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372 lines
13 KiB
372 lines
13 KiB
"""
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Configuration management module. Enables configuration to be validated against
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requirement definitions before being loaded and used.
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Compatible with both raw config data structures and TOML files, config data must
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start with a root dict containing named "config bundles". These are intended to
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refer to different modular parts of the application needing configuration, and the
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config data structure must contain at least one.
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Each config bundle itself needs to have a dict at the root, and so in practice a minimal
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TOML config file would look like::
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[myapp]
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config_thingy_a = "foooooo!"
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important_number = 8237
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This would resolve to a config bundle named "myapp" that results in the dict::
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{"config_thingy_a": "foooooo!", "important_number": 8237}
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Root items that are not dicts are not supported, for instance both the following TOML files would fail::
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[[myapp]]
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important_number = 8237
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[[myapp]]
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another_important_number = 2963
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(root object in bundle is a list)
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::
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root_thingy = 46
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(root object in config is a single value)
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"""
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import re
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import toml
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from abc import ABC, abstractmethod
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from .freezedry import freezedryable, rehydrate
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class InvalidConfigError(Exception):
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pass
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# The Table and Array terms from the TOML convention essentially
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# map directly to Dictionaries (Tables), and Lists (Arrays)
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class _ConfigDefinition(ABC):
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def __init__(self, default=None, optional=False, helptext=""):
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self.default = default
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self.optional = optional
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self.helptext = helptext
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@abstractmethod
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def validate(self, value):
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pass
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@freezedryable
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class BoolDef(_ConfigDefinition):
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def __init__(self, default=None, optional=False, helptext=""):
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super().__init__(default, optional, helptext)
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def validate(self, value):
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if not isinstance(value, bool):
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raise InvalidConfigError("Config value must be a boolean")
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@freezedryable
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class IntDef(_ConfigDefinition):
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def __init__(self, default=None, minval=None, maxval=None,
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optional=False, helptext=""):
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super().__init__(default, optional, helptext)
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self.minval = minval
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self.maxval = maxval
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def validate(self, value):
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if not isinstance(value, int):
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raise InvalidConfigError("Config value must be an integer")
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if self.minval is not None and value < self.minval:
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raise InvalidConfigError("Config value must be >= " +
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str(self.minval))
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if self.maxval is not None and value > self.maxval:
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raise InvalidConfigError("Config value must be <= " +
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str(self.maxval))
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@freezedryable
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class StringDef(_ConfigDefinition):
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def __init__(self, default="", minlength=None, maxlength=None,
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optional=False, helptext=""):
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super().__init__(default, optional, helptext)
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self.minlength = minlength
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self.maxlength = maxlength
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def validate(self, value):
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if not isinstance(value, str):
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raise InvalidConfigError(F"Config value must be a string and is {value}")
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if self.minlength is not None and len(value) < self.minlength:
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raise InvalidConfigError("Config string length must be >= " +
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str(self.minlength))
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if self.maxlength is not None and len(value) > self.maxlength:
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raise InvalidConfigError("Config string length must be <= " +
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str(self.maxlength))
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@freezedryable
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class DictDef(_ConfigDefinition):
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def __init__(self, default=None, optional=False, helptext=""):
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super().__init__(default, optional, helptext)
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self.def_dict = {}
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def add_def(self, name, newdef):
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if not isinstance(newdef, _ConfigDefinition):
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raise TypeError("Config definiton must be an instance of a "
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"ConfigDefinition subclass")
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if not isinstance(name, str):
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raise TypeError("Config definition name must be a string")
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self.def_dict[name] = newdef
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return newdef
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def validate(self, value_dict): # pylint: disable=W0221
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def_set = set(self.def_dict.keys())
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value_set = set(value_dict.keys())
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for missing_key in def_set - value_set:
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if not self.def_dict[missing_key].optional:
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raise InvalidConfigError("Dict must contain key: " +
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missing_key)
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else:
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value_dict[missing_key] = self.def_dict[missing_key].default
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for extra_key in value_set - def_set:
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raise InvalidConfigError("Dict contains unknown key: " +
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extra_key)
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for key, value in value_dict.items():
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try:
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self.def_dict[key].validate(value)
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except InvalidConfigError as e:
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e.args = ("Key: " + key,) + e.args
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raise
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def get_template(self, include_optional=False):
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"""
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Return a config dict with the minimum structure required for this ConfigDefinition.
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Default values will be included, though not all required fields will necessarily have
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defaults that successfully validate.
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Args:
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include_optional: If set true, will include *all* config fields, not just the
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required ones
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Returns:
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Dict containing the structure that should be passed back in (with values) to comply
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with this ConfigDefinition.
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"""
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template = {}
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for key, confdef in self.def_dict.items():
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if confdef.optional and (not include_optional):
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continue
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if hasattr(confdef,"get_template"):
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template[key]=confdef.get_template(include_optional)
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else:
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template[key]=confdef.default
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return template
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class _ListDefMixin():
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def validate(self, value_list):
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if not isinstance(value_list, list):
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raise InvalidConfigError("Config item must be a list")
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for index, value in enumerate(value_list):
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try:
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super().validate(value)
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except InvalidConfigError as e:
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e.args = ("List index: " + str(index),) + e.args
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raise
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def get_template(self, include_optional=False):
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if hasattr(super(),"get_template"):
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return [super().get_template(include_optional)]
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else:
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return [self.default]
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@freezedryable
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class BoolListDef(_ListDefMixin, BoolDef):
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pass
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@freezedryable
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class IntListDef(_ListDefMixin, IntDef):
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pass
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@freezedryable
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class StringListDef(_ListDefMixin, StringDef):
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pass
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@freezedryable
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class DictListDef(_ListDefMixin, DictDef):
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pass
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@freezedryable
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class ConfDefinition(DictDef):
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pass
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class ConfigManager():
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def __init__(self):
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self.root_config = {}
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self.confdefs = {}
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def load(self, source):
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"""
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Load a config source into the ConfigManager, replacing any existing config.
