Plugins

Aptdaemon provides a plugin mechanism by making use of setuptools’ entry points. The group name is aptdaemon.plugins.

Cache modifiers

Currently there are two types of plugins available which allow you to modify the marked changes of a transaction. Each plugin can be a function which accepts the resolver (apt.cache.ProblemResolver) and the cache (apt.cache.Cache) as arguments:

• modify_cache_before The plugged-in function is called after the intentional changes of the transaction have been marked, but before the dependencies have been resolved.
• modify_cache_after The plugged-in function is called after the dependency resolution of the transaction. The resolver will be called again afterwards.

A short overview of the steps required to process a transaction:

1. Mark intentional changes (e.g. the to be installed packages of a InstallPackages transaction)
2. Call all modify_cache_before plugins
3. Run the dependency resolver
4. Call all modify_cache_after_plugins and re-run the resolver
5. Commit changes

External helpers

There is also the get_license_key plugin which allows to retrieve the license key content and path to store. License keys are required by propriatary software. The plugged-in function gets called with uid of the user who started the transaction, the package name, a JSON OAuth tocken and the name of a server to query.

Example

Here is an example which would install language packages ./plugins/aptd.py:

>>> def install_language_packs(resolver, cache):
>>>     """Marks the required language packs for installation."""
>>>     #... do the magic here ...
>>>     language_pack.mark_install(False, True)
>>>     # Only protect your changes if they are mantadory. If they cannot be
>>>     # be installed the transaction will fail.
>>>     resolver.clear(language_pack)
>>>     resolver.protect(language_pack)

Finally you would have to register your function as entry point in setup.py:

>>> setup(
>>> ...
>>> entry_points="""[aptdaemon.plugins]
>>> modify_cache_after=plugins.aptd:install_language_packs
>>> """,
>>> ...
>>> )

Note

Keep in mind that you can only register one entry point per name/plugin per distribution.