Ansible 2.8.7 API 使用异常3：官网例子无输出

[官网API](https://docs.ansible.com/ansible/2.8/dev_guide/developing_api.html#python-api)

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    #!/usr/bin/env python
    
    import json
    import shutil
    from ansible.module_utils.common.collections import ImmutableDict
    from ansible.parsing.dataloader import DataLoader
    from ansible.vars.manager import VariableManager
    from ansible.inventory.manager import InventoryManager
    from ansible.playbook.play import Play
    from ansible.executor.task_queue_manager import TaskQueueManager
    from ansible.plugins.callback import CallbackBase
    from ansible import context
    import ansible.constants as C
    
    class ResultCallback(CallbackBase):
        """A sample callback plugin used for performing an action as results come in
    
        If you want to collect all results into a single object for processing at
        the end of the execution, look into utilizing the ``json`` callback plugin
        or writing your own custom callback plugin
        """
        def v2_runner_on_ok(self, result, **kwargs):
            """Print a json representation of the result
    
            This method could store the result in an instance attribute for retrieval later
            """
            host = result._host
            print(json.dumps({host.name: result._result}, indent=4))
    
    # since the API is constructed for CLI it expects certain options to always be set in the context object
    context.CLIARGS = ImmutableDict(connection='local', module_path=['/to/mymodules'], #注意指定路径 or 删掉 or None

                                    forks=10, become=None,
                                    become_method=None, become_user=None, check=False, diff=False)
    
    # initialize needed objects
    loader = DataLoader() # Takes care of finding and reading yaml, json and ini files
    passwords = dict(vault_pass='secret')  #注意密码, 本机执行可忽略
    
    # Instantiate our ResultCallback for handling results as they come in. Ansible expects this to be one of its main display outlets
    results_callback = ResultCallback()
    
    # create inventory, use path to host config file as source or hosts in a comma separated string
    inventory = InventoryManager(loader=loader, sources='localhost')  #注意没逗号 or ['localhost'] or ['localhost',]
    
    # variable manager takes care of merging all the different sources to give you a unified view of variables available in each context
    variable_manager = VariableManager(loader=loader, inventory=inventory)
    
    # create data structure that represents our play, including tasks, this is basically what our YAML loader does internally.
    play_source =  dict(
            name = "Ansible Play",
            hosts = 'localhost',
            gather_facts = 'no',
            tasks = [
                dict(action=dict(module='shell', args='ls'), register='shell_out'),
                dict(action=dict(module='debug', args=dict(msg='{{shell_out.stdout}}')))
             ]
        )
    
    # Create play object, playbook objects use .load instead of init or new methods,
    # this will also automatically create the task objects from the info provided in play_source
    play = Play().load(play_source, variable_manager=variable_manager, loader=loader)
    
    # Run it - instantiate task queue manager, which takes care of forking and setting up all objects to iterate over host list and tasks
    tqm = None
    try:
        tqm = TaskQueueManager(
                  inventory=inventory,
                  variable_manager=variable_manager,
                  loader=loader,
                  passwords=passwords,
                  stdout_callback=results_callback,  # Use our custom callback instead of the ``default`` callback plugin, which prints to stdout
              )
        result = tqm.run(play) # most interesting data for a play is actually sent to the callback's methods
    finally:
        # we always need to cleanup child procs and the structures we use to communicate with them
        if tqm is not None:
            tqm.cleanup()
    
        # Remove ansible tmpdir
        shutil.rmtree(C.DEFAULT_LOCAL_TMP, True)