# -*- coding: utf-8 -*-
# This file is part of Confuse.
# Copyright 2016, Adrian Sampson.
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
"""Worry-free YAML configuration files.
"""
import errno
import os
import yaml
from collections import OrderedDict
from . import util
from . import templates
from . import yaml_util
from .sources import ConfigSource, EnvSource, YamlSource
from .exceptions import ConfigTypeError, NotFoundError, ConfigError
CONFIG_FILENAME = 'config.yaml'
DEFAULT_FILENAME = 'config_default.yaml'
ROOT_NAME = 'root'
REDACTED_TOMBSTONE = 'REDACTED'
# Views and sources.
[docs]
class ConfigView(object):
"""A configuration "view" is a query into a program's configuration
data. A view represents a hypothetical location in the configuration
tree; to extract the data from the location, a client typically
calls the ``view.get()`` method. The client can access children in
the tree (subviews) by subscripting the parent view (i.e.,
``view[key]``).
"""
name = None
"""The name of the view, depicting the path taken through the
configuration in Python-like syntax (e.g., ``foo['bar'][42]``).
"""
[docs]
def resolve(self):
"""The core (internal) data retrieval method. Generates (value,
source) pairs for each source that contains a value for this
view. May raise `ConfigTypeError` if a type error occurs while
traversing a source.
"""
raise NotImplementedError
[docs]
def first(self):
"""Return a (value, source) pair for the first object found for
this view. This amounts to the first element returned by
`resolve`. If no values are available, a `NotFoundError` is
raised.
"""
pairs = self.resolve()
try:
return util.iter_first(pairs)
except ValueError:
raise NotFoundError(u"{0} not found".format(self.name))
[docs]
def exists(self):
"""Determine whether the view has a setting in any source.
"""
try:
self.first()
except NotFoundError:
return False
return True
[docs]
def add(self, value):
"""Set the *default* value for this configuration view. The
specified value is added as the lowest-priority configuration
data source.
"""
raise NotImplementedError
[docs]
def set(self, value):
"""*Override* the value for this configuration view. The
specified value is added as the highest-priority configuration
data source.
"""
raise NotImplementedError
[docs]
def root(self):
"""The RootView object from which this view is descended.
"""
raise NotImplementedError
def __repr__(self):
return '<{}: {}>'.format(self.__class__.__name__, self.name)
def __iter__(self):
"""Iterate over the keys of a dictionary view or the *subviews*
of a list view.
"""
# Try iterating over the keys, if this is a dictionary view.
try:
for key in self.keys():
yield key
except ConfigTypeError:
# Otherwise, try iterating over a list view.
try:
for subview in self.sequence():
yield subview
except ConfigTypeError:
item, _ = self.first()
raise ConfigTypeError(
u'{0} must be a dictionary or a list, not {1}'.format(
self.name, type(item).__name__
)
)
def __getitem__(self, key):
"""Get a subview of this view."""
return Subview(self, key)
def __setitem__(self, key, value):
"""Create an overlay source to assign a given key under this
view.
"""
self.set({key: value})
def __contains__(self, key):
return self[key].exists()
[docs]
def set_args(self, namespace, dots=False):
"""Overlay parsed command-line arguments, generated by a library
like argparse or optparse, onto this view's value.
:param namespace: Dictionary or Namespace to overlay this config with.
Supports nested Dictionaries and Namespaces.
:type namespace: dict or Namespace
:param dots: If True, any properties on namespace that contain dots (.)
will be broken down into child dictionaries.
:Example:
{'foo.bar': 'car'}
# Will be turned into
{'foo': {'bar': 'car'}}
:type dots: bool
"""
self.set(util.build_dict(namespace, sep='.' if dots else ''))
# Magical conversions. These special methods make it possible to use
# View objects somewhat transparently in certain circumstances. For
# example, rather than using ``view.get(bool)``, it's possible to
# just say ``bool(view)`` or use ``view`` in a conditional.
def __str__(self):
"""Get the value for this view as a bytestring.
