""" Interface definitions for Bcfg2 server plugins """
import os
import sys
import copy
import threading
import lxml.etree
import Bcfg2.Server
from Bcfg2.Compat import Queue, Empty, Full, cPickle
from Bcfg2.Server.Plugin.base import Plugin
from Bcfg2.Server.Plugin.exceptions import PluginInitError, \
MetadataRuntimeError, MetadataConsistencyError
[docs]class Generator(object):
""" Generator plugins contribute to literal client configurations.
That is, they generate entry contents.
An entry is generated in one of two ways:
#. The Bcfg2 core looks in the ``Entries`` dict attribute of the
plugin object. ``Entries`` is expected to be a dict whose keys
are entry tags (e.g., ``"Path"``, ``"Service"``, etc.) and
whose values are dicts; those dicts should map the ``name``
attribute of an entry to a callable that will be called to
generate the content. The callable will receive two arguments:
the abstract entry (as an lxml.etree._Element object), and the
client metadata object the entry is being generated for.
#. If the entry is not listed in ``Entries``, the Bcfg2 core calls
:func:`HandlesEntry`; if that returns True, then it calls
:func:`HandleEntry`.
"""
[docs] def HandlesEntry(self, entry, metadata): # pylint: disable=W0613
""" HandlesEntry is the slow path method for routing
configuration binding requests. It is called if the
``Entries`` dict does not contain a method for binding the
entry.
:param entry: The entry to bind
:type entry: lxml.etree._Element
:param metadata: The client metadata
:type metadata: Bcfg2.Server.Plugins.Metadata.ClientMetadata
:return: bool - Whether or not this plugin can handle the entry
:raises: :class:`Bcfg2.Server.Plugin.exceptions.PluginExecutionError`
"""
return False
[docs] def HandleEntry(self, entry, metadata): # pylint: disable=W0613
""" HandleEntry is the slow path method for binding
configuration binding requests. It is called if the
``Entries`` dict does not contain a method for binding the
entry, and :func:`HandlesEntry`
returns True.
:param entry: The entry to bind
:type entry: lxml.etree._Element
:param metadata: The client metadata
:type metadata: Bcfg2.Server.Plugins.Metadata.ClientMetadata
:return: lxml.etree._Element - The fully bound entry
:raises: :class:`Bcfg2.Server.Plugin.exceptions.PluginExecutionError`
"""
return entry
[docs]class Structure(object):
""" Structure Plugins contribute to abstract client
configurations. That is, they produce lists of entries that will
be generated for a client. """
[docs] def BuildStructures(self, metadata):
""" Build a list of lxml.etree._Element objects that will be
added to the top-level ``<Configuration>`` tag of the client
configuration. Consequently, each object in the list returned
by ``BuildStructures()`` must consist of a container tag
(e.g., ``<Bundle>`` or ``<Independent>``) which contains the
entry tags. It must not return a list of entry tags.
:param metadata: The client metadata
:type metadata: Bcfg2.Server.Plugins.Metadata.ClientMetadata
:return: list of lxml.etree._Element objects
"""
raise NotImplementedError
[docs]class Connector(object):
""" Connector plugins augment client metadata instances with
additional data, additional groups, or both. """
[docs] def get_additional_groups(self, metadata): # pylint: disable=W0613
""" Return a list of additional groups for the given client.
Each group can be either the name of a group (a string), or a
:class:`Bcfg2.Server.Plugins.Metadata.MetadataGroup` object
that defines other data besides just the name. Note that you
cannot return a
:class:`Bcfg2.Server.Plugins.Metadata.MetadataGroup` object
that clobbers a group defined by another plugin; the original
group will be used instead. For instance, assume the
following in ``Metadata/groups.xml``:
.. code-block:: xml
<Groups>
...
<Group name="foo" public="false"/>
</Groups>
You could not subsequently return a
:class:`Bcfg2.Server.Plugins.Metadata.MetadataGroup` object
with ``public=True``; a warning would be issued, and the
original (non-public) ``foo`` group would be used.
