root / snf-common / synnefo / settings / setup.py @ 32401481
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# Copyright 2013 GRNET S.A. All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or
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# without modification, are permitted provided that the following
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# conditions are met:
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#
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# 1. Redistributions of source code must retain the above
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# copyright notice, this list of conditions and the following
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# disclaimer.
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#
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# 2. Redistributions in binary form must reproduce the above
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# copyright notice, this list of conditions and the following
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# disclaimer in the documentation and/or other materials
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# provided with the distribution.
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#
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# THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS
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# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR
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# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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# POSSIBILITY OF SUCH DAMAGE.
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#
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# The views and conclusions contained in the software and
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# documentation are those of the authors and should not be
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# interpreted as representing official policies, either expressed
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# or implied, of GRNET S.A.
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from collections import defaultdict |
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from pprint import pformat |
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from textwrap import wrap |
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from itertools import chain |
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from os import environ |
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class Setting(object): |
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"""Setting is the parent class of all setting annotations.
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Setting.initialize_settings() will register a dictionary
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of setting names to Setting instances, process all
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annotations.
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Setting.load_configuration() will load user-specific
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configurations to the defaults.
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A setting set in this stage will be flagged 'configured'.
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Those that are not set in this stage will be flagged 'default'.
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Setting.configure_settings() will post-process all settings,
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maintaining the various registries and calling configuration
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callbacks for auto-generation or validation.
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A setting has the following attributes:
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** CONFIGURATION ATTRIBUTES **
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default_value:
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The default value to be assigned if not given any by the
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administrator in the config files. To omit a default value
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assign Setting.NoValue to it.
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example_value:
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A value to serve as an informative guide for those who
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want to configure the setting. The default_value might not
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be that informative.
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description:
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Setting description for administrators and developers.
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category:
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An all-lowercase category name for grouping settings together.
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dependencies:
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A list of setting names and categories whose values will be
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given as input to configure_callback.
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configure_callback:
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A function that accepts three arguments, a Setting instance,
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the corresponding setting value given by the configuration
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files, and a dictionary with all setting dependencies declared.
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If the setting value has not be set by a config file,
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then its value (second argument) will be Setting.NoValue.
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If no value was provided by a config file, the callback must
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return the final setting value which will be assigned to it.
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If a value was provided, the callback must return
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Setting.NoValue to acknowledge it.
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export:
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If export is false then the setting will be marked not to be
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advertised in user-friendly lists or files.
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** STATE ATTRIBUTES **
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setting_name:
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This is the name this setting annotation was given to.
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Initialized as None. Settings.initialize_settings will set it.
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configured_value:
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This is the value given by a configuration file.
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If it does not exist, then the setting was not set by
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the administrator.
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Initialized as Setting.NoValue.
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Settings.load_configuration will set it.
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configured_source:
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This is the source (e.g. configuration file path) where the
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setting was configured. It is None if the setting has not
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been configured.
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configured_depth:
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The depth of the setting in the dependency tree (forest).
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runtime_value:
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This is the final setting value after all configuration
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processing. Its existence indicates that all processing
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for this setting has been completed.
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Initialized as Setting.NoValue.
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Settings.configure_one_setting will set it upon completion.
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serial:
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The setting's serial index in the 'registry' catalog.
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Represents the chronological order of execution of its annotation.
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dependents:
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A list of the names of the settings that depend on this one.
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fail_exception:
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If the configuration of a setting has failed, this holds
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the exception raised, marking it as failed to prevent
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further attempts, and to be able to re-raise the error.
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Initialized as None.
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Subclasses may expose any subset of the above, as well as additional
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attributes of their own.
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Setting will construct certain setting catalogs during runtime
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initialization, later accessible via a 'Catalogs' class attribute
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dictionary:
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catalog = Setting.Catalogs['catalog_name']
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The catalogs are:
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1. Catalog 'settings'
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A catalog of all setting annotations collected at initialization.
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This is useful to access setting annotations at runtime,
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for example a setting's default value:
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settings = Setting.Catalogs['settings']
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settings['SOCKET_CONNECT_RETRIES'].default_value
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2. Catalog 'types'
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A catalog of the different types of settings.
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At each Setting instantiation, the (sub)class attribute
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'setting_type' will be used as the setting type name in the
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catalog. Each entry in the catalog is a dictionary of setting
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names and setting annotation instances. For example:
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setting_types = Setting.Catalogs['types']
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setting_types['mandatory']['SETTING_NAME'] == setting_instance
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3. Catalog 'categories'
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A catalog of the different setting categories.
