Building Apache HTTPD Load Balancer from trunk on Ubuntu 11.10

This post discusses how to install Apache Module mod_proxy_balancer locally.
However, you can just configure mod_proxy load balancer using the builds, without using the source.
Downloading the sources
Download the HTTPD source and extract it
http://httpd.apache.org/download.cgi#apache24

Download APR, APR-Util, and pcre
http://apr.apache.org/download.cgi
ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/pcre-8.30.zip


Unpacking
Unpack APR and APR-Util into ./srclib/apr and ./srclib/apr-util
Be sure the domain names do not have version numbers; for example, the APR distribution must be under ./srclib/apr/
Extract pcre as well.

Building pcre
Go to pcre root directory
sudo ./configure --enable-unicode-properties
make
sudo make install

Configure HTTPD Load Balancer
Go to the httpd root folder.

./configure --with-included-apr --enable-proxy --enable-proxy-balancer
make
sudo make install

Now you have installed the Apache HTTPD Load Balancer locally, to its default location $APACHE2_HOME - /usr/local/apache2/. You can configure it to balance the load across your service instances that to be load balanced.

Configuring Apache mod_proxy load balancer

Installing Apache2 Server
-------------------

sudo apt-get install apache2
sudo /etc/init.d/apache2 restart

Setting up HTTPS
-----------------

sudo a2enmod ssl
sudo a2ensite default-ssl

Setting up load balancing modules
----------------------------------

sudo a2enmod proxy_balancer
sudo a2enmod proxy_http

Now enable mod_proxy in Apache, and proxy requests to the application server by adding the example below to your Apache httpd.conf

# Put this after the other LoadModule directives
LoadModule proxy_module /usr/lib/apache2/modules/mod_proxy.so
LoadModule proxy_http_module /usr/lib/apache2/modules/mod_proxy_http.so

cd /etc/apache2/mods-available
sudo vim proxy.conf 

        # set ProxyRequests off since we're only using the ProxyPass and ProxyPassReverse
        # directives. this keeps the server secure from
        # spammers trying to use your proxy to send email.

        ProxyRequests Off

        
                AddDefaultCharset off
                Order deny,allow
                Allow from all
                #Allow from .example.com
        

        # Enable/disable the handling of HTTP/1.1 "Via:" headers.
        # ("Full" adds the server version; "Block" removes all outgoing Via: headers)
        # Set to one of: Off | On | Full | Block

        ProxyVia On

# Put this in the main section of your configuration (or desired virtual host, if using Apache virtual hosts)
ProxyRequests Off
ProxyPreserveHost On


    Order deny,allow
    Allow from all

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

cd /usr/local/apache2/conf

Add the below line to httpd.conf

Include conf/extra/httpd-proxy-balancer.conf

Restart and reload the server
------------------------------------------------

sudo service apache2 restart
sudo service apache2 reload