plugin-development.md

Plugin development

This is an important step to enjoy all flexibility and features that this framework provides.

Steps

1. In the broker.cfg file add the plugin to the list of desired plugins:

Example:

[general]
plugins = plugin1,plugin2,my_new_plugin

[my_new_plugin]
var1 = 
var2 = 
var3 = 

In this tutorial, we will use MyNewPlugin as the plugin name

2. Create a new if statement condition in the file broker/service/api/init.py that will recognize if the new plugin added is informed in the configuration file (broker.cfg). If this condition is true, then the necessary variables to execute the plugin needs to be informed in the broker.cfg file and computed in the broker/service/api/init.py.

Example:

import ConfigParser

try:

[...]

if 'my_new_plugin' in plugins:
    var1 = config.get('my_new_plugin', 'var1')
    var2 = config.get('my_new_plugin', 'var2')
    var3 = config.get('my_new_plugin', 'var3')

[...]

3. Create a new folder under broker/plugins with the desired plugin name and add init.py.

4. Write a new python class under broker/plugins/mynewplugin

It must implement the methods get_title, get_description, to_dict and execute.

• get_title(self)

  • Returns plugin title

• get_description(self)

  • Returns plugin description

• to_dict(self)

  • Return a dict with the plugin information, name, title and description

• execute(self, data)

  • Actually execute the logic of cluster creation and job execution
  • Returns information if the execution was successful or not

Example:

from broker.plugins import base

class MyNewPluginProvider(base.PluginInterface):

    def get_title(self):
        return 'My New Plugin'

    def get_description(self):
        return 'My New Plugin'

    def to_dict(self):
        return {
            'name': self.name,
            'title': self.get_title(),
            'description': self.get_description(),
        }

    def execute(self, data):
        return True

5. Add the new plugin to setup.py under entry_points:

    entry_points={
        'console_scripts': [
            'broker=broker.cli.main:main',
        ],
        'broker.execution.plugins': [
            'my_new_plugin=broker.plugins.my_new_plugin.plugin:MyNewPluginProvider',
        ],

Note: Make sure that the name matches under setup.py and the broker.cfg otherwise the plugin won’t be loaded.