"""
return str(self.get())
def __bool__(self):
"""Gets the value for this view as a bool.
"""
return bool(self.get())
# Dictionary emulation methods.
[docs]
def keys(self):
"""Returns a list containing all the keys available as subviews
of the current views. This enumerates all the keys in *all*
dictionaries matching the current view, in contrast to
``view.get(dict).keys()``, which gets all the keys for the
*first* dict matching the view. If the object for this view in
any source is not a dict, then a `ConfigTypeError` is raised. The
keys are ordered according to how they appear in each source.
"""
keys = []
for dic, _ in self.resolve():
try:
cur_keys = dic.keys()
except AttributeError:
raise ConfigTypeError(
u'{0} must be a dict, not {1}'.format(
self.name, type(dic).__name__
)
)
for key in cur_keys:
if key not in keys:
keys.append(key)
return keys
[docs]
def items(self):
"""Iterates over (key, subview) pairs contained in dictionaries
from *all* sources at this view. If the object for this view in
any source is not a dict, then a `ConfigTypeError` is raised.
"""
for key in self.keys():
yield key, self[key]
[docs]
def values(self):
"""Iterates over all the subviews contained in dictionaries from
*all* sources at this view. If the object for this view in any
source is not a dict, then a `ConfigTypeError` is raised.
"""
for key in self.keys():
yield self[key]
# List/sequence emulation.
[docs]
def sequence(self):
"""Iterates over the subviews contained in lists from the *first*
source at this view. If the object for this view in the first source
is not a list or tuple, then a `ConfigTypeError` is raised.
"""
try:
collection, _ = self.first()
except NotFoundError:
return
if not isinstance(collection, (list, tuple)):
raise ConfigTypeError(
u'{0} must be a list, not {1}'.format(
self.name, type(collection).__name__
)
)
# Yield all the indices in the sequence.
for index in range(len(collection)):
yield self[index]
[docs]
def all_contents(self):
"""Iterates over all subviews from collections at this view from
*all* sources. If the object for this view in any source is not
iterable, then a `ConfigTypeError` is raised. This method is
intended to be used when the view indicates a list; this method
will concatenate the contents of the list from all sources.
"""
for collection, _ in self.resolve():
try:
it = iter(collection)
except TypeError:
raise ConfigTypeError(
u'{0} must be an iterable, not {1}'.format(
self.name, type(collection).__name__
)
)
for value in it:
yield value
# Validation and conversion.
[docs]
def flatten(self, redact=False):
"""Create a hierarchy of OrderedDicts containing the data from
this view, recursively reifying all views to get their
represented values.
If `redact` is set, then sensitive values are replaced with
the string "REDACTED".
"""
od = OrderedDict()
for key, view in self.items():
if redact and view.redact:
od[key] = REDACTED_TOMBSTONE
else:
try:
od[key] = view.flatten(redact=redact)
except ConfigTypeError:
od[key] = view.get()
return od
[docs]
def get(self, template=templates.REQUIRED):
"""Retrieve the value for this view according to the template.
The `template` against which the values are checked can be
anything convertible to a `Template` using `as_template`. This
means you can pass in a default integer or string value, for
example, or a type to just check that something matches the type
you expect.
May raise a `ConfigValueError` (or its subclass,
`ConfigTypeError`) or a `NotFoundError` when the configuration
doesn't satisfy the template.
"""
return templates.as_template(template).value(self, template)
# Shortcuts for common templates.
[docs]
def as_filename(self):
"""Get the value as a path. Equivalent to `get(Filename())`.
"""
return self.get(templates.Filename())
[docs]
def as_path(self):
"""Get the value as a `pathlib.Path` object. Equivalent to `get(Path())`.