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At each Setting instantiation, the instance attribute 'category'
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will be used to group settings in categories. For example:
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categories = Setting.Catalogs['categories']
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categories['django']['SETTING_NAME'] == setting_instance
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4. Catalog 'defaults'
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A catalog of all settings that have been initialized and their
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default, pre-configuration values. This catalog is useful as
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input to the configuration from files.
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5. Catalog 'configured'
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A catalog of all settings that were configured by the
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administrator in the configuration files. Very relevant
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to the administrator as it effectively represents the
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deployment-specific configuration, without noise from
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all settings left default.
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Each setting is registered in the catalog just before
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the configure_callback is called.
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The catalog values are final setting values, not instances.
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configured = Setting.Catalogs['configured']
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print '\n'.join(("%s = %s" % it) for it in configured.items())
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5. Catalog 'runtime'
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A catalog of all finalized settings and their runtime values.
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This is output of the setting configuration process and
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where setting values must be read from at runtime.
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"""
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class SettingsError(Exception): |
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pass
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NoValue = type('NoValue', (), {}) |
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setting_type = 'setting'
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_serial = 0
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Catalogs = { |
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'registry': {},
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'settings': {},
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'types': defaultdict(dict), |
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'categories': defaultdict(dict), |
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'defaults': {},
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'configured': {},
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'runtime': {},
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} |
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default_value = None
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example_value = None
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description = 'This setting is missing documentation'
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category = 'misc'
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dependencies = () |
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dependents = () |
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export = True
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serial = None
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configured_value = NoValue |
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configured_source = None
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configured_depth = 0
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runtime_value = NoValue |
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fail_exception = None
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def __repr__(self): |
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flags = [] |
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if self.configured_value is not Setting.NoValue: |
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flags.append("configured")
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value = self.configured_value
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else:
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flags.append("default")
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value = self.default_value
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if self.runtime_value is not Setting.NoValue: |
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flags.append("finalized")
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if self.fail_exception is not None: |
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flags.append("failed({0})".format(self.fail_exception)) |
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r = "<{setting_type}[{flags}]: {value}>"
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r = r.format(setting_type=self.setting_type,
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value=repr(value),
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flags=','.join(flags))
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return r
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__str__ = __repr__ |
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def present_as_comment(self): |
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header = "# {name}: type {type}, category '{categ}'"
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header = header.format(name=self.setting_name,
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type=self.setting_type.upper(),
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categ=self.category)
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header = [header] |
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if self.dependencies: |
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header += ["# Depends on: "]
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header += ["# " + d for d in sorted(self.dependencies)] |
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description = wrap(self.description, 70) |
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description = [("# " + s) for s in description] |
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example_value = self.example_value
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default_value = self.default_value
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if example_value != default_value:
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example = "Example value: {0}"
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example = example.format(pformat(example_value)).split('\n')
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description += ["# "]
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description += [("# " + s) for s in example] |
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assignment = "{name} = {value}"
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assignment = assignment.format(name=self.setting_name,
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value=pformat(default_value)) |
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assignment = [("#" + s) for s in assignment.split('\n')] |
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return '\n'.join(chain(header, ['#'], |
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description, ['#'],
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assignment)) |
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@staticmethod
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def configure_callback(setting, value, dependencies): |
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if value is Setting.NoValue: |
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return setting.default_value
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else:
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# by default, acknowledge the configured value
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# and allow it to be used.
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return Setting.NoValue
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def validate(self): |
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"""Example setting validate method"""
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NoValue = Setting.NoValue |
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setting_name = self.setting_name
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if self is not Setting.Catalogs['settings'][setting_name]: |
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raise AssertionError() |
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runtime_value = self.runtime_value
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if runtime_value is NoValue: |
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raise AssertionError() |
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configured_value = self.configured_value
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if configured_value not in (NoValue, runtime_value): |
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raise AssertionError() |
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def __init__(self, **kwargs): |
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attr_names = ['default_value', 'example_value', 'description', |
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'category', 'dependencies', 'configure_callback', |
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'export']
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for name in attr_names: |
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if name in kwargs: |
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setattr(self, name, kwargs[name]) |
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serial = Setting._serial |
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Setting._serial = serial + 1
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registry = Setting.Catalogs['registry']
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self.serial = serial
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registry[serial] = self
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@staticmethod
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def is_valid_setting_name(name): |
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return name.isupper() and not name.startswith('_') |
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@staticmethod
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def get_settings_from_object(settings_object): |
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var_list = [] |
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is_valid_setting_name = Setting.is_valid_setting_name |
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for name in dir(settings_object): |
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if not is_valid_setting_name(name): |
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continue
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var_list.append((name, getattr(settings_object, name)))
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return var_list
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@staticmethod
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def initialize_settings(settings_dict, strict=False): |
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Catalogs = Setting.Catalogs |
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settings = Catalogs['settings']
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categories = Catalogs['categories']
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defaults = Catalogs['defaults']
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types = Catalogs['types']
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for name, value in settings_dict.iteritems(): |
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if not isinstance(value, Setting): |
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if strict:
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m = "Setting name '{name}' has non-annotated value '{value}'!"
