3 # © Copyright 2021-2022, Scott Gasch
5 """Global configuration driven by commandline arguments, environment variables,
6 saved configuration files, and zookeeper-based dynamic configurations. This
7 works across several modules.
15 parser = config.add_commandline_args(
17 "Args related to module doing the thing.",
20 "--module_do_the_thing",
23 help="Should the module do the thing?"
30 parser = config.add_commandline_args(
32 "A program that does the thing.",
38 help="Should we really do the thing?"
42 config.parse() # Very important, this must be invoked!
44 If you set this up and remember to invoke config.parse(), all commandline
45 arguments will play nicely together. This is done automatically for you
46 if you're using the :meth:`bootstrap.initialize` decorator on
47 your program's entry point. See :meth:`python_modules.bootstrap.initialize`
56 if __name__ == '__main__':
59 Either way, you'll get this behavior from the commandline::
63 [--module_do_the_thing MODULE_DO_THE_THING]
67 Args related to module doing the thing.
69 --module_do_the_thing MODULE_DO_THE_THING
70 Should the module do the thing?
73 A program that does the thing
76 Should we really do the thing?
78 Arguments themselves should be accessed via
79 :code:`config.config['arg_name']`. e.g.::
81 if not config.config['dry_run']:
91 from typing import Any, Dict, List, Optional, Tuple
93 from kazoo.client import KazooClient
94 from kazoo.protocol.states import WatchedEvent
98 # This module is commonly used by others in here and should avoid
99 # taking any unnecessary dependencies back on them.
101 # Make a copy of the original program arguments immediately upon module load.
102 PROGRAM_NAME: str = os.path.basename(sys.argv[0])
103 ORIG_ARGV: List[str] = sys.argv.copy()
106 class OptionalRawFormatter(argparse.HelpFormatter):
107 """This formatter has the same bahavior as the normal argparse text
108 formatter except when the help text of an argument begins with
109 "RAW|". In that case, the line breaks are preserved and the text
112 Use this, for example, when you need the helptext of an argument
113 to have its spacing preserved exactly, e.g.::
119 choices=['CHEAT', 'AUTOPLAY', 'SELFTEST', 'PRECOMPUTE', 'PLAY'],
121 help='''RAW|Our mode of operation. One of:
123 PLAY = play wordle with me! Pick a random solution or
124 specify a solution with --template.
126 CHEAT = given a --template and, optionally, --letters_in_word
127 and/or --letters_to_avoid, return the best guess word;
129 AUTOPLAY = given a complete word in --template, guess it step
130 by step showing work;
132 SELFTEST = autoplay every possible solution keeping track of
133 wins/losses and average number of guesses;
135 PRECOMPUTE = populate hash table with optimal guesses.
140 def _split_lines(self, text, width):
141 if text.startswith('RAW|'):
142 return text[4:].splitlines()
143 return argparse.HelpFormatter._split_lines(self, text, width)
146 # A global argparser that we will collect arguments in. Each module (including
147 # us) will add arguments to a separate argument group.
148 ARGS = argparse.ArgumentParser(
150 formatter_class=OptionalRawFormatter,
151 fromfile_prefix_chars="@",
152 epilog=f'{PROGRAM_NAME} uses config.py ({__file__}) for global, cross-module configuration setup and parsing.',
153 # I don't fully understand why but when loaded by sphinx sometimes
154 # the same module is loaded many times causing any arguments it
155 # registers via module-level code to be redefined. Work around
156 # this iff the program is 'sphinx-build'
157 conflict_handler='resolve' if PROGRAM_NAME == 'sphinx-build' else 'error',
160 # Arguments specific to config.py. Other users should get their own group by
161 # invoking config.add_commandline_args.
