Aegir requires some special permissions to your server in order to automate some configurations. For example, when a new site is installed, the web server will be automatically configured (vhost) and restarted. Therefore Aegir cannot be installed on a shared hosting environment. Consult the system requirements to ensure you meet the necessary requirements.
Automatic or manual install?
The automatic install process through Debian packages is the currently recommended install process on Debian and Ubuntu platforms. It should just be a matter of adding the right sources to your APT repositories and running
apt-get install aegir.
The manual install process should take about 15 minutes for trained system administrators, between 30 to 60 minutes for others. The section contains detailed instructions on how to install Aegir manually on supported systems. It is aimed at system administrators and porters that want to control every step of the install process.
To decide which method is the right one, you may also want to review the operating system support page.
We also provide a troubleshooting guide to resolve common installation problems.
Note that, while installing Aegir does change some system configurations, it does only minor changes and keeps all its system configurations in one place so that it is easy to uninstall. It will not remove existing configurations. However, make sure you have backups before installing.
Automatic install and maintenance with Puppet
There is now a Aegir Puppet module that can further automate installation and maintenance of Aegir servers. It defaults to using the Debian packages, and is thus best-suited to Debian and it's derivatives (Ubuntu, Mepis, &.), but also supports (experimental) installation via the manual install process. This currently also only works on Debian, as it follows the documented installation procedure; however, it should be pretty straight-forward to adapt it to other OSes.
Development installs with Vagrant and Aegir-up
If you're installing Aegir for experimental or development purposes, you might be interested in Aegir-up, a Virtualbox/Vagrant-based local virtual machine automation system. It provides a simple method of building a complete Aegir system locally using the Puppet modules, and is, in fact, the primary development platform for them. In addition, you can build a dev version of Aegir from the git repos (with .git directories intact) to make debugging and writing patches and extensions easier.