7429a7073d
We need to do this if we can to keep the contract that show/list always print JSON. This allows us to print human readable messages and not break scripts that depend on stdout being JSON.
84 lines
2.0 KiB
Python
84 lines
2.0 KiB
Python
from __future__ import print_function
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import abc
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import collections
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import json
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import sys
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from dcos.api import errors, util
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try:
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basestring = basestring
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except NameError:
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# We are in python3 define basestring as str
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basestring = str
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logger = util.get_logger(__name__)
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class Emitter(object):
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"""Abstract class for emitting events."""
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@abc.abstractmethod
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def publish(self, event):
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"""Publishes an event.
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:param event: event to publish
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:type event: any
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"""
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raise NotImplementedError
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class FlatEmitter(Emitter):
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"""Simple emitter that sends all publish events to the provided handler.
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If no handler is provider then use :py:const:`DEFAULT_HANDLER`.
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:param handler: event handler to call when publish is called
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:type handler: func(event) where event is defined in
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:py:func:`FlatEmitter.publish`
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"""
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def __init__(self, handler=None):
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if handler is None:
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self._handler = DEFAULT_HANDLER
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else:
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self._handler = handler
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def publish(self, event):
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"""Publishes an event.
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:param event: event to publish
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:type event: any
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"""
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self._handler(event)
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def print_handler(event):
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"""Default handler for printing event to stdout.
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:param event: event to emit to stdout
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:type event: str, dict or dcos.api.errors.Error
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"""
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if event is None:
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# Do nothing
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pass
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elif isinstance(event, basestring):
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print(event)
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elif isinstance(event, collections.Mapping) or isinstance(event, list):
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json.dump(event, sys.stdout, sort_keys=True, indent=2)
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print('')
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elif isinstance(event, errors.Error):
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print(event.error(), file=sys.stderr)
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else:
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logger.error(
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'Unable to print event. Type not supported: %s, %r.',
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type(event),
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event)
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DEFAULT_HANDLER = print_handler
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"""The default handler for an emitter: :py:func:`print_handler`."""
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