162 GROUP = ARGS.add_argument_group(
163 f'Global Config ({__file__})',
164 'Args that control the global config itself; how meta!',
170 help='Config file (populated via --config_savefile) from which to read args in lieu or in addition to those passed via the commandline. Note that if the given path begins with "zk:" then it is interpreted as a zookeeper path instead of as a filesystem path. When loading config from zookeeper, any argument with the string "dynamic" in the name (e.g. --module_dynamic_url) may be modified at runtime by changes made to zookeeper (using --config_savefile=zk:path). You should therefore either write your code to handle dynamic argument changes or avoid naming arguments "dynamic" if you use zookeeper configuration paths.',
176 help='Display the global configuration (possibly derived from multiple sources) on STDERR at program startup time.',
183 help='Populate a config file (compatible with --config_loadfile) with the given path for later use. If the given path begins with "zk:" it is interpreted as a zookeeper path instead of a filesystem path. When updating zookeeper-based configs, all running programs that read their configuration from zookeeper (via --config_loadfile=zk:path) at startup time will see their configuration dynamically updated; flags with "dynamic" in their names (e.g. --my_dynamic_flag) may have their values changed. You should therefore either write your code to handle dynamic argument changes or avoid naming arguments "dynamic" if you use zookeeper configuration paths.',
186 '--config_rejects_unrecognized_arguments',
189 help='If present, config will raise an exception if it doesn\'t recognize an argument. The default behavior is to ignore unknown arguments so as to allow interoperability with programs that want to use their own argparse calls to parse their own, separate commandline args.',
195 Everything in the config module used to be module-level functions and
196 variables but it made the code ugly and harder to maintain. Now, this
197 class does the heavy lifting. We still rely on some globals, though:
199 ARGS and GROUP to interface with argparse
200 PROGRAM_NAME stores argv[0] close to program invocation
201 ORIG_ARGV stores the original argv list close to program invocation
202 CONFIG and config: hold the (singleton) instance of this class.
207 # Has our parse() method been invoked yet?
208 self.config_parse_called = False
210 # A configuration dictionary that will contain parsed
211 # arguments. This is the data that is most interesting to our
212 # callers as it will hold the configuration result.
213 self.config: Dict[str, Any] = {}
215 # Defer logging messages until later when logging has been
217 self.saved_messages: List[str] = []
219 # A zookeeper client that is lazily created so as to not incur
220 # the latency of connecting to zookeeper for programs that are
221 # not reading or writing their config data into zookeeper.
222 self.zk: Optional[KazooClient] = None
224 # Per known zk file, what is the max version we have seen?
225 self.max_version: Dict[str, int] = {}
227 def __getitem__(self, key: str) -> Optional[Any]:
228 """If someone uses []'s on us, pass it onto self.config."""
229 return self.config.get(key, None)
231 def __setitem__(self, key: str, value: Any) -> None:
232 self.config[key] = value
234 def __contains__(self, key: str) -> bool:
235 return key in self.config
238 def add_commandline_args(title: str, description: str = "") -> argparse._ArgumentGroup:
239 """Create a new context for arguments and return a handle.
242 title: A title for your module's commandline arguments group.
243 description: A helpful description of your module.
246 An argparse._ArgumentGroup to be populated by the caller.
248 return ARGS.add_argument_group(title, description)
251 def overwrite_argparse_epilog(msg: str) -> None:
252 """Allows your code to override the default epilog created by
256 msg: The epilog message to substitute for the default.
261 def is_flag_already_in_argv(var: str) -> bool:
262 """Returns true if a particular flag is passed on the commandline
266 var: The flag to search for.
274 def print_usage() -> None:
275 """Prints the normal help usage message out."""
282 program usage help text as a string.
284 return ARGS.format_usage()
287 def _reorder_arg_action_groups_before_help(entry_module: Optional[str]):
288 """Internal. Used to reorder the arguments before dumping out a
289 generated help string such that the main program's arguments come
293 reordered_action_groups = []
294 for grp in ARGS._action_groups:
295 if entry_module is not None and entry_module in grp.title: # type: ignore
296 reordered_action_groups.append(grp)
297 elif PROGRAM_NAME in GROUP.title: # type: ignore
298 reordered_action_groups.append(grp)
300 reordered_action_groups.insert(0, grp)
301 return reordered_action_groups
304 def _parse_arg_into_env(arg: str) -> Optional[Tuple[str, str, List[str]]]:
305 """Internal helper to parse commandling args into environment vars."""
307 if not arg.startswith('['):
310 if not arg.endswith(']'):
320 # Environment vars the same as flag names without
321 # the initial -'s and in UPPERCASE.
325 return var, env, chunks
327 def _augment_sys_argv_from_environment_variables(self):
328 """Internal. Look at the system environment for variables that match
329 commandline arg names. This is done via some munging such that:
331 :code:`--argument_to_match`
335 :code:`ARGUMENT_TO_MATCH`
337 This allows users to set args via shell environment variables
338 in lieu of passing them on the cmdline.
