class ConfigurationManager(object):
#--------------------------------------------------------------------------
def __init__(
self,
definition_source=None,
values_source_list=None,
argv_source=None,
#use_config_files=True,
use_auto_help=True,
use_admin_controls=True,
quit_after_admin=True,
options_banned_from_help=None,
app_name='',
app_version='',
app_description='',
config_pathname='.',
config_optional=True,
value_source_object_hook=DotDict,
):
"""create and initialize a configman object.
parameters:
definition_source - a namespace or list of namespaces from which
configman is to fetch the definitions of the
configuration parameters.
values_source_list - (optional) a hierarchical list of sources for
values for the configuration parameters.
As values are copied from these sources,
conficting values are resolved with sources
on the right getting preference over sources on
the left.
argv_source - if the values_source_list contains a commandline
source, this value is an alternative source for
actual command line arguments. Useful for testing or
preprocessing command line arguments.
use_auto_help - set to True if configman is to automatically set up
help output for command line invocations.
use_admin_controls - configman can add command line flags that it
interprets independently of the app defined
arguments. True enables this capability, while,
False supresses it.
quit_after_admin - if True and admin controls are enabled and used,
call sys.exit to end the app. This is useful to
stop the app from running if all that was done
was to write a config file or stop after help.
options_banned_from_help - a list of strings that will censor the
output of help to prevent specified
options from being listed in the help
output. This is useful for hiding debug
or secret command line arguments.
app_name - assigns a name to the app. This is used in help output
and as a default basename for config files.
app_version - assigns a version for the app used help output.
app_description - assigns a description for the app to be used in
the help output.
config_pathname - a hard coded path to the directory of or the full
path and name of the configuration file.
config_optional - a boolean indicating if a missing default config
file is optional. Note: this is only for the
default config file. If a config file is specified
on the commandline, it _must_ exist.
value_source_object_hook - a class used for the internal
representation of a value source.
This is used to enable any special
processing, like key translations.
"""
# instead of allowing mutables as default keyword argument values...
if definition_source is None:
definition_source_list = []
elif (
isinstance(definition_source, collections.Sequence) and
not isinstance(definition_source, basestring)
):
definition_source_list = list(definition_source)
else:
definition_source_list = [definition_source]
if argv_source is None:
self.argv_source = sys.argv[1:]
self.app_invocation_name = sys.argv[0]
else:
self.argv_source = argv_source
self.app_invocation_name = app_name
if options_banned_from_help is None:
options_banned_from_help = ['application']
self.config_pathname = config_pathname
self.config_optional = config_optional
self.value_source_object_hook = value_source_object_hook
self.app_name = app_name
self.app_version = app_version
self.app_description = app_description
self.args = [] # extra commandline arguments that are not switches
# will be stored here.
self._config = None # eventual container for DOM-like config object
self.option_definitions = Namespace()
self.definition_source_list = definition_source_list
if values_source_list is None:
# nothing set, assume defaults
if use_admin_controls:
values_source_list = (
cm.ConfigFileFutureProxy,
cm.environment,
cm.command_line
)
else:
values_source_list = (
cm.environment,
cm.command_line
)
admin_tasks_done = False
self.admin_controls_list = [
'help',
'admin.conf',
'admin.dump_conf',
'admin.print_conf',
'admin.strict'
]
self.options_banned_from_help = options_banned_from_help
if use_auto_help:
self._setup_auto_help()
if use_admin_controls:
admin_options = self._setup_admin_options(values_source_list)
self.definition_source_list.append(admin_options)
# iterate through the option definitions to create the nested dict
# hierarchy of all the options called 'option_definitions'
for a_definition_source in self.definition_source_list:
try:
safe_copy_of_def_source = a_definition_source.safe_copy()
except AttributeError:
# apparently, the definition source was not in the form of a
# Namespace object. This isn't a show stopper, but we don't
# know how to make a copy of this object safely: we know from
# experience that the stock copy.copy method leads to grief
# as many sub-objects within an option definition source can
# not be copied that way (classes, for example).
# The only action we can take is to trust and continue with the
# original copy of the definition source.
safe_copy_of_def_source = a_definition_source
def_sources.setup_definitions(
safe_copy_of_def_source,
self.option_definitions
)
if use_admin_controls:
# the name of the config file needs to be loaded from the command
# line prior to processing the rest of the command line options.
config_filename = \
value_sources.config_filename_from_commandline(self)
if (
config_filename
and cm.ConfigFileFutureProxy in values_source_list
):
self.option_definitions.admin.conf.default = config_filename
self.values_source_list = value_sources.wrap(
values_source_list,
self
)
known_keys = self._overlay_expand()
self._check_for_mismatches(known_keys)
# the app_name, app_version and app_description are to come from
# if 'application' option if it is present. If it is not present,
# get the app_name,et al, from parameters passed into the constructor.
# if those are empty, set app_name, et al, to empty strings
try:
app_option = self._get_option('application')
self.app_name = getattr(app_option.value, 'app_name', '')
self.app_version = getattr(app_option.value, 'app_version', '')
self.app_description = getattr(
app_option.value,
'app_description',
''
)
except exc.NotAnOptionError:
# there is no 'application' option, continue to use the
# 'app_name' from the parameters passed in, if they exist.
pass
if use_auto_help and self._get_option('help').value:
self.output_summary()
admin_tasks_done = True
if use_admin_controls and self._get_option('admin.print_conf').value:
self.print_conf()
admin_tasks_done = True
if use_admin_controls and self._get_option('admin.dump_conf').value:
self.dump_conf()
admin_tasks_done = True
if quit_after_admin and admin_tasks_done:
sys.exit()
#--------------------------------------------------------------------------
@contextlib.contextmanager
def context(self, mapping_class=DotDictWithAcquisition):
"""return a config as a context that calls close on every item when
it goes out of scope"""
config = None
try:
config = self.get_config(mapping_class=mapping_class)
yield config
finally:
if config:
self._walk_and_close(config)
#--------------------------------------------------------------------------
def get_config(self, mapping_class=DotDictWithAcquisition):
config = self._generate_config(mapping_class)
if self._aggregate(self.option_definitions, config, config):
# state changed, must regenerate
return self._generate_config(mapping_class)
else:
return config
#--------------------------------------------------------------------------
def output_summary(self,
output_stream=sys.stdout,
block_password=True):
"""outputs a usage tip and the list of acceptable commands.
This is useful as the output of the 'help' option.
parameters:
output_stream - an open file-like object suitable for use as the
target of a print statement
block_password - a boolean driving the use of a string of * in
place of the value for any object containing the
substring 'passowrd'
"""
if self.app_name or self.app_description:
print >> output_stream, 'Application:',
if self.app_name:
print >> output_stream, self.app_name, self.app_version
if self.app_description:
print >> output_stream, self.app_description
if self.app_name or self.app_description:
print >> output_stream, ''
names_list = self.get_option_names()
print >> output_stream, (
"usage:\n",
self.app_invocation_name,
"[OPTIONS]..."
),
bracket_count = 0
for key in names_list:
an_option = self.option_definitions[key]
if an_option.is_argument:
if an_option.default is None:
print >> output_stream, an_option.name,
else:
print >> output_stream, "[ %s" % an_option.name,
bracket_count += 1
print >> output_stream, ']' * bracket_count, '\n'
names_list.sort()
if names_list:
print >> output_stream, 'OPTIONS:'
pad = ' ' * 4
for name in names_list:
if name in self.options_banned_from_help:
continue
option = self._get_option(name)
line = ' ' * 2 # always start with 2 spaces
if option.short_form:
line += '-%s, ' % option.short_form
line += '--%s' % name
line += '\n'
doc = option.doc if option.doc is not None else ''
if doc:
line += '%s%s\n' % (pad, doc)
try:
value = option.value
type_of_value = type(value)
converter_function = conv.to_string_converters[type_of_value]
default = converter_function(value)
except KeyError:
default = option.value
if default is not None:
if 'password' in name.lower():
default = '*********'
if name not in ('help',):
# don't bother with certain dead obvious ones
line += '%s(default: %s)\n' % (pad, default)
print >> output_stream, line
#--------------------------------------------------------------------------
def print_conf(self):
"""write a config file to the pathname specified in the parameter. The
file extention determines the type of file written and must match a
registered type.
parameters:
config_pathname - the full path and filename of the target config
file."""
config_file_type = self._get_option('admin.print_conf').value
@contextlib.contextmanager
def stdout_opener():
yield sys.stdout
skip_keys = [
k for (k, v)
in self.option_definitions.iteritems()
if isinstance(v, Option) and v.exclude_from_print_conf
]
self.write_conf(config_file_type, stdout_opener, skip_keys=skip_keys)
#--------------------------------------------------------------------------
def dump_conf(self, config_pathname=None):
"""write a config file to the pathname specified in the parameter. The
file extention determines the type of file written and must match a
registered type.