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m = m.format(name=name, value=value) |
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raise Setting.SettingsError(m)
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else:
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value = Setting(default_value=value) |
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# FIXME: duplicate annotations?
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#if name in settings:
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# m = ("Duplicate annotation for setting '{name}': '{value}'. "
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# "Original annotation: '{original}'")
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# m = m.format(name=name, value=value, original=settings[name])
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# raise Setting.SettingsError(m)
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value.setting_name = name |
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settings[name] = value |
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categories[value.category][name] = value |
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types[value.setting_type][name] = value |
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default_value = value.default_value |
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defaults[name] = default_value |
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defaults['_SETTING_CATALOGS'] = Catalogs
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@staticmethod
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def load_settings_from_file(path, settings_dict=None): |
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if settings_dict is None: |
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settings_dict = {} |
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new_settings = {} |
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execfile(path, settings_dict, new_settings)
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return new_settings
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@staticmethod
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def load_configuration(new_settings, |
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source='unknonwn',
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allow_override=False,
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allow_unknown=False,
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allow_known=True):
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settings = Setting.Catalogs['settings']
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defaults = Setting.Catalogs['defaults']
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configured = Setting.Catalogs['configured']
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is_valid_setting_name = Setting.is_valid_setting_name |
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for name, value in new_settings.iteritems(): |
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if not is_valid_setting_name(name): |
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# silently ignore it?
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continue
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if name in settings: |
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if not allow_known: |
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m = ("{source}: setting '{name} = {value}' not allowed to "
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"be set here")
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m = m.format(source=source, name=name, value=value) |
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raise Setting.SettingsError(m)
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else:
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if allow_unknown:
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# pretend this was declared in a default settings module
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desc = "Unknown setting from {source}".format(source=source)
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setting = Setting(default_value=value, |
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category='unknown',
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description=desc) |
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Setting.initialize_settings({name: setting}, strict=True)
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else:
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m = ("{source}: unknown setting '{name} = {value}' not "
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"allowed to be set here")
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m = m.format(source=source, name=name, value=value) |
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raise Setting.SettingsError(m)
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if not allow_override and name in configured: |
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m = ("{source}: new setting '{name} = {value}' "
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"overrides setting '{name} = {oldval}'")
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m = m.format(source=source, name=name, value=value, |
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oldval=defaults[name]) |
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raise Setting.SettingsError(m)
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# setting has been accepted for configuration
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setting = settings[name] |
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setting.configured_value = value |
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setting.configured_source = source |
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configured[name] = value |
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defaults[name] = value |
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return new_settings
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@staticmethod
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def configure_one_setting(setting_name, dep_stack=()): |
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dep_stack += (setting_name,) |
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Catalogs = Setting.Catalogs |
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settings = Catalogs['settings']
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runtime = Catalogs['runtime']
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NoValue = Setting.NoValue |
450 |
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if setting_name not in settings: |
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m = "Unknown setting '{name}'"
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m = m.format(name=setting_name) |
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raise Setting.SettingsError(m)
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setting = settings[setting_name] |
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if setting.runtime_value is not NoValue: |
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# already configured, nothing to do.
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return
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if setting.fail_exception is not None: |
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# it has previously failed, re-raise the error
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exc = setting.fail_exception |
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if not isinstance(exc, Exception): |
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exc = Setting.SettingsError(str(exc))
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raise exc
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setting_value = setting.configured_value |
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if isinstance(setting_value, Setting): |
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m = ("Unprocessed setting annotation '{name} = {value}' "
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"in setting configuration stage!")
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m = m.format(name=setting_name, value=setting_value) |
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raise AssertionError(m) |
474 |
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configure_callback = setting.configure_callback |
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if not configure_callback: |
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setting.runtime_value = setting_value |
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return
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if not callable(configure_callback): |
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m = ("attribute 'configure_callback' of "
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"'{setting}' is not callable!")
