Python pkg_resources模块动态加载插件实例分析

module_path = 'your_project/demo'
module = import_module(module_path)
module.test()

#settings.py
MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
     ...
]
# 动态加载调用处代码
for middleware_path in reversed(settings.MIDDLEWARE):
    middleware = import_string(middleware_path)
    ...

...
def status_handler(runner_config, data):
    plugin_config = get_configuration(runner_config)
    if plugin_config['runner_url'] is not None:
        status = send_request(plugin_config['runner_url'],
                              data=data,
                              headers=plugin_config['runner_headers'],
                              urlpath=plugin_config['runner_path'])
        logger.debug("POST Response {}".format(status))
    else:
        logger.info("HTTP Plugin Skipped")
def event_handler(runner_config, data):
    status_handler(runner_config, data)

from .events import status_handler, event_handler # noqa

from setuptools import setup, find_packages
with open('README.md', 'r') as f:
    long_description = f.read()
setup(
    name="ansible-runner-http",
    version="1.0.0",
    author="Red Hat Ansible",
    url="https://github.com/ansible/ansible-runner-http",
    license='Apache',
    packages=find_packages(),
    long_description=long_description,
    long_description_content_type='text/markdown',
    install_requires=[
        'requests',
        'requests-unixsocket',
    ],
    #方式一：具体到某个module
    entry_points={'ansible_runner.plugins': ['http = ansible_runner_http']},
    #方式二：具体到某个module下的函数
    #entry_points={'ansible_runner.plugins': [
    #    'status_handler = ansible_runner_http:status_handler',
    #    'event_handler = ansible_runner_http:event_handler',
    #    ]
    #},
    zip_safe=False,
)

...
plugins = {
    #调用load方法，获取指向python的对象
    entry_point.name: entry_point.load()
    for entry_point
    #调用WorkingSet.iter_entry_points方法遍历所有EntryPoint,参数为组名
    in pkg_resources.iter_entry_points('ansible_runner.plugins')
}
...
def event_callback(self, event_data):
        '''
        Invoked for every Ansible event to collect stdout with the event data and store it for
        later use
        '''
    for plugin in plugins:
        plugins[plugin].event_handler(self.config, event_data)
        ...