"""
return self.get(templates.Path())
[docs]
def as_choice(self, choices):
"""Get the value from a list of choices. Equivalent to
`get(Choice(choices))`.
Sequences, dictionaries and :class:`Enum` types are supported,
see :class:`confuse.templates.Choice` for more details.
"""
return self.get(templates.Choice(choices))
[docs]
def as_number(self):
"""Get the value as any number type: int or float. Equivalent to
`get(Number())`.
"""
return self.get(templates.Number())
[docs]
def as_str_seq(self, split=True):
"""Get the value as a sequence of strings. Equivalent to
`get(StrSeq(split=split))`.
"""
return self.get(templates.StrSeq(split=split))
[docs]
def as_pairs(self, default_value=None):
"""Get the value as a sequence of pairs of two strings. Equivalent to
`get(Pairs(default_value=default_value))`.
"""
return self.get(templates.Pairs(default_value=default_value))
[docs]
def as_str(self):
"""Get the value as a (Unicode) string. Equivalent to
`get(unicode)` on Python 2 and `get(str)` on Python 3.
"""
return self.get(templates.String())
[docs]
def as_str_expanded(self):
"""Get the value as a (Unicode) string, with env vars
expanded by `os.path.expandvars()`.
"""
return self.get(templates.String(expand_vars=True))
# Redaction.
@property
def redact(self):
"""Whether the view contains sensitive information and should be
redacted from output.
"""
return () in self.get_redactions()
@redact.setter
def redact(self, flag):
self.set_redaction((), flag)
[docs]
def set_redaction(self, path, flag):
"""Add or remove a redaction for a key path, which should be an
iterable of keys.
"""
raise NotImplementedError()
[docs]
def get_redactions(self):
"""Get the set of currently-redacted sub-key-paths at this view.
"""
raise NotImplementedError()
[docs]
class RootView(ConfigView):
"""The base of a view hierarchy. This view keeps track of the
sources that may be accessed by subviews.
"""
def __init__(self, sources):
"""Create a configuration hierarchy for a list of sources. At
least one source must be provided. The first source in the list
has the highest priority.
"""
self.sources = list(sources)
self.name = ROOT_NAME
self.redactions = set()
[docs]
def add(self, obj):
self.sources.append(ConfigSource.of(obj))
[docs]
def set(self, value):
self.sources.insert(0, ConfigSource.of(value))
[docs]
def resolve(self):
return ((dict(s), s) for s in self.sources)
[docs]
def clear(self):
"""Remove all sources (and redactions) from this
configuration.
"""
del self.sources[:]
self.redactions.clear()
[docs]
def root(self):
return self
[docs]
def set_redaction(self, path, flag):
if flag:
self.redactions.add(path)
elif path in self.redactions:
self.redactions.remove(path)
[docs]
def get_redactions(self):
return self.redactions
[docs]
class Subview(ConfigView):
"""A subview accessed via a subscript of a parent view."""
def __init__(self, parent, key):
"""Make a subview of a parent view for a given subscript key.
"""
self.parent = parent
self.key = key
# Choose a human-readable name for this view.
if isinstance(self.parent, RootView):
self.name = ''
else:
self.name = self.parent.name
if not isinstance(self.key, int):
self.name += '.'
if isinstance(self.key, int):
self.name += u'#{0}'.format(self.key)
elif isinstance(self.key, bytes):
self.name += self.key.decode('utf-8')
elif isinstance(self.key, str):
self.name += self.key
else:
self.name += repr(self.key)
[docs]
def resolve(self):
for collection, source in self.parent.resolve():
try:
value = collection[self.key]
except IndexError:
# List index out of bounds.
continue
except KeyError:
# Dict key does not exist.
continue
except TypeError:
# Not subscriptable.
raise ConfigTypeError(
u"{0} must be a collection, not {1}".format(
self.parent.name, type(collection).__name__
)
)
yield value, source
[docs]
def set(self, value):
self.parent.set({self.key: value})
[docs]
def add(self, value):
self.parent.add({self.key: value})
[docs]
def root(self):
return self.parent.root()
[docs]
def set_redaction(self, path, flag):
self.parent.set_redaction((self.key,) + path, flag)
[docs]
def get_redactions(self):
return (kp[1:] for kp in self.parent.get_redactions()
if kp and kp[0] == self.key)