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m = m.format(setting=setting) |
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exc = Setting.SettingsError(m) |
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setting.fail_exception = exc |
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raise exc
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deps = {} |
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for dep_name in setting.dependencies: |
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if dep_name not in settings: |
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m = ("Unknown dependecy setting '{dep_name}' "
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"for setting '{name}'!")
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m = m.format(dep_name=dep_name, name=setting_name) |
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raise Setting.SettingsError(m)
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if dep_name in dep_stack: |
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m = "Settings dependency cycle detected: {stack}"
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m = m.format(stack=dep_stack) |
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exc = Setting.SettingsError(m) |
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setting.fail_exception = exc |
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raise exc
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|
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dep_setting = settings[dep_name] |
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if dep_setting.fail_exception is not None: |
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m = ("Cannot configure setting {name} because it depends "
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"on '{dep}' which has failed to configure.")
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m = m.format(name=setting_name, dep=dep_name) |
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exc = Setting.SettingsError(m) |
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setting.fail_exception = exc |
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raise exc
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|
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if dep_setting.runtime_value is NoValue: |
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Setting.configure_one_setting(dep_name, dep_stack) |
514 |
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dep_value = dep_setting.runtime_value |
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deps[dep_name] = dep_value |
517 |
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try:
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new_value = configure_callback(setting, setting_value, deps) |
520 |
except Setting.SettingsError as e: |
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setting.fail_exception = e |
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raise
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|
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if new_value is not NoValue: |
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if setting_value is not NoValue: |
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m = ("Configure callback of setting '{name}' does not "
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"acknowledge the fact that a value '{value}' was "
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"provided by '{source}' and wants to assign "
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"a value '{newval}' anyway!")
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m = m.format(name=setting_name, value=setting_value, |
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source=setting.configured_source, |
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newval=new_value) |
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exc = Setting.SettingsError(m) |
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setting.fail_exception = exc |
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raise exc
|
536 |
else:
|
537 |
setting_value = new_value |
538 |
|
539 |
setting.runtime_value = setting_value |
540 |
runtime[setting_name] = setting_value |
541 |
|
542 |
@staticmethod
|
543 |
def configure_settings(setting_names=()): |
544 |
settings = Setting.Catalogs['settings']
|
545 |
if not setting_names: |
546 |
setting_names = settings.keys() |
547 |
|
548 |
bottom = set(settings.keys())
|
549 |
for name, setting in settings.iteritems(): |
550 |
dependencies = setting.dependencies |
551 |
if not dependencies: |
552 |
continue
|
553 |
bottom.discard(name) |
554 |
for dep_name in setting.dependencies: |
555 |
dep_setting = settings[dep_name] |
556 |
if not dep_setting.dependents: |
557 |
dep_setting.dependents = [] |
558 |
dep_setting.dependents.append(name) |
559 |
|
560 |
depth = 1
|
561 |
while True: |
562 |
dependents = [] |
563 |
for name in bottom: |
564 |
setting = settings[name] |
565 |
setting.configured_depth = depth |
566 |
dependents.extend(setting.dependents) |
567 |
if not dependents: |
568 |
break
|
569 |
bottom = dependents |
570 |
depth += 1
|
571 |
|
572 |
failed = [] |
573 |
for name in Setting.Catalogs['settings']: |
574 |
try:
|
575 |
Setting.configure_one_setting(name) |
576 |
except Setting.SettingsError as e: |
577 |
failed.append(e) |
578 |
|
579 |
if failed:
|
580 |
import sys |
581 |
sys.stderr.write('\n')
|
582 |
sys.stderr.write('\n'.join(map(str, failed))) |
583 |
sys.stderr.write('\n\n')
|
584 |
raise Setting.SettingsError("Failed to configure settings.") |
585 |
|
586 |
@staticmethod
|
587 |
def enforce_not_configurable(setting, value, deps=None): |
588 |
if value is not Setting.NoValue: |
589 |
m = "Setting '{name}' is not configurable."
|
590 |
m = m.format(name=setting.setting_name) |
591 |
raise Setting.SettingsError(m)
|
592 |
return setting.default_value
|
593 |
|
594 |
|
595 |
class Mandatory(Setting): |
596 |
"""Mandatory settings have to be to be configured by the
|
597 |
administrator in the configuration files. There are no defaults,
|
598 |
and not giving a value will raise an exception.
