Apache 2 Web Server on Ubuntu 10.10 (Maverick)

http://library.linode.com/web-servers/apache/installation/ubuntu-10.10-maverick

Apache 2 Web Server on Ubuntu 10.10 (Maverick)

Published: Monday, December 6th, 2010 by
Sam Kleinman
This tutorial explains how to install and configure the Apache webserver on Ubuntu 10.10 (Maverick). All configuration will be done through theterminal; make sure you are logged in as root via SSH.If you have not followed thegetting
startedguide, it is recommended that you do so prior to beginning this guide.Also note that if you're looking to install a full LAMP stack,you may want to consider using our

LAMP guide for Ubuntu 10.10.

Contents

Set the Hostname
Install Apache 2
Install Support for Scripting

Configure Name-based Virtual Hosts

Install Apache Modules
Configuration Options
Multi-Processing Module
More Information

Set the Hostname

Before you begin installing and configuring the components described in this guide, please makesure you've followed our instructions forsetting your hostname.Issue
the following commands to make sure it is set properly:

hostname
hostname -f

The first command should show your short hostname, and the second should show yourfully qualified domain name (FQDN).

Install Apache 2

Make sure your package repositories and installed programs are up todate by issuing the following commands:

apt-get update
apt-get upgrade

Enter the following command to install the Apache HTTP server, itsdocumentation, and a collection of utilities.

apt-get install apache2 apache2-doc apache2-utils

Install Support for Scripting

The following commands are optional, and should be run if you want tohave support within Apache for server-side scripting in PHP, Ruby,Python, or Perl.

To install Ruby support, issue the following command:

apt-get install libapache2-mod-ruby

To install Perl support, issue the following command:

apt-get install libapache2-mod-perl2

To install Python support, issue the following command:

apt-get install libapache2-mod-python

If you need support for MySQL in Python, you will also need to installPython MySQL support:

apt-get install python-mysqldb

Your PHP application may require additional dependencies included in Ubuntu.To check for available PHP dependencies run "apt-cache search php", whichwill provide a list of package names and descriptions.
To install, issue thefollowing command:

apt-get install libapache2-mod-php5 php5 php-pear php5-xcache

Issue the following command to install the php5-suhosin package, whichprovides additional security to your PHP installation:

apt-get install php5-suhosin

If you're also hoping to run PHP with MySQL, then also install MySQLsupport:

apt-get install php5-mysql

Configure Name-based Virtual Hosts

There are different ways to set up Virtual Hosts, however we recommend themethod below. By default, Apache listens on all IP addresses available to it.

First, issue the following command to disable the default Apachevirtual host.

a2dissite default

Each additional virtual host needs its own file in the/etc/apache2/sites-available/ directory. In this example, you'llcreate files for twoname-based virtually hosted sites,"example.net"
and "example.org".

First create bucknell.net (/etc/apache2/sites-available/example.net) sothat it resembles the following.

File:/etc/apache2/sites-available/bucknell.net

<VirtualHost *:80>
ServerAdmin admin@example.net
ServerName example.net
ServerAlias www.example.net
DocumentRoot /srv/www/example.net/public_html/
ErrorLog /srv/www/example.net/logs/error.log
CustomLog /srv/www/example.net/logs/access.log combined
</VirtualHost>

If you would like to enable Perl support, then add the followinglines to the
VirtualHost entry above.

File excerpt:/etc/apache2/sites-available/example.net

Options ExecCGI
AddHandler cgi-script .pl

Next, create example.org (/etc/apache2/sites-available/example.org) sothat it resembles this:

File:/etc/apache2/sites-available/ducklington.org

<VirtualHost *:80>
ServerAdmin webmaster@example.org
ServerName example.org
ServerAlias www.example.org
DocumentRoot /srv/www/example.org/public_html/
ErrorLog /srv/www/example.org/logs/error.log
CustomLog /srv/www/example.org/logs/access.log combined
</VirtualHost>

You'll note that some basic options are specified for both sites,including where the files for the site will reside (under/srv/www/). You can add (or remove) additional configurationoptions, such as the Perl support, on
a site-by-site basis to thesefiles as your needs dictate.

Create required directories for these sites by issuing the following commands:

mkdir -p /srv/www/example.net/public_html
mkdir /srv/www/example.net/logs

mkdir -p /srv/www/example.org/public_html
mkdir /srv/www/example.org/logs

Enable the sites by issuing these commands:

a2ensite example.net
a2ensite example.org

Finally, restart the Apache server to initialize all the changes,with this command:

/etc/init.d/apache2 restart

When you create or edit any virtual host file, you'll need to reload theconfig, which you can do without restarting the server with thefollowing command:

/etc/init.d/apache2 reload

Congratulations! You now have Apache installed on your Ubuntu LinuxVPS and have configured the server for virtual hosting.

