Plugin Interface

DNF plugin can be any Python class fulfilling the following criteria:

1. it derives from dnf.Plugin,
2. it is made available in a Python module stored in one of the Conf.pluginpath,
3. provides its own name and __init__().

When DNF CLI runs it loads the plugins found in the paths during the CLI’s initialization.

class dnf.Plugin

The base class all DNF plugins must derive from.

name

The plugin must set this class variable to a string identifying the plugin. The string can only contain alphanumeric characters and underscores.

static read_config(conf)

Read plugin’s configuration into a ConfigParser compatible instance. conf is a Conf instance used to look up the plugin configuration directory.

__init__(base, cli)

The plugin must override this. Called immediately after all the plugins are loaded. base is an instance of dnf.Base. cli is an instance of dnf.cli.Cli but can also be None in case DNF is running without a CLI (e.g. from an extension).

pre_config()

This hook is called before configuring the repos.

config()

This hook is called immediately after the CLI/extension is finished configuring DNF. The plugin can use this to tweak the global configuration or the repository configuration.

resolved()

This hook is called immediately after the CLI has finished resolving a transaction. The plugin can use this to inspect the resolved but not yet executed Base.transaction.

sack()

This hook is called immediately after Base.sack is initialized with data from all the enabled repos.

pre_transaction()

This hook is called just before transaction execution. This means after a successful transaction test. RPMDB is locked during that time.

transaction()

This hook is called immediately after a successful transaction. Plugins that were removed or obsoleted by the transaction will not run the transaction hook.

register_command(command_class)

A class decorator for automatic command registration.

Example of a plugin that provides a hello-world dnf command (the file must be placed in one of the pluginpath directories:

import dnf

@dnf.plugin.register_command
class HelloWorldCommand(dnf.cli.Command):
    aliases = ('hello-world',)
    summary = 'The example command'

    def run(self):
        print('Hello world!')

To run the command:

$ dnf hello-world
Hello world!

You may want to see the comparison with yum plugin hook API.