:param metadata: The client metadata
:type metadata: Bcfg2.Server.Plugins.Metadata.ClientMetadata
:return: list of strings or
:class:`Bcfg2.Server.Plugins.Metadata.MetadataGroup`
objects.
"""
return list()
[docs] def get_additional_data(self, metadata): # pylint: disable=W0613
""" Return arbitrary additional data for the given
ClientMetadata object. By convention this is usually a dict
object, but doesn't need to be.
:param metadata: The client metadata
:type metadata: Bcfg2.Server.Plugins.Metadata.ClientMetadata
:return: dict
"""
return dict()
[docs]class Probing(object):
""" Probing plugins can collect data from clients and process it.
"""
[docs] def GetProbes(self, metadata):
""" Return a list of probes for the given client. Each probe
should be an lxml.etree._Element object that adheres to
the following specification. Each probe must the following
attributes:
* ``name``: The unique name of the probe.
* ``source``: The origin of the probe; probably the name of
the plugin that supplies the probe.
* ``interpreter``: The command that will be run on the client
to interpret the probe script. Compiled (i.e.,
non-interpreted) probes are not supported.
The text of the XML tag should be the contents of the probe,
i.e., the code that will be run on the client.
:param metadata: The client metadata
:type metadata: Bcfg2.Server.Plugins.Metadata.ClientMetadata
:return: list of lxml.etree._Element objects
"""
raise NotImplementedError
[docs] def ReceiveData(self, metadata, datalist):
""" Process data returned from the probes for the given
client. ``datalist`` is a list of lxml.etree._Element
objects, each of which is a single tag; the ``name`` attribute
holds the unique name of the probe that was run, and the text
contents of the tag hold the results of the probe.
:param metadata: The client metadata
:type metadata: Bcfg2.Server.Plugins.Metadata.ClientMetadata
:param datalist: The probe data
:type datalist: list of lxml.etree._Element objects
:return: None
"""
raise NotImplementedError
[docs]class Statistics(Plugin):
""" Statistics plugins handle statistics for clients. In general,
you should avoid using Statistics and use
:class:`ThreadedStatistics` instead."""
create = False
[docs] def process_statistics(self, client, xdata):
""" Process the given XML statistics data for the specified
client.
:param metadata: The client metadata
:type metadata: Bcfg2.Server.Plugins.Metadata.ClientMetadata
:param data: The statistics data
:type data: lxml.etree._Element
:return: None
"""
raise NotImplementedError
[docs]class Threaded(object):
""" Threaded plugins use threads in any way. The thread must be
started after daemonization, so this class implements a single
method, :func:`start_threads`, that can be used to start threads
after daemonization of the server core. """
[docs] def start_threads(self):
""" Start this plugin's threads after daemonization.
:return: None
:raises: :class:`Bcfg2.Server.Plugin.exceptions.PluginInitError`
"""
raise NotImplementedError
[docs]class ThreadedStatistics(Statistics, Threaded, threading.Thread):
""" ThreadedStatistics plugins process client statistics in a
separate thread. """
def __init__(self, core, datastore):
Statistics.__init__(self, core, datastore)
Threaded.__init__(self)
threading.Thread.__init__(self)
# Event from the core signaling an exit
self.terminate = core.terminate
self.work_queue = Queue(100000)
self.pending_file = os.path.join(datastore, "etc",
"%s.pending" % self.name)
self.daemon = False
def start_threads(self):
self.start()
def _save(self):
"""Save any pending data to a file."""
