# encoding: utf-8 """A base class for a configurable application.""" # Copyright (c) IPython Development Team. # Distributed under the terms of the Modified BSD License. from __future__ import print_function from copy import deepcopy import json import logging import os import re import sys from collections import defaultdict, OrderedDict from decorator import decorator from traitlets.config.configurable import Configurable, SingletonConfigurable from traitlets.config.loader import ( KVArgParseConfigLoader, PyFileConfigLoader, Config, ArgumentError, ConfigFileNotFound, JSONFileConfigLoader ) from traitlets.traitlets import ( Bool, Unicode, List, Enum, Dict, Instance, TraitError, observe, observe_compat, default, ) from ipython_genutils.importstring import import_item from ipython_genutils.text import indent, wrap_paragraphs, dedent from ipython_genutils import py3compat import six #----------------------------------------------------------------------------- # Descriptions for the various sections #----------------------------------------------------------------------------- # merge flags&aliases into options option_description = """ Arguments that take values are actually convenience aliases to full Configurables, whose aliases are listed on the help line. For more information on full configurables, see '--help-all'. """.strip() # trim newlines of front and back keyvalue_description = """ Parameters are set from command-line arguments of the form: `--Class.trait=value`. This line is evaluated in Python, so simple expressions are allowed, e.g.:: `--C.a='range(3)'` For setting C.a=[0,1,2]. """.strip() # trim newlines of front and back # sys.argv can be missing, for example when python is embedded. See the docs # for details: http://docs.python.org/2/c-api/intro.html#embedding-python if not hasattr(sys, "argv"): sys.argv = [""] subcommand_description = """ Subcommands are launched as `{app} cmd [args]`. For information on using subcommand 'cmd', do: `{app} cmd -h`. """ # get running program name #----------------------------------------------------------------------------- # Application class #----------------------------------------------------------------------------- _envvar = os.environ.get('TRAITLETS_APPLICATION_RAISE_CONFIG_FILE_ERROR','') if _envvar.lower() in {'1','true'}: TRAITLETS_APPLICATION_RAISE_CONFIG_FILE_ERROR = True elif _envvar.lower() in {'0','false',''} : TRAITLETS_APPLICATION_RAISE_CONFIG_FILE_ERROR = False else: raise ValueError("Unsupported value for environment variable: 'TRAITLETS_APPLICATION_RAISE_CONFIG_FILE_ERROR' is set to '%s' which is none of {'0', '1', 'false', 'true', ''}."% _envvar ) @decorator def catch_config_error(method, app, *args, **kwargs): """Method decorator for catching invalid config (Trait/ArgumentErrors) during init. On a TraitError (generally caused by bad config), this will print the trait's message, and exit the app. For use on init methods, to prevent invoking excepthook on invalid input. """ try: return method(app, *args, **kwargs) except (TraitError, ArgumentError) as e: app.print_help() app.log.fatal("Bad config encountered during initialization:") app.log.fatal(str(e)) app.log.debug("Config at the time: %s", app.config) app.exit(1) class ApplicationError(Exception): pass class LevelFormatter(logging.Formatter): """Formatter with additional `highlevel` record This field is empty if log level is less than highlevel_limit, otherwise it is formatted with self.highlevel_format. Useful for adding 'WARNING' to warning messages, without adding 'INFO' to info, etc. """ highlevel_limit = logging.WARN highlevel_format = " %(levelname)s |" def format(self, record): if record.levelno >= self.highlevel_limit: record.highlevel = self.highlevel_format % record.