218 lines
6.8 KiB
Python
218 lines
6.8 KiB
Python
# Copyright 2015 Canonical Ltd.
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# This file is part of cloud-init. See LICENCE file for license information.
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#
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# vi: ts=4 expandtab
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import abc
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import itertools
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import six
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from cloudinit import exceptions
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from cloudinit import logging
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from cloudinit import sources
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from cloudinit.sources import strategy
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LOG = logging.getLogger(__name__)
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class APIResponse(object):
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"""Holds API response content
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To access the content in the binary format, use the
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`buffer` attribute, while the unicode content can be
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accessed by calling `str` over this (or by accessing
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the `decoded_buffer` property).
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"""
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def __init__(self, buffer, encoding="utf-8"):
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self.buffer = buffer
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self.encoding = encoding
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self._decoded_buffer = None
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@property
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def decoded_buffer(self):
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# Avoid computing this again and again (although multiple threads
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# may decode it if they all get in here at the same time, but meh
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# thats ok).
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if self._decoded_buffer is None:
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self._decoded_buffer = self.buffer.decode(self.encoding)
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return self._decoded_buffer
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def __str__(self):
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return self.decoded_buffer
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class DataSourceLoader(object):
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"""Class for retrieving an available data source instance
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:param names:
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A list of possible data source names, from which the loader
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should pick. This can be used to filter the data sources
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that can be found from outside of cloudinit control.
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:param module_iterator:
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An instance of :class:`cloudinit.plugin_finder.BaseModuleIterator`,
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which is used to find possible modules where the data sources
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can be found.
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:param strategies:
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An iterator of search strategy classes, where each strategy is capable
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of filtering the data sources that can be used by cloudinit.
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Possible strategies includes serial data source search or
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parallel data source or filtering data sources according to
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some criteria (only network data sources)
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"""
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def __init__(self, names, module_iterator, strategies):
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self._names = names
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self._module_iterator = module_iterator
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self._strategies = strategies
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@staticmethod
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def _implements_source_api(module):
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"""Check if the given module implements the data source API."""
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return hasattr(module, 'data_sources')
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def _valid_modules(self):
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"""Return all the modules that are *valid*
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Valid modules are those that implements a particular API
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for declaring the data sources it exports.
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"""
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modules = self._module_iterator.list_modules()
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return filter(self._implements_source_api, modules)
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def all_data_sources(self):
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"""Get all the data source classes that this finder knows about."""
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return itertools.chain.from_iterable(
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module.data_sources()
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for module in self._valid_modules())
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def valid_data_sources(self):
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"""Get the data sources that are valid for this run."""
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data_sources = self.all_data_sources()
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# Instantiate them before passing to the strategies.
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data_sources = (data_source() for data_source in data_sources)
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for strategy_instance in self._strategies:
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data_sources = strategy_instance.search_data_sources(data_sources)
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return data_sources
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@six.add_metaclass(abc.ABCMeta)
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class BaseDataSource(object):
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"""Base class for the data sources."""
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datasource_config = {}
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def __init__(self, config=None):
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self._cache = {}
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# TODO(cpopa): merge them instead.
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self._config = config or self.datasource_config
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def _get_cache_data(self, path):
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"""Do a metadata lookup for the given *path*
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This will return the available metadata under *path*,
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while caching the result, so that a next call will not do
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an additional API call.
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"""
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if path not in self._cache:
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self._cache[path] = self._get_data(path)
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return self._cache[path]
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@abc.abstractmethod
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def load(self):
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"""Try to load this metadata service.
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This should return ``True`` if the service was loaded properly,
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``False`` otherwise.
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"""
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@abc.abstractmethod
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def _get_data(self, path):
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"""Retrieve the metadata exported under the `path` key.
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This should return an instance of :class:`APIResponse`.
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"""
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@abc.abstractmethod
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def version(self):
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"""Get the version of the current data source."""
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def instance_id(self):
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"""Get this instance's id."""
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def user_data(self):
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"""Get the user data available for this instance."""
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def vendor_data(self):
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"""Get the vendor data available for this instance."""
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def host_name(self):
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"""Get the hostname available for this instance."""
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def public_keys(self):
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"""Get the public keys available for this instance."""
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def network_config(self):
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"""Get the specified network config, if any."""
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def admin_password(self):
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"""Get the admin password."""
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def post_password(self, password):
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"""Post the password to the metadata service."""
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def can_update_password(self):
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"""Check if this data source can update the admin password."""
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def is_password_changed(self):
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"""Check if the data source has a new password for this instance."""
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return False
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def is_password_set(self):
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"""Check if the password was already posted to the metadata service."""
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def get_data_source(names, module_iterator, strategies=None):
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"""Get an instance of any data source available.
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:param names:
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A list of possible data source names, from which the loader
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should pick. This can be used to filter the data sources
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that can be found from outside of cloudinit control.
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:param module_iterator:
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A subclass of :class:`cloudinit.plugin_finder.BaseModuleIterator`,
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which is used to find possible modules where the data sources
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can be found.
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:param strategies:
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An iterator of search strategy classes, where each strategy is capable
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of filtering the data sources that can be used by cloudinit.
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"""
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if names:
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default_strategies = [strategy.FilterNameStrategy(names)]
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else:
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default_strategies = []
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if strategies is None:
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strategies = []
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strategy_instances = [strategy_cls() for strategy_cls in strategies]
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strategies = default_strategies + strategy_instances
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iterator = module_iterator(sources.__path__)
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loader = DataSourceLoader(names, iterator, strategies)
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valid_sources = loader.valid_data_sources()
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data_source = next(valid_sources, None)
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if not data_source:
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raise exceptions.CloudInitError('No available data source found')
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return data_source
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