pending_data = []
try:
while not self.work_queue.empty():
(metadata, xdata) = self.work_queue.get_nowait()
data = \
lxml.etree.tostring(xdata,
xml_declaration=False).decode("UTF-8")
pending_data.append((metadata.hostname, data))
except Empty:
pass
try:
savefile = open(self.pending_file, 'w')
cPickle.dump(pending_data, savefile)
savefile.close()
self.logger.info("Saved pending %s data" % self.name)
except (IOError, TypeError):
err = sys.exc_info()[1]
self.logger.warning("Failed to save pending data: %s" % err)
def _load(self):
"""Load any pending data from a file."""
if not os.path.exists(self.pending_file):
return True
pending_data = []
try:
savefile = open(self.pending_file, 'r')
pending_data = cPickle.load(savefile)
savefile.close()
except (IOError, cPickle.UnpicklingError):
err = sys.exc_info()[1]
self.logger.warning("Failed to load pending data: %s" % err)
return False
for (pmetadata, pdata) in pending_data:
# check that shutdown wasnt called early
if self.terminate.isSet():
return False
try:
while True:
try:
metadata = self.core.build_metadata(pmetadata)
break
except MetadataRuntimeError:
pass
self.terminate.wait(5)
if self.terminate.isSet():
return False
self.work_queue.put_nowait(
(metadata,
lxml.etree.XML(pdata, parser=Bcfg2.Server.XMLParser)))
except Full:
self.logger.warning("Queue.Full: Failed to load queue data")
break
except lxml.etree.LxmlError:
lxml_error = sys.exc_info()[1]
self.logger.error("Unable to load saved interaction: %s" %
lxml_error)
except MetadataConsistencyError:
self.logger.error("Unable to load metadata for save "
"interaction: %s" % pmetadata)
try:
os.unlink(self.pending_file)
except OSError:
self.logger.error("Failed to unlink save file: %s" %
self.pending_file)
self.logger.info("Loaded pending %s data" % self.name)
return True
def run(self):
if not self._load():
return
while not self.terminate.isSet() and self.work_queue is not None:
try:
(client, xdata) = self.work_queue.get(block=True, timeout=2)
except Empty:
continue
except:
err = sys.exc_info()[1]
self.logger.error("ThreadedStatistics: %s" % err)
continue
self.handle_statistic(client, xdata)
if self.work_queue is not None and not self.work_queue.empty():
self._save()
def process_statistics(self, metadata, data):
try:
self.work_queue.put_nowait((metadata, copy.copy(data)))
except Full:
self.logger.warning("%s: Queue is full. Dropping interactions." %
self.name)
[docs] def handle_statistic(self, metadata, data):
""" Process the given XML statistics data for the specified
client object. This differs from the
:func:`Statistics.process_statistics` method only in that
ThreadedStatistics first adds the data to a queue, and then
processes them in a separate thread.
:param metadata: The client metadata
:type metadata: Bcfg2.Server.Plugins.Metadata.ClientMetadata
:param data: The statistics data
:type data: lxml.etree._Element
:return: None
"""
raise NotImplementedError
# pylint: disable=C0111
# Someone who understands these interfaces better needs to write docs
# for PullSource and PullTarget
class PullSource(object):
def GetExtra(self, client): # pylint: disable=W0613
return []
def GetCurrentEntry(self, client, e_type, e_name):
raise NotImplementedError
class PullTarget(object):
def AcceptChoices(self, entry, metadata):
raise NotImplementedError
def AcceptPullData(self, specific, new_entry, verbose):
raise NotImplementedError
# pylint: enable=C0111
[docs]class Decision(object):
""" Decision plugins produce decision lists for affecting which
entries are actually installed on clients. """
[docs] def GetDecisions(self, metadata, mode):
""" Return a list of tuples of ``(<entry type>, <entry
name>)`` to be used as the decision list for the given
client in the specified mode.
:param metadata: The client metadata
:type metadata: Bcfg2.Server.Plugins.Metadata.ClientMetadata
:param mode: The decision mode ("whitelist" or "blacklist")
:type mode: string
:return: list of tuples
"""
raise NotImplementedError
[docs]class StructureValidator(object):
""" StructureValidator plugins can modify the list of structures
after it has been created but before the entries have been
concretely bound. """
[docs] def validate_structures(self, metadata, structures):
""" Given a list of structures (i.e., of tags that contain
entry tags), modify that list or the structures in it
in-place.