parameters:
config_pathname - the full path and filename of the target config
file."""
if not config_pathname:
config_pathname = self._get_option('admin.dump_conf').value
opener = functools.partial(open, config_pathname, 'w')
config_file_type = os.path.splitext(config_pathname)[1][1:]
skip_keys = [
k for (k, v)
in self.option_definitions.iteritems()
if isinstance(v, Option) and v.exclude_from_dump_conf
]
self.write_conf(config_file_type, opener, skip_keys=skip_keys)
#--------------------------------------------------------------------------
def write_conf(self, config_file_type, opener, skip_keys=None):
"""write a configuration file to a file-like object.
parameters:
config_file_type - a string containing a registered file type OR
a for_XXX module from the value_source
package. Passing in an string that is
unregistered will result in a KeyError
opener - a callable object or function that returns a file like
object that works as a context in a with statement."""
blocked_keys = self.admin_controls_list
if skip_keys:
blocked_keys.extend(skip_keys)
if blocked_keys:
option_defs = self.option_definitions.safe_copy()
for a_blocked_key in blocked_keys:
try:
del option_defs[a_blocked_key]
except (AttributeError, KeyError):
# okay that key isn't here
pass
# remove empty namespaces
all_keys = [k for k in
option_defs.keys_breadth_first(include_dicts=True)]
for key in all_keys:
candidate = option_defs[key]
if (isinstance(candidate, Namespace) and not len(candidate)):
del option_defs[key]
else:
option_defs = self.option_definitions
value_sources.write(config_file_type,
option_defs,
opener)
#--------------------------------------------------------------------------
def log_config(self, logger):
"""write out the current configuration to a log-like object.
parameters:
logger - a object that implements a method called 'info' with the
same semantics as the call to 'logger.info'"""
logger.info("app_name: %s", self.app_name)
logger.info("app_version: %s", self.app_version)
logger.info("current configuration:")
config = [(key, self.option_definitions[key].value)
for key in self.option_definitions.keys_breadth_first()
if key not in self.admin_controls_list]
config.sort()
for key, val in config:
if 'password' in key.lower():
logger.info('%s: *********', key)
else:
try:
logger.info('%s: %s', key,
conv.to_string_converters[type(key)](val))
except KeyError:
logger.info('%s: %s', key, val)
#--------------------------------------------------------------------------
def get_option_names(self):
"""returns a list of fully qualified option names.
returns:
a list of strings representing the Options in the source Namespace
list. Each item will be fully qualified with dot delimited
Namespace names.
"""
return [x for x in self.option_definitions.keys_breadth_first()
if isinstance(self.option_definitions[x], Option)]
#--------------------------------------------------------------------------
def _create_reference_value_from_links(self, keys, known_keys):
"""this method steps through the option definitions looking for
alt paths. On finding one, it creates the 'reference_value_from' links
within the option definitions and populates it with copied options."""
# a set of known reference_value_from_links
set_of_reference_value_from_links = set()
for key in (k for k in keys if k not in known_keys):
an_option = self.option_definitions[key]
if an_option.reference_value_from:
reference_name = '.'.join((
an_option.reference_value_from,
an_option.name
))
if reference_name in self.option_definitions:
continue # this referenced value has already been defined
# no need to repeat it - skip on to the next key
reference_option = an_option.copy()
reference_option.reference_value_from = None
reference_option.name = reference_name
# wait, aren't we setting a fully qualified dotted name into
# the name field? Yes, 'add_option' below sees that
# full pathname and does the right thing with it to ensure
# that the reference_option is created within the
# correct namespace
set_of_reference_value_from_links.add(reference_option.name)
self.option_definitions.add_option(reference_option)
for a_reference_value_from in set_of_reference_value_from_links:
for x in range(a_reference_value_from.count('.')):
namespace_path = a_reference_value_from.rsplit('.', x + 1)[0]
self.option_definitions[namespace_path].ref_value_namespace()
return set_of_reference_value_from_links
#--------------------------------------------------------------------------
def _overlay_expand(self):
"""This method overlays each of the value sources onto the default
in each of the defined options. It does so using a breadth first
iteration, overlaying and expanding each level of the tree in turn.