Install Apache Modules

One of Apache's prime strengths is its extreme customizability andflexibility. With its support for a large number of modules,there are few web serving tasks that Apache cannot fulfill. By default,modules and their configuration files are installed in the/etc/apache2/mods-available/
directory. Generating a list of thisdirectory will tell you what modules are installed. To enable a modulelisted in this directory, use the following command:

a2enmod [module-name]

Note that in the /etc/apache2/mods-available/ directory, files have a.load and.conf extension. Module names do not include theextension.

To disable a module that is currently enabled, use the inversecommand:

a2dismod [module-name]

To get a list of available Apache modules modules in the Ubuntu repositoryuse the following command:

apt-cache search libapache2*

To install one of these modules use the command:

apt-get install [module-name]

Modules should be enabled and ready to use following installation, thoughyou may have to apply additional configuration options to have accessto the modules' functionality. Consult theApache
module documentationfor more information regarding the configuration of specific modules.

Configuration Options

One of the strengths, and obstacles, of Apache is the immense amount offlexibility offered in its configuration files. In the defaultinstallation of Apache 2 on Ubuntu, the main configuration islocated in the/etc/apache2/apache2.conf
files, but Apacheconfiguration directives are loaded from files in a number of differentlocations, in a specific order. Configuration files are read in thefollowing order, with items specified later taking precedence overearlier and potentially conflicting
options:

/etc/apache2/apache2.conf
Files with .load or
.conf extensions in/etc/apache2/mods-enabled/ directory.
/etc/apache2/httpd.conf (Blank by default.)
/etc/apache2/ports.conf
Files within the /etc/apache2/conf.d/ directory.
Files within the /etc/apache2/sites-enabled/ directory.
Per-directory .htaccess files in the directory.

Remember, later files take precedence over earlier-cited files. Withina directory of included configuration files, files will be read inorder based on the sort of their file names.

Apache will follow symbolic links to read configuration files, soyou can create links in these directories and locations to files thatare actually located elsewhere in your file system.

Best practices for most installations dictate that we don't recommendmodifying the following default configuration files:/etc/apache2/httpd.conf, files in/etc/apache2/mods-enabled/,and
in most cases/etc/apache2/apache2.conf. This is to avoidunnecessary confusion and unintended conflicts in the future.

Generally, as specified in the
LAMP guideand elsewhere, files that configure virtual hosts should be located in the/etc/apache2/sites-available/ directory (and symbolically linked tosites-enabled/
with the a2ensite tool. This allows for a clearand specific per-site configuration.

In practice, the vast majority of configuration options will probablybe located in site-specific virtual host configuration files.If you need to set a system-wide configuration option or aren't using virtualhosting, the best practice is to specify options
in files createdbeneath the conf.d/ directory.

Multi-Processing Module

The default Apache configuration uses a tool called MPM-worker. Thismulti-processing module can handle a large number of requests quicklyby utilizing multiple threads per worker process. However, this use ofmultiple threads is not compatible with some PHP
extensions. When PHPis installed MPM-worker is replaced with MPM-prefork, which allowsApache to handle requests without threading for greater compatibilitywith some software. Furthermore, using MPM-prefork allows Apache toisolate requests in separate processes
so that if one request failsfor some reason, other requests will be unaffected.

For more complex setups, however, we recommend that you consider usingan alternate MPM module called "ITK".mpm-itk is quite similar toprefork, but it goes one step
further and runs the processes for each siteunder a distinct user account. This is particularly useful insituations where you're hosting a number of distinct sites that youneed to isolate sites on the basis of user privileges.

Begin by installing the mpm-itk module:

apt-get install apache2-mpm-itk

Now, in the <VirtualHost > entries for your sites (thesite-specific files in/etc/apache2/sites-available/) add thefollowing sub-block:

File excerpt:Apache Virtual Host Configuration

<IfModule mpm_itk_module>
AssignUserId webeditor webgroup
</IfModule>

In this example, webeditor is the name of the user of the specificsite in question, andwebgroup is the name of the particular groupthat "owns" the web server related files and processes.
Remember thatyou must create the user accounts and groups using theuseraddcommand.

More Information

You may wish to consult the following resources for additionalinformation on this topic. While these are provided in the hope that they willbe useful, please note that we cannot vouch for the accuracy or timeliness ofexternally hosted materials.

Apache HTTP Server Version 2.2 Documentation
Apache Configuration