|
599 |
|
600 |
"""
|
601 |
setting_type = 'mandatory'
|
602 |
|
603 |
def __init__(self, example_value=Setting.NoValue, **kwargs): |
604 |
if example_value is Setting.NoValue: |
605 |
m = "Mandatory settings require an example_value"
|
606 |
raise Setting.SettingsError(m)
|
607 |
kwargs['example_value'] = example_value
|
608 |
kwargs['export'] = True |
609 |
Setting.__init__(self, **kwargs)
|
610 |
|
611 |
@staticmethod
|
612 |
def configure_callback(setting, value, deps): |
613 |
if value is Setting.NoValue: |
614 |
if environ.get('SYNNEFO_RELAX_MANDATORY_SETTINGS'): |
615 |
return setting.example_value
|
616 |
|
617 |
m = ("Setting '{name}' is mandatory. "
|
618 |
"Please provide a real value. "
|
619 |
"Example value: '{example}'")
|
620 |
m = m.format(name=setting.setting_name, |
621 |
example=setting.example_value) |
622 |
raise Setting.SettingsError(m)
|
623 |
|
624 |
return Setting.NoValue
|
625 |
|
626 |
|
627 |
class Default(Setting): |
628 |
"""Default settings are not mandatory.
|
629 |
There are default values that are meant to work well, and also serve as an
|
630 |
example if no explicit example is given.
|
631 |
|
632 |
"""
|
633 |
setting_type = 'default'
|
634 |
|
635 |
def __init__(self, default_value=Setting.NoValue, |
636 |
description="No description", **kwargs):
|
637 |
if default_value is Setting.NoValue: |
638 |
m = "Default settings require a default_value"
|
639 |
raise Setting.SettingsError(m)
|
640 |
|
641 |
kwargs['default_value'] = default_value
|
642 |
if 'example_value' not in kwargs: |
643 |
kwargs['example_value'] = default_value
|
644 |
kwargs['description'] = description
|
645 |
Setting.__init__(self, **kwargs)
|
646 |
|
647 |
|
648 |
class Constant(Setting): |
649 |
"""Constant settings are a like defaults, only they are not intended to be
|
650 |
visible or configurable by the administrator.
|
651 |
|
652 |
"""
|
653 |
setting_type = 'constant'
|
654 |
|
655 |
def __init__(self, default_value=Setting.NoValue, |
656 |
description="No description", **kwargs):
|
657 |
if default_value is Setting.NoValue: |
658 |
m = "Constant settings require a default_value"
|
659 |
raise Setting.SettingsError(m)
|
660 |
|
661 |
kwargs['default_value'] = default_value
|
662 |
if 'example_value' not in kwargs: |
663 |
kwargs['example_value'] = default_value
|
664 |
kwargs['export'] = False |
665 |
kwargs['description'] = description
|
666 |
Setting.__init__(self, **kwargs)
|
667 |
|
668 |
|
669 |
class Auto(Setting): |
670 |
"""Auto settings can be computed automatically.
|
671 |
Administrators may attempt to override them and the setting
|
672 |
may or may not accept being overriden. If override is not accepted
|
673 |
it will result in an error, not in a silent discarding of user input.
|
674 |
|
675 |
"""
|
676 |
setting_type = 'auto'
|
677 |
|
678 |
def __init__(self, configure_callback=None, **kwargs): |
679 |
if not configure_callback: |
680 |
m = "Auto settings must provide a configure_callback"
|
681 |
raise Setting.SettingsError(m)
|
682 |
|
683 |
kwargs['configure_callback'] = configure_callback
|
684 |
Setting.__init__(self, **kwargs)
|
685 |
|
686 |
@staticmethod
|
687 |
def configure_callback(setting, value, deps): |
688 |
raise NotImplementedError() |
689 |
|
690 |
|
691 |
class Deprecated(object): |
692 |
"""Deprecated settings must be removed, renamed, or otherwise fixed."""
|
693 |
|
694 |
setting_type = 'deprecated'
|
695 |
|
696 |
def __init__(self, rename_to=None, **kwargs): |
697 |
self.rename_to = rename_to
|
698 |
kwargs['export'] = False |
699 |
Setting.__init__(self, **kwargs)
|
700 |
|
701 |
@staticmethod
|
702 |
def configure_callback(setting, value, deps): |
703 |
m = ("Setting {name} has been deprecated. "
|
704 |
"Please consult upgrade notes and ")
|
705 |
|
706 |
if setting.rename_to:
|
707 |
m += "rename to {rename_to}."
|
708 |
else:
|
709 |
m += "remove it."
|
710 |
|
711 |
m = m.format(name=setting.setting_name, rename_to=setting.rename_to) |
712 |
raise Setting.SettingsError(m)
|
713 |
|