__dict__ else: record.highlevel = "" return super(LevelFormatter, self).format(record) class Application(SingletonConfigurable): """A singleton application with full configuration support.""" # The name of the application, will usually match the name of the command # line application name = Unicode(u'application') # The description of the application that is printed at the beginning # of the help. description = Unicode(u'This is an application.') # default section descriptions option_description = Unicode(option_description) keyvalue_description = Unicode(keyvalue_description) subcommand_description = Unicode(subcommand_description) python_config_loader_class = PyFileConfigLoader json_config_loader_class = JSONFileConfigLoader # The usage and example string that goes at the end of the help string. examples = Unicode() # A sequence of Configurable subclasses whose config=True attributes will # be exposed at the command line. classes = [] def _classes_inc_parents(self): """Iterate through configurable classes, including configurable parents Children should always be after parents, and each class should only be yielded once. """ seen = set() for c in self.classes: # We want to sort parents before children, so we reverse the MRO for parent in reversed(c.mro()): if issubclass(parent, Configurable) and (parent not in seen): seen.add(parent) yield parent # The version string of this application. version = Unicode(u'0.0') # the argv used to initialize the application argv = List() # Whether failing to load config files should prevent startup raise_config_file_errors = Bool(TRAITLETS_APPLICATION_RAISE_CONFIG_FILE_ERROR) # The log level for the application log_level = Enum((0,10,20,30,40,50,'DEBUG','INFO','WARN','ERROR','CRITICAL'), default_value=logging.WARN, help="Set the log level by value or name.").tag(config=True) @observe('log_level') @observe_compat def _log_level_changed(self, change): """Adjust the log level when log_level is set.""" new = change.new if isinstance(new, six.string_types): new = getattr(logging, new) self.log_level = new self.log.setLevel(new) _log_formatter_cls = LevelFormatter log_datefmt = Unicode("%Y-%m-%d %H:%M:%S", help="The date format used by logging formatters for %(asctime)s" ).tag(config=True) log_format = Unicode("[%(name)s]%(highlevel)s %(message)s", help="The Logging format template", ).tag(config=True) @observe('log_datefmt', 'log_format') @observe_compat def _log_format_changed(self, change): """Change the log formatter when log_format is set.""" _log_handler = self.log.handlers[0] _log_formatter = self._log_formatter_cls(fmt=self.log_format, datefmt=self.log_datefmt) _log_handler.setFormatter(_log_formatter) @default('log') def _log_default(self): """Start logging for this application. The default is to log to stderr using a StreamHandler, if no default handler already exists. The log level starts at logging.WARN, but this can be adjusted by setting the ``log_level`` attribute. """ log = logging.getLogger(self.__class__.__name__) log.setLevel(self.log_level) log.propagate = False _log = log # copied from Logger.hasHandlers() (new in Python 3.2) while _log: if _log.handlers: return log if not _log.propagate: break else: _log = _log.parent if sys.executable and sys.executable.endswith('pythonw.exe'): # this should really go to a file, but file-logging is only # hooked up in parallel applications _log_handler = logging.StreamHandler(open(os.devnull, 'w')) else: _log_handler = logging.StreamHandler() _log_formatter = self._log_formatter_cls(fmt=self.log_format, datefmt=self.log_datefmt) _log_handler.setFormatter(_log_formatter) log.addHandler(_log_handler) return log # the alias map for configurables aliases = Dict({'log-level' : 'Application.log_level'}) # flags for loading Configurables or store_const style flags # flags are loaded from this dict by '--key' flags # this must be a dict of two-tuples, the first element being the Config/dict # and the second being the help string for the flag flags = Dict() @observe('flags') @observe_compat def _flags_changed(self, change): """ensure flags dict is valid""" new = change.new for key, value in new.items(): assert len(value) == 2, "Bad flag: %r:%s" % (key, value) assert isinstance(value[0], (dict, Config)), "Bad flag: %r:%s" % (key, value) assert isinstance(value[1], six.string_types), "Bad flag: %r:%s" % (key, value) # subcommands for launching other applications # if this is not empty, this will be a parent Application # this must be a dict of two-tuples, # the first element being the application class/import string # and the second being the help string for the subcommand subcommands = Dict() # parse_command_line will initialize a subapp, if requested subapp = Instance('traitlets.config.application.Application', allow_none=True) # extra command-line arguments that don't set config values extra_args = List(Unicode()) cli_config = Instance(Config, (), {}, help="""The subset of our configuration that came from the command-line We re-load this configuration after loading config files, to ensure that it maintains highest priority. """ ) _loaded_config_files = List() def __init__(self, **kwargs): SingletonConfigurable.