Installing and Uninstalling System Packages

It is important to make sure that by installing and uninstalling system
packages the extension does not break Plesk’s normal functioning.

Handling unsupported operating systems

The extension must check whether the OS it is being installed on is
supported or not. If it is not, the extension must clearly communicate
it to the user in an error message. Naturally, in this case, the
extension must not be installed.

Here is the list of operating systems currently supported by Plesk:
Supported operating
systems.

Installing packages

When implementing the process of installing extension’s packages, take
into consideration the following guidelines.

1. Show a clear warning to the user that packages will be installed with
   the extension, which will alter the current state of the system. The
   user must be explicitly made aware of the changes. Optionally, the
   installed packages may be listed for the user’s convenience.
2. Before installing, the extension must check whether the packages it
   requires are already installed or not. If they are, they must not be
   installed again.
3. Check that the packages and dependencies to be installed are not
   conflicting with packages already installed on the system. If such
   conflicts exist, the user must be explicitly informed of this fact.
4. Make sure that all the necessary packages and package repositories
   are installed.
5. Make sure that all the dependencies and corresponding repositories
   are installed.
6. Make sure there are no errors reported in panel.log

Testing tips:

1. New packages and repositories must be available to install on all
   operating systems and versions of Plesk supported by the extension.
2. Installing the packages does not break any of the related Plesk
   functionality.
3. Make sure there are no errors reported in panel.log

Use long tasks to install packages

The process of installation takes considerable time. Plesk provides the
mechanism of long tasks exactly for the situations like
this.

Uninstalling extensions or packages through extension

1. Ideally, the system should be reverted back to the state prior to the
   extension installation.
2. All packages, dependencies and repositories installed by the
   extension must be removed at uninstall.
3. System packages installed before the extension packages must not be
   removed.
4. Plesk repositories must remain available and present on the
   repositories list.
5. Plesk must work.
6. Make sure there are no errors reported in panel.log