:param metadata: The client metadata
:type metadata: Bcfg2.Server.Plugins.Metadata.ClientMetadata
:param config: A list of lxml.etree._Element objects
describing the structures (i.e., bundles) for
this client. This can be modified in place.
:type config: list of lxml.etree._Element
:returns: None
:raises: :class:`Bcfg2.Server.Plugin.exceptions.ValidationError`
"""
raise NotImplementedError
[docs]class GoalValidator(object):
""" GoalValidator plugins can modify the concretely-bound configuration of
a client as a last stage before the configuration is sent to the
client. """
[docs] def validate_goals(self, metadata, config):
""" Given a monolithic XML document of the full configuration,
modify the document in-place.
:param metadata: The client metadata
:type metadata: Bcfg2.Server.Plugins.Metadata.ClientMetadata
:param config: The full configuration for the client
:type config: lxml.etree._Element
:returns: None
:raises: :class:`Bcfg2.Server.Plugin.exceptions:ValidationError`
"""
raise NotImplementedError
[docs]class Version(Plugin):
""" Version plugins interact with various version control systems. """
create = False
#: The path to the VCS metadata file or directory, relative to the
#: base of the Bcfg2 repository. E.g., for Subversion this would
#: be ".svn"
__vcs_metadata_path__ = None
def __init__(self, core, datastore):
Plugin.__init__(self, core, datastore)
if core.setup['vcs_root']:
self.vcs_root = core.setup['vcs_root']
else:
self.vcs_root = datastore
if self.__vcs_metadata_path__:
self.vcs_path = os.path.join(self.vcs_root,
self.__vcs_metadata_path__)
if not os.path.exists(self.vcs_path):
raise PluginInitError("%s is not present" % self.vcs_path)
else:
self.vcs_path = None
__init__.__doc__ = Plugin.__init__.__doc__ + """
.. autoattribute:: __vcs_metadata_path__ """
[docs] def get_revision(self):
""" Return the current revision of the Bcfg2 specification.
This will be included in the ``revision`` attribute of the
top-level tag of the XML configuration sent to the client.
:returns: string - the current version
"""
raise NotImplementedError
[docs]class ClientRunHooks(object):
""" ClientRunHooks can hook into various parts of a client run to
perform actions at various times without needing to pretend to be
a different plugin type. """
[docs] def start_client_run(self, metadata):
""" Invoked at the start of a client run, after all probe data
has been received and decision lists have been queried (if
applicable), but before the configuration is generated.
:param metadata: The client metadata object
:type metadata: Bcfg2.Server.Plugins.Metadata.ClientMetadata
:returns: None
"""
pass
[docs] def end_client_run(self, metadata):
""" Invoked at the end of a client run, immediately after
:class:`GoalValidator` plugins have been run and just before
the configuration is returned to the client.
:param metadata: The client metadata object
:type metadata: Bcfg2.Server.Plugins.Metadata.ClientMetadata
:returns: None
"""
pass
[docs] def end_statistics(self, metadata):
""" Invoked after statistics are processed for a client.
:param metadata: The client metadata object
:type metadata: Bcfg2.Server.Plugins.Metadata.ClientMetadata
:returns: None
"""
pass
[docs]class Caching(object):
""" A plugin that caches more than just the data received from the
FAM. This presents a unified interface to clear the cache. """
[docs] def expire_cache(self, key=None):
""" Expire the cache associated with the given key.
:param key: The key to expire the cache for. Because cache
implementations vary tremendously between plugins,
this could be any number of things, but generally
a hostname. It also may or may not be possible to
expire the cache for a single host; this interface
does not require any guarantee about that.
:type key: varies
:returns: None
"""
raise NotImplementedError