__init__(self, **kwargs) # Ensure my class is in self.classes, so my attributes appear in command line # options and config files. cls = self.__class__ if cls not in self.classes: if self.classes is cls.classes: # class attr, assign instead of insert cls.classes = [cls] + self.classes else: self.classes.insert(0, self.__class__) @observe('config') @observe_compat def _config_changed(self, change): super(Application, self)._config_changed(change) self.log.debug('Config changed:') self.log.debug(repr(change.new)) @catch_config_error def initialize(self, argv=None): """Do the basic steps to configure me. Override in subclasses. """ self.parse_command_line(argv) def start(self): """Start the app mainloop. Override in subclasses. """ if self.subapp is not None: return self.subapp.start() def print_alias_help(self): """Print the alias part of the help.""" if not self.aliases: return lines = [] classdict = {} for cls in self.classes: # include all parents (up to, but excluding Configurable) in available names for c in cls.mro()[:-3]: classdict[c.__name__] = c for alias, longname in self.aliases.items(): classname, traitname = longname.split('.',1) cls = classdict[classname] trait = cls.class_traits(config=True)[traitname] help = cls.class_get_trait_help(trait).splitlines() # reformat first line help[0] = help[0].replace(longname, alias) + ' (%s)'%longname if len(alias) == 1: help[0] = help[0].replace('--%s='%alias, '-%s '%alias) lines.extend(help) # lines.append('') print(os.linesep.join(lines)) def print_flag_help(self): """Print the flag part of the help.""" if not self.flags: return lines = [] for m, (cfg,help) in self.flags.items(): prefix = '--' if len(m) > 1 else '-' lines.append(prefix+m) lines.append(indent(dedent(help.strip()))) # lines.append('') print(os.linesep.join(lines)) def print_options(self): if not self.flags and not self.aliases: return lines = ['Options'] lines.append('-'*len(lines[0])) lines.append('') for p in wrap_paragraphs(self.option_description): lines.append(p) lines.append('') print(os.linesep.join(lines)) self.print_flag_help() self.print_alias_help() print() def print_subcommands(self): """Print the subcommand part of the help.""" if not self.subcommands: return lines = ["Subcommands"] lines.append('-'*len(lines[0])) lines.append('') for p in wrap_paragraphs(self.subcommand_description.format( app=self.name)): lines.append(p) lines.append('') for subc, (cls, help) in self.subcommands.items(): lines.append(subc) if help: lines.append(indent(dedent(help.strip()))) lines.append('') print(os.linesep.join(lines)) def print_help(self, classes=False): """Print the help for each Configurable class in self.classes. If classes=False (the default), only flags and aliases are printed. """ self.print_description() self.print_subcommands() self.print_options() if classes: help_classes = self.classes if help_classes: print("Class parameters") print("----------------") print() for p in wrap_paragraphs(self.keyvalue_description): print(p) print() for cls in help_classes: cls.class_print_help() print() else: print("To see all available configurables, use `--help-all`") print() self.print_examples() def document_config_options(self): """Generate rST format documentation for the config options this application Returns a multiline string. """ return '\n'.join(c.class_config_rst_doc() for c in self._classes_inc_parents()) def print_description(self): """Print the application description.""" for p in wrap_paragraphs(self.description): print(p) print() def print_examples(self): """Print usage and examples. This usage string goes at the end of the command line help string and should contain examples of the application's usage. """ if self.examples: print("Examples") print("--------") print() print(indent(dedent(self.examples.strip()))) print() def print_version(self): """Print the version string.""" print(self.version) @catch_config_error def initialize_subcommand(self, subc, argv=None): """Initialize a subcommand with argv.""" subapp,help = self.subcommands.get(subc) if isinstance(subapp, six.string_types): subapp = import_item(subapp) # clear existing instances self.