# Main interface.
[docs]
class Configuration(RootView):
def __init__(self, appname, modname=None, read=True,
loader=yaml_util.Loader):
"""Create a configuration object by reading the
automatically-discovered config files for the application for a
given name. If `modname` is specified, it should be the import
name of a module whose package will be searched for a default
config file. (Otherwise, no defaults are used.) Pass `False` for
`read` to disable automatic reading of all discovered
configuration files. Use this when creating a configuration
object at module load time and then call the `read` method
later. Specify the Loader class as `loader`.
"""
super(Configuration, self).__init__([])
self.appname = appname
self.modname = modname
self.loader = loader
# Resolve default source location. We do this ahead of time to
# avoid unexpected problems if the working directory changes.
if self.modname:
self._package_path = util.find_package_path(self.modname)
else:
self._package_path = None
self._env_var = '{0}DIR'.format(self.appname.upper())
if read:
self.read()
[docs]
def user_config_path(self):
"""Points to the location of the user configuration.
The file may not exist.
"""
return os.path.join(self.config_dir(), CONFIG_FILENAME)
[docs]
def _add_user_source(self):
"""Add the configuration options from the YAML file in the
user's configuration directory (given by `config_dir`) if it
exists.
"""
filename = self.user_config_path()
self.add(YamlSource(filename, loader=self.loader, optional=True))
[docs]
def _add_default_source(self):
"""Add the package's default configuration settings. This looks
for a YAML file located inside the package for the module
`modname` if it was given.
"""
if self.modname:
if self._package_path:
filename = os.path.join(self._package_path, DEFAULT_FILENAME)
self.add(YamlSource(filename, loader=self.loader,
optional=True, default=True))
[docs]
def read(self, user=True, defaults=True):
"""Find and read the files for this configuration and set them
as the sources for this configuration. To disable either
discovered user configuration files or the in-package defaults,
set `user` or `defaults` to `False`.
"""
if user:
self._add_user_source()
if defaults:
self._add_default_source()
[docs]
def config_dir(self):
"""Get the path to the user configuration directory. The
directory is guaranteed to exist as a postcondition (one may be
created if none exist).
If the application's ``...DIR`` environment variable is set, it
is used as the configuration directory. Otherwise,
platform-specific standard configuration locations are searched
for a ``config.yaml`` file. If no configuration file is found, a
fallback path is used.
"""
# If environment variable is set, use it.
if self._env_var in os.environ:
appdir = os.environ[self._env_var]
appdir = os.path.abspath(os.path.expanduser(appdir))
if os.path.isfile(appdir):
raise ConfigError(u'{0} must be a directory'.format(
self._env_var
))
else:
# Search platform-specific locations. If no config file is
# found, fall back to the first directory in the list.
configdirs = util.config_dirs()
for confdir in configdirs:
appdir = os.path.join(confdir, self.appname)
if os.path.isfile(os.path.join(appdir, CONFIG_FILENAME)):
break
else:
appdir = os.path.join(configdirs[0], self.appname)
# Ensure that the directory exists.
try:
os.makedirs(appdir)
except OSError as e:
if e.errno != errno.EEXIST:
raise
return appdir
[docs]
def set_file(self, filename, base_for_paths=False):
"""Parses the file as YAML and inserts it into the configuration
sources with highest priority.
:param filename: Filename of the YAML file to load.
:param base_for_paths: Indicates whether the directory containing the
YAML file will be used as the base directory for resolving relative
path values stored in the YAML file. Otherwise, by default, the
directory returned by `config_dir()` will be used as the base.