As soon as no changes were made to any level, the loop breaks and the
work is done. The actual action of the overlay is to take the value
from the source and copy into the 'default' member of each Option
object.
"expansion" means converting an option value into its real type from
string. The conversion is accomplished by simply calling the
'set_value' method of the Option object. If the resultant type has its
own configuration options, bring those into the current namespace and
then proceed to overlay/expand those.
"""
new_keys_discovered = True # loop control, False breaks the loop
known_keys = set() # a set of keys that have been expanded
all_reference_values = {}
while new_keys_discovered: # loop until nothing more is done
# keys holds a list of all keys in the option definitons in
# breadth first order using this form: [ 'x', 'y', 'z', 'x.a',
# 'x.b', 'z.a', 'z.b', 'x.a.j', 'x.a.k', 'x.b.h']
keys = [
x for x
in self.option_definitions.keys_breadth_first()
if isinstance(self.option_definitions[x], Option)
]
new_keys_discovered = False # setup to break loop
# create alternate paths options
set_of_reference_value_from_links = \
self._create_reference_value_from_links(
keys,
known_keys
)
for a_ref_value_key in set_of_reference_value_from_links:
if a_ref_value_key not in all_reference_values:
all_reference_values[a_ref_value_key] = []
all_keys = list(set_of_reference_value_from_links) + keys
# overlay process:
# fetch all the default values from the value sources before
# applying the from string conversions
#
for key in (k for k in all_keys if k not in known_keys):
#if not isinstance(an_option, Option):
# continue # aggregations and other types are ignored
# loop through all the value sources looking for values
# that match this current key.
if self.option_definitions[key].reference_value_from:
reference_value_from = (
self.option_definitions[key].reference_value_from
)
top_key = key.split('.')[-1]
self.option_definitions[key].default = (
self.option_definitions[reference_value_from]
[top_key].default
)
all_reference_values[
'.'.join((reference_value_from, top_key))
].append(
key
)
for a_value_source in self.values_source_list:
try:
# get all the option values from this value source
val_src_dict = a_value_source.get_values(
self,
True,
self.value_source_object_hook
)
# get the Option for this key
opt = self.option_definitions[key]
# overlay the default with the new value from
# the value source. This assignment may come
# via acquisition, so the key given may not have
# been an exact match for what was returned.
opt.default = val_src_dict[key]
if key in all_reference_values:
# make sure that this value gets propagated to keys
# even if the keys have already been overlaid
known_keys -= set(all_reference_values[key])
except KeyError, x:
pass # okay, that source doesn't have this value
# expansion process:
# step through all the keys converting them to their proper
# types and bringing in any new keys in the process
for key in (k for k in all_keys if k not in known_keys):
# mark this key as having been seen and processed
known_keys.add(key)
an_option = self.option_definitions[key]
#if not isinstance(an_option, Option):
# continue # aggregations, namespaces are ignored
# apply the from string conversion to make the real value
an_option.set_value(an_option.default)
# new values have been seen, don't let loop break
new_keys_discovered = True
try:
try:
# try to fetch new requirements from this value
new_req = an_option.value.get_required_config()
except AttributeError:
new_req = an_option.value.required_config
# make sure what we got as new_req is actually a
# Mapping of some sort
if not isinstance(new_req, collections.Mapping):
# we didn't get a mapping, perhaps the option value
# was a Mock object - in any case we can't try to
# interpret 'new_req' as a configman requirement
# collection. We must abandon processing this
# option further
continue
# get the parent namespace
current_namespace = self.option_definitions.parent(key)
if current_namespace is None:
# we're at the top level, use the base namespace
current_namespace = self.option_definitions
if current_namespace._reference_value_from:
# don't expand things that are in reference value
# namespaces, they will be populated by expanding the
# targets
continue
# some new Options to be brought in may have already been
# seen and in the known_keys set. They must be marked
# as unseen so that the new default doesn't overwrite any
# of the overlays that have already taken place.
known_keys = known_keys.difference(
known_keys.intersection(new_req.keys())
)
# add the new Options to the namespace
new_namespace = new_req.safe_copy(
an_option.reference_value_from
)
for new_key in new_namespace.keys_breadth_first():
if new_key not in current_namespace:
current_namespace[new_key] = new_namespace[new_key]
except AttributeError, x:
# there are apparently no new Options to bring in from
# this option's value
pass
