Aegir supports multiple 'server' entities. These servers have 'services' such as 'Web' or 'Database', and 'service types' which are implementations of that service, such as 'Apache' or 'MySQL'.

Remote web servers

System dependencies

On the remote server, install these packages

Aegir user

Any number of remote web servers may be configured. The remote server needs an aegir user created on the system.

Web server configuration

You'll also need to prepare the web server in the same way you did for the master Aegir server during installation:

Don't restart Apache even when it prompts you. This will be done by the Verify task you'll spawn for the server from the Aegir frontend later.

Sudoers

Add the aegir user to sudoers so it can restart Apache.

Login shell

The remote aegir user will also need a login shell, which can be modified using the chsh command.

SSH keys

SSH public/private keys should be set up so the main Aegir server's aegir user can access remote web aegir users with no passwords required.

Example: on main Aegir server:

Do not use a passphrase when you create your key. Simply press Enter to leave the passphrase blank. Otherwise, SSH will insist that you enter the passphrase everytime you try to SSH using the key. We don't want SSH to present any prompts.

Put the public key's contents into /var/aegir/.ssh/authorized_keys on the remote web server. The easiest way to do this is to use the ssh-copy-id command.

You should manually login for the first time from your Aegir master server to your remote server as the aegir user, so that the remote web server is added to the known_hosts file in /var/aegir/.ssh on your Aegir master server. Verifying the remote webserver will fail until this has been done.

There are many, many tutorials online for setting up ssh keys, and various mistakes can be made by inexperienced users such as permissions etc. Aegir isn't a 'Linux beginner's practice tool', so setting these up is really out of the scope of this document and users are encouraged to research this on their own. (For Ubuntu, see this article).

If you have followed the instructions above, and your SSH connection gets closed immediately after you try to connect to the remote server as the aegir user, you may not have given the aegir user a shell correctly. Check the /etc/passwd file on the remote server to make sure that the aegir user has a shell.

Verify the server

Now you can add a new server node in Aegir, set the hostname and/or IP and set the service type to be 'Apache' (or Apache_SSL if this site is to handle SSL sites).

A verify task will be spawned and added to the Task queue ready for dispatching. During a server verification task, various configurations will be set on the Aegir master server and also synced to the remote web server, restarting Apache.

Now when you add a new Platform node in Aegir, you have the option of setting which web server to host it on. If you are not using a makefile but are downloading a platform manually, you must still do this on the main Aegir server. The contents will then be synced across to the web server.

You don't choose a web server when installing a new site. Because a site depends on a platform, its web server is implied by which platform has been chosen. In other words, all sites on a platform are hosted on the same server. You cannot host two sites on the same platform on different servers.