"""
self.set(YamlSource(filename, base_for_paths=base_for_paths,
loader=self.loader))
[docs]
def set_env(self, prefix=None, sep='__'):
"""Create a configuration overlay at the highest priority from
environment variables.
After prefix matching and removal, environment variable names will be
converted to lowercase for use as keys within the configuration. If
there are nested keys, list-like dicts (ie, `{0: 'a', 1: 'b'}`) will
be converted into corresponding lists (ie, `['a', 'b']`). The values
of all environment variables will be parsed as YAML scalars using the
`self.loader` Loader class to ensure type conversion is consistent
with YAML file sources. Use the `EnvSource` class directly to load
environment variables using non-default behavior and to enable full
YAML parsing of values.
:param prefix: The prefix to identify the environment variables to use.
Defaults to uppercased `self.appname` followed by an underscore.
:param sep: Separator within variable names to define nested keys.
"""
if prefix is None:
prefix = '{0}_'.format(self.appname.upper())
self.set(EnvSource(prefix, sep=sep, loader=self.loader))
[docs]
def dump(self, full=True, redact=False):
"""Dump the Configuration object to a YAML file.
The order of the keys is determined from the default
configuration file. All keys not in the default configuration
will be appended to the end of the file.
:param full: Dump settings that don't differ from the defaults
as well
:param redact: Remove sensitive information (views with the `redact`
flag set) from the output
"""
if full:
out_dict = self.flatten(redact=redact)
else:
# Exclude defaults when flattening.
sources = [s for s in self.sources if not s.default]
temp_root = RootView(sources)
temp_root.redactions = self.redactions
out_dict = temp_root.flatten(redact=redact)
yaml_out = yaml.dump(out_dict, Dumper=yaml_util.Dumper,
default_flow_style=None, indent=4,
width=1000)
# Restore comments to the YAML text.
default_source = None
for source in self.sources:
if source.default:
default_source = source
break
if default_source and default_source.filename:
with open(default_source.filename, 'rb') as fp:
default_data = fp.read()
yaml_out = yaml_util.restore_yaml_comments(
yaml_out, default_data.decode('utf-8'))
return yaml_out
[docs]
def reload(self):
"""Reload all sources from the file system.
This only affects sources that come from files (i.e.,
`YamlSource` objects); other sources, such as dictionaries
inserted with `add` or `set`, will remain unchanged.
"""
for source in self.sources:
if isinstance(source, YamlSource):
source.load()
[docs]
class LazyConfig(Configuration):
"""A Configuration at reads files on demand when it is first
accessed. This is appropriate for using as a global config object at
the module level.
"""
def __init__(self, appname, modname=None):
super(LazyConfig, self).__init__(appname, modname, False)
self._materialized = False # Have we read the files yet?
self._lazy_prefix = [] # Pre-materialization calls to set().
self._lazy_suffix = [] # Calls to add().
[docs]
def read(self, user=True, defaults=True):
self._materialized = True
super(LazyConfig, self).read(user, defaults)
[docs]
def resolve(self):
if not self._materialized:
# Read files and unspool buffers.
self.read()
self.sources += self._lazy_suffix
self.sources[:0] = self._lazy_prefix
return super(LazyConfig, self).resolve()
[docs]
def add(self, value):
super(LazyConfig, self).add(value)
if not self._materialized:
# Buffer additions to end.
self._lazy_suffix += self.sources
del self.sources[:]
[docs]
def set(self, value):
super(LazyConfig, self).set(value)
if not self._materialized:
# Buffer additions to beginning.
self._lazy_prefix[:0] = self.sources
del self.sources[:]
[docs]
def clear(self):
"""Remove all sources from this configuration."""
super(LazyConfig, self).clear()
self._lazy_suffix = []
self._lazy_prefix = []
# "Validated" configuration views: experimental!