancer, and mod_proxy_connect

Reverse proxy is widely used to access the webserver which is behind the firewall.Reverse Proxy has the capability to load balance the request among the backend-server as well caching can also be done.Mainly, reverse proxies can be used simply to bring several servers into the same URL space.

For eg. lets see this scenario –

Scenario 1:
We have One Web server which has public ip address and DNS record means it can be accessible by using the url www.example.com or http://example.com
We have some internal webserver lets assume, internalwebserver1,internalwebserver2 and internalwebserver3. Internal web servers can not be access directly from public internet because they have private IP as well as they are behind the firewall. Means if someone try to access these internal server it will get error No such host.
But there are some important web application or webpages are serving from internal web server which is required to map with example.com .
So in this case what we will do we will setup the Reverse Proxy server. If any request come to main URL i.e example.com the Web Server will check which path is mapped to its internal web server in configuration file.

OK have this another Scenarios –

Scenario 2:
I have one OpenERP server which runs in port no. 8069 eg. http://openrp.example.com:8069 but I would like to open the website openerp.example.com in URL means port no. 80 bydefault. In this case also we can setup reverse proxy in single openerp server.

Install mod_proxy and setup reverse proxy in Apache Webserver

Follow the given below steps.
Note: In all given below example replace the value of ServerAdmin,ServerName & ServerAlias as per your server information

Step 1: Install the module

sudo apt-get install libapache2-mod-proxy-html

Step 2: Installing the dependency libxml2-dev

apt-get install libxml2-dev

Step 3: Load the module

a2enmod proxy proxy_http

Step 4: Create the Virtual Host in apache configuration file . If your configuration is located in conf.d you have to do changes in that file. I am giving example with default setting in Apache Webserver in Ubuntu

vi /etc/apache2/sites-enabled/000-default

Paste the below two lines within VirtualHost tag

ProxyPass /foo http://internalwebserver1.example.com/give/path/of-requested-location
ProxyPassReverse /foo http://internalwebserver1.example.com/give/path/of-requested-location

Lets see the configuration of my file,it will clear the doubt

        ServerAdmin sharad@example.com
        ServerName example.com
        ServerAlias example.com
       ProxyPass /foo http://internalwebserver1.example.com/files/webapp
       ProxyPassReverse /foo  http://internalwebserver1.example.com/files/webapp
    

Step 5: Now restart the apache

/etc/init.d/apache2 restart

Step 6: Now Openbrowser in client machine and check the website. Done

Now for Scenario 2:

Follow the all above given steps except in Step 4 you have to do below given setting
Below is the reference of my configuration file

        ServerAdmin sharad@example.com
        ServerName openerp.example.com
        ServerAlias openerp.example.com
       ProxyPass / http://openerp.example.com:8069
       ProxyPassReverse / http://openerp.example.com:8069
    

Restart the apache2 and open the browser and check it

/etc/init.d/apache2 restart