__class__.clear_instance() # instantiate self.subapp = subapp.instance(parent=self) # and initialize subapp self.subapp.initialize(argv) def flatten_flags(self): """flatten flags and aliases, so cl-args override as expected. This prevents issues such as an alias pointing to InteractiveShell, but a config file setting the same trait in TerminalInteraciveShell getting inappropriate priority over the command-line arg. Only aliases with exactly one descendent in the class list will be promoted. """ # build a tree of classes in our list that inherit from a particular # it will be a dict by parent classname of classes in our list # that are descendents mro_tree = defaultdict(list) for cls in self.classes: clsname = cls.__name__ for parent in cls.mro()[1:-3]: # exclude cls itself and Configurable,HasTraits,object mro_tree[parent.__name__].append(clsname) # flatten aliases, which have the form: # { 'alias' : 'Class.trait' } aliases = {} for alias, cls_trait in self.aliases.items(): cls,trait = cls_trait.split('.',1) children = mro_tree[cls] if len(children) == 1: # exactly one descendent, promote alias cls = children[0] aliases[alias] = '.'.join([cls,trait]) # flatten flags, which are of the form: # { 'key' : ({'Cls' : {'trait' : value}}, 'help')} flags = {} for key, (flagdict, help) in self.flags.items(): newflag = {} for cls, subdict in flagdict.items(): children = mro_tree[cls] # exactly one descendent, promote flag section if len(children) == 1: cls = children[0] newflag[cls] = subdict flags[key] = (newflag, help) return flags, aliases @catch_config_error def parse_command_line(self, argv=None): """Parse the command line arguments.""" argv = sys.argv[1:] if argv is None else argv self.argv = [ py3compat.cast_unicode(arg) for arg in argv ] if argv and argv[0] == 'help': # turn `ipython help notebook` into `ipython notebook -h` argv = argv[1:] + ['-h'] if self.subcommands and len(argv) > 0: # we have subcommands, and one may have been specified subc, subargv = argv[0], argv[1:] if re.match(r'^\w(\-?\w)*$', subc) and subc in self.subcommands: # it's a subcommand, and *not* a flag or class parameter return self.initialize_subcommand(subc, subargv) # Arguments after a '--' argument are for the script IPython may be # about to run, not IPython iteslf. For arguments parsed here (help and # version), we want to only search the arguments up to the first # occurrence of '--', which we're calling interpreted_argv. try: interpreted_argv = argv[:argv.index('--')] except ValueError: interpreted_argv = argv if any(x in interpreted_argv for x in ('-h', '--help-all', '--help')): self.print_help('--help-all' in interpreted_argv) self.exit(0) if '--version' in interpreted_argv or '-V' in interpreted_argv: self.print_version() self.exit(0) # flatten flags&aliases, so cl-args get appropriate priority: flags,aliases = self.flatten_flags() loader = KVArgParseConfigLoader(argv=argv, aliases=aliases, flags=flags, log=self.log) self.cli_config = deepcopy(loader.load_config()) self.update_config(self.cli_config) # store unparsed args in extra_args self.extra_args = loader.extra_args @classmethod def _load_config_files(cls, basefilename, path=None, log=None, raise_config_file_errors=False): """Load config files (py,json) by filename and path. yield each config object in turn. """ if not isinstance(path, list): path = [path] for path in path[::-1]: # path list is in descending priority order, so load files backwards: pyloader = cls.python_config_loader_class(basefilename+'.py', path=path, log=log) if log: log.debug("Looking for %s in %s", basefilename, path or os.getcwd()) jsonloader = cls.json_config_loader_class(basefilename+'.json', path=path, log=log) loaded = [] filenames = [] for loader in [pyloader, jsonloader]: config = None try: config = loader.load_config() except ConfigFileNotFound: pass except Exception: # try to get the full filename, but it will be empty in the # unlikely event that the error raised before filefind finished filename = loader.full_filename or basefilename # problem while running the file if raise_config_file_errors: raise if log: log.error("Exception while loading config file %s", filename, exc_info=True) else: if log: log.debug("Loaded config file: %s", loader.full_filename) if config: for filename, earlier_config in zip(filenames, loaded): collisions = earlier_config.collisions(config) if collisions and log: log.warning("Collisions detected in {0} and {1} config files." " {1} has higher priority: {2}".format( filename, loader.full_filename, json.dumps(collisions, indent=2), )) yield (config, loader.full_filename) loaded.append(config) filenames.append(loader.full_filename) @property def loaded_config_files(self): """Currently loaded configuration files""" return self._loaded_config_files[:] @catch_config_error def load_config_file(self, filename, path=None): """Load config files by filename and path.""" filename, ext = os.path.splitext(filename) new_config = Config() for (config, filename) in self._load_config_files(filename, path=path, log=self.log, raise_config_file_errors=self.raise_config_file_errors, ): new_config.merge(config) if filename not in self._loaded_config_files: # only add to list of loaded files if not previously loaded self._loaded_config_files.append(filename) # add self.cli_config to preserve CLI config priority new_config.merge(self.cli_config) self.update_config(new_config) def _classes_in_config_sample(self): """ Yields only classes with own traits, and their subclasses. Thus, produced sample config-file will contain all classes on which a trait-value may be overridden: - either on the class owning the trait, - or on its subclasses, even if those subclasses do not define any traits themselves. """ cls_to_config = OrderedDict( (cls, bool(cls.class_own_traits(config=True))) for cls in self._classes_inc_parents()) def is_any_parent_included(cls): return any(b in cls_to_config and cls_to_config[b] for b in cls.__bases__) ## Mark "empty" classes for inclusion if their parents own-traits, # and loop until no more classes gets marked. # while True: to_incl_orig = cls_to_config.copy() cls_to_config = OrderedDict( (cls, inc_yes or is_any_parent_included(cls)) for cls, inc_yes in cls_to_config.items()) if cls_to_config == to_incl_orig: break for cl, inc_yes in cls_to_config.items(): if inc_yes: yield cl def generate_config_file(self): """generate default config file from Configurables""" lines = ["# Configuration file for %s." % self.name] lines.append('') for cls in self._classes_in_config_sample(): lines.append(cls.class_config_section()) return '\n'.join(lines) def exit(self, exit_status=0): self.log.debug("Exiting application: %s" % self.name) sys.exit(exit_status) @classmethod def launch_instance(cls, argv=None, **kwargs): """Launch a global instance of this Application If a global instance already exists, this reinitializes and starts it """ app = cls.instance(**kwargs) app.initialize(argv) app.start() #----------------------------------------------------------------------------- # utility functions, for convenience #----------------------------------------------------------------------------- def boolean_flag(name, configurable, set_help='', unset_help=''): """Helper for building basic --trait, --no-trait flags. Parameters ---------- name : str The name of the flag. configurable : str The 'Class.trait' string of the trait to be set/unset with the flag set_help : unicode help string for --name flag unset_help : unicode help string for --no-name flag Returns ------- cfg : dict A dict with two keys: 'name', and 'no-name', for setting and unsetting the trait, respectively. """ # default helpstrings set_help = set_help or "set %s=True"%configurable unset_help = unset_help or "set %s=False"%configurable cls,trait = configurable.split('.') setter = {cls : {trait : True}} unsetter = {cls : {trait : False}} return {name : (setter, set_help), 'no-'+name : (unsetter, unset_help)} def get_config(): """Get the config object for the global Application instance, if there is one otherwise return an empty config object """ if Application.initialized(): return Application.instance().config else: return Config()