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Args:
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source: Either a dict config to load directly, a filepath to a TOML file,
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or an open file.
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"""
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if isinstance(source, dict): # load from dict
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self.root_config = source
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elif isinstance(source, str): # load from pathname
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with open(source, 'r') as conf_file:
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self.root_config = toml.load(conf_file)
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else: # load from file
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self.root_config = toml.load(source)
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def load_overlay(self, source):
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"""
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Load a config source into the ConfigManager, merging it over the top of any existing
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config. Dicts will be recursively processed with keys being merged and existing values
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being replaced by the new source. This includes lists, which will be treated as any other
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value and completely replaced.
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Args:
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source: Either the root dict of a data structure to load directly, a filepath to a TOML file,
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or an open TOML file.
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"""
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if isinstance(source, dict): # load from dict
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new_source = source
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elif isinstance(source, str): # load from pathname
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with open(source, 'r') as conf_file:
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new_source = toml.load(conf_file)
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else: # load from file
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new_source = toml.load(source)
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self._overlay(new_source, self.root_config)
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def add_confdef(self, bundle_name, confdef):
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"""
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Stores a ConfigDefinition for future use when validating the corresponding config bundle
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Args:
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bundle_name (str) : The name to store the config definition under.
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confdef (ConfigDefinition): The populated ConfigDefinition to store.
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"""
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self.confdefs[bundle_name]=confdef
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def add_confdefs(self, confdefs):
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"""
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Stores multiple ConfigDefinitions at once for future use when validating the corresponding config bundles
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Args:
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confdefs : A dict of populated ConfigDefinitions to store, using their keys as names.
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"""
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self.confdefs.update(confdefs)
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def list_missing_confdefs(self):
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"""
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Returns a list of config bundle names that do not have a corresponding ConfigDefinition
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stored in the ConfigManager.
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"""
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return list(self.root_config.keys() - self.confdefs.keys())
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def _overlay(self, src, dest):
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for key in src:
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# If the key is also in the dest and both are dicts, merge them.
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if key in dest and isinstance(src[key], dict) and isinstance(dest[key], dict):
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self._overlay(src[key], dest[key])
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else:
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# Otherwise it's either an existing value to be replaced or needs to be added.
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dest[key] = src[key]
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def get_config_bundle(self, bundle_name, conf_def=None):
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"""
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Get a config bundle called ``bundle_name`` and validate
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it against the corresponding config definition stored in the ConfigManager.
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If ``conf_def`` is supplied, it gets used instead. Returns a validated
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config bundle dict.
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Note that as part of validation, optional keys that are missing will be
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filled in with their default values (see ``DictDef``).
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Args:
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config_name: (str) Name of the config dict to find.
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conf_def: (ConfDefinition) Optional config definition to validate against.
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"""
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if not isinstance(conf_def, ConfDefinition):
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conf_def = self.confdefs[bundle_name]
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if bundle_name not in self.root_config:
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raise InvalidConfigError(
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"Config must contain dict: " + bundle_name)
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try:
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conf_def.validate(self.root_config[bundle_name])
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except InvalidConfigError as e:
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e.args = ("Module: " + bundle_name,) + e.args
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raise
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return self.root_config[bundle_name]
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def get_config_bundles(self, bundle_names):
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"""
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Get multiple config bundles from the root dict at once, validating each one with the
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corresponding confdef stored in the ConfigManager.
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Args:
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bundle_names: A list of config bundle names to get. If dictionary is supplied, uses the values
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as ConfigDefinitions rather than looking up a stored one in the ConfigManager.
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Returns:
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A dict of config dicts, with keys matching those passed in ``bundle_names``.
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"""
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config_values = {}
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if isinstance(bundle_names, dict):
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for name, conf_def in bundle_names.items():
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config_values[name] = self.get_config_bundle(name, conf_def)
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else:
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for name in bundle_names:
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config_values[name] = self.get_config_bundle(name)
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return config_values
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def get_bundle_names(self):
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"""
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Returns a list of names of top level config bundles
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"""
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return list(self.root_config.keys())
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def dump_toml(self):
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return toml.dumps(self.root_config)
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def dump_to_file(self, filepath, message=None):
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with open(filepath, 'w+') as f:
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content = self.dump_toml()
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if message is not None:
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content = content.rstrip() + gen_comment(message)
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f.write(content)
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def strip_toml_message(string):
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print("stripping...")
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return re.sub("(?m)^#\\ shepherd_message:[^\\n]*$\\n?(?:^#[^\\n]+$\\n?)*",
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'', string)
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def update_toml_message(filepath, message):
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with open(filepath, 'r+') as f:
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content = f.read()
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content = strip_toml_message(content).rstrip()
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content += gen_comment(message)
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f.seek(0)
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f.write(content)
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f.truncate()
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def gen_comment(string):
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return '\n# shepherd_message: ' + '\n# '.join(string.replace('#', '').splitlines()) + '\n'
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