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Viewing changes to src/provisioningserver/utils/introspect.py

  • Committer: MAAS Lander
  • Author(s): Gavin Panella
  • Date: 2015-04-24 17:47:07 UTC
  • mfrom: (3759.4.18 introspect-service)
  • Revision ID: maas_lander-20150424174707-9eqa8y0bedjz0vm2
[r=rbanffy][bug=][author=allenap] Allow interactive introspection of running MAAS daemons.

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src/provisioningserver/utils/introspect.py
 
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# Copyright 2014 Canonical Ltd.  This software is licensed under the
 
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# GNU Affero General Public License version 3 (see the file LICENSE).
 
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"""Twisted Application Plugin code for the MAAS Region."""
 
5
 
 
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from __future__ import (
 
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    absolute_import,
 
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    print_function,
 
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    unicode_literals,
 
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    )
 
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str = None
 
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__metaclass__ = type
 
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__all__ = [
 
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    "IntrospectionShellService",
 
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    "serverFromString",
 
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]
 
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from twisted.application.internet import StreamServerEndpointService
 
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from twisted.conch import manhole
 
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from twisted.conch.insults import insults
 
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from twisted.internet import (
 
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    endpoints,
 
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    reactor,
 
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)
 
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from twisted.internet.interfaces import IProtocolFactory
 
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from zope.interface import implementer
 
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def byteString(thing):
 
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    """Convert `string` to a byte string."""
 
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    if isinstance(thing, bytes):
 
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        return thing
 
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    elif isinstance(thing, unicode):
 
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        return thing.encode("utf-8")
 
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    else:
 
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        raise TypeError(
 
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            "Cannot safely convert %r to a byte string."
 
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            % (thing,))
 
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def serverFromString(description):
 
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    """Parse `description` into an endpoint.
 
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    Twisted's `endpoints.serverFromString` raises errors that are not
 
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    particularly user-friendly, so we attempt something better here.
 
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    """
 
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    description = byteString(description)
 
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    try:
 
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        return endpoints.serverFromString(reactor, description)
 
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    except ValueError:
 
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        raise ValueError(
 
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            "Could not understand server description %r. "
 
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            "Try something like %r or %r." % (
 
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                description, b"unix:/path/to/file:mode=660:lockfile=0",
 
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                b"tcp:1234:interface=127.0.0.1"))
 
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class Help(object):
 
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    """Define the builtin 'help'.
 
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    This is a wrapper around pydoc.help... with a twist, in that it disallows
 
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    interactive use.
 
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    """
 
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    def __repr__(self):
 
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        message = "Type help(object) for help about object."
 
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        return message.encode("utf-8")
 
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    def __call__(self, *args, **kwds):
 
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        if len(args) == 0:
 
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            message = "Interactive help has been disabled. %r" % self
 
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            print(message.encode("utf-8"))
 
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        else:
 
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            from pydoc import help
 
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            return help(*args, **kwds)
 
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class IntrospectionShell(manhole.ColoredManhole):
 
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    STYLE_BRIGHT_ON = '\x1b[1m'
 
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    STYLE_OFF = '\x1b[0m'
 
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    COLOUR_RED_ON = '\x1b[31m'
 
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    COLOUR_MAGENTA_ON = '\x1b[35m'
 
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    COLOUR_OFF = '\x1b[39m'
 
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    def __init__(self, namespace=None):
 
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        super(IntrospectionShell, self).__init__(namespace)
 
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        self.ensureThereIsHelp()
 
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    def ensureThereIsHelp(self):
 
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        if self.namespace is None:
 
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            self.namespace = {"help": Help()}
 
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        elif "help" in self.namespace:
 
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            pass  # Don't override.
 
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        else:
 
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            self.namespace["help"] = Help()
 
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    def welcomeMessage(self):
 
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        return "".join((
 
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            self.STYLE_BRIGHT_ON,
 
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            self.COLOUR_MAGENTA_ON,
 
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            "Welcome to MAAS's Introspection Shell.",
 
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            self.COLOUR_OFF,
 
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            self.STYLE_OFF,
 
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            "\n\n",
 
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            self.STYLE_BRIGHT_ON,
 
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            "This is the ",
 
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            self.COLOUR_RED_ON,
 
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            self.factory.location.upper(),
 
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            self.COLOUR_OFF,
 
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            ".",
 
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            self.STYLE_OFF,
 
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        ))
 
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    def initializeScreen(self):
 
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        """Override in order to provide welcome message."""
 
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        self.terminal.reset()
 
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        self.addOutput(b"\n")
 
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        self.addOutput(self.welcomeMessage().encode("utf-8"))
 
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        self.addOutput(b"\n")
 
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        self.addOutput(b"\n")
 
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        self.setInsertMode()
 
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        self.drawInputLine()
 
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@implementer(IProtocolFactory)
 
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class IntrospectionShellFactory:
 
131
 
 
132
    def __init__(self, location, namespace):
 
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        super(IntrospectionShellFactory, self).__init__()
 
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        self.namespace = namespace
 
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        self.location = location
 
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    def buildProtocol(self, addr):
 
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        proto = insults.ServerProtocol(
 
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            IntrospectionShell, self.namespace)
 
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        proto.factory = self
 
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        return proto
 
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143
    def doStart(self):
 
144
        """See `IProtocolFactory`."""
 
145
 
 
146
    def doStop(self):
 
147
        """See `IProtocolFactory`."""
 
148
 
 
149
 
 
150
class IntrospectionShellService(StreamServerEndpointService):
 
151
 
 
152
    def __init__(self, location, endpoint, namespace):
 
153
        factory = IntrospectionShellFactory(location, namespace=namespace)
 
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        super(IntrospectionShellService, self).__init__(endpoint, factory)