341 usage_message = Config.usage()
345 # Foreach valid optional commandline option (chunk) generate
346 # its analogous environment variable.
347 for chunk in usage_message.split():
354 _ = Config._parse_arg_into_env(arg)
357 if env in os.environ:
358 if not Config.is_flag_already_in_argv(var):
359 value = os.environ[env]
360 self.saved_messages.append(
361 f'Initialized from environment: {var} = {value}'
363 from string_utils import to_bool
365 if len(chunks) == 1 and to_bool(value):
367 elif len(chunks) > 1:
369 sys.argv.append(value)
372 def _process_dynamic_args(self, event: WatchedEvent):
374 logger = logging.getLogger(__name__)
375 contents, meta = self.zk.get(event.path, watch=self._process_dynamic_args)
376 logger.debug('Update for %s at version=%d.', event.path, meta.version)
378 'Max known version for %s is %d.', event.path, self.max_version.get(event.path, 0)
380 if meta.version > self.max_version.get(event.path, 0):
381 self.max_version[event.path] = meta.version
382 contents = contents.decode()
384 for arg in contents.split():
386 temp_argv.append(arg)
387 logger.info("Updating %s from zookeeper async config change.", arg)
388 if len(temp_argv) > 0:
391 known, _ = ARGS.parse_known_args()
393 self.config.update(vars(known))
395 def _augment_sys_argv_from_loadfile(self):
396 """Internal. Augment with arguments persisted in a saved file."""
399 saw_other_args = False
400 grab_next_arg = False
401 for arg in sys.argv[1:]:
402 if 'config_loadfile' in arg:
403 pieces = arg.split('=')
411 saw_other_args = True
413 if loadfile is not None:
415 if loadfile[:3] == 'zk:':
418 self.zk = KazooClient(
419 hosts=scott_secrets.ZOOKEEPER_NODES,
422 keyfile=scott_secrets.ZOOKEEPER_CLIENT_CERT,
423 keyfile_password=scott_secrets.ZOOKEEPER_CLIENT_PASS,
424 certfile=scott_secrets.ZOOKEEPER_CLIENT_CERT,
427 zkpath = loadfile[3:]
428 if not zkpath.startswith('/config/'):
429 zkpath = '/config/' + zkpath
430 zkpath = re.sub(r'//+', '/', zkpath)
431 if not self.zk.exists(zkpath):
433 f'ERROR: --config_loadfile argument must be a file, {loadfile} not found (in zookeeper)'
435 except Exception as e:
437 f'ERROR: Error talking with zookeeper while looking for {loadfile}'
439 elif not os.path.exists(loadfile):
441 f'ERROR: --config_loadfile argument must be a file, {loadfile} not found.'
445 msg = f'Augmenting commandline arguments with those from {loadfile}.'
447 msg = f'Reading commandline arguments from {loadfile}.'
448 print(msg, file=sys.stderr)
449 self.saved_messages.append(msg)
455 contents, meta = self.zk.get(zkpath, watch=self._process_dynamic_args)
456 contents = contents.decode()
459 for arg in contents.split('\n')
460 if 'config_savefile' not in arg
462 self.saved_messages.append(f'Setting {zkpath}\'s max_version to {meta.version}')
463 self.max_version[zkpath] = meta.version
464 except Exception as e:
465 raise Exception(f'Error reading {zkpath} from zookeeper.') from e
466 self.saved_messages.append(f'Loaded config from zookeeper from {zkpath}')
468 with open(loadfile, 'r') as rf:
469 newargs = rf.readlines()
470 newargs = [arg.strip('\n') for arg in newargs if 'config_savefile' not in arg]
473 def dump_config(self):
474 """Print the current config to stdout."""
475 print("Global Configuration:", file=sys.stderr)
476 pprint.pprint(self.config, stream=sys.stderr)
479 def parse(self, entry_module: Optional[str]) -> Dict[str, Any]:
480 """Main program should call this early in main(). Note that the
481 :code:`bootstrap.initialize` wrapper takes care of this automatically.
482 This should only be called once per program invocation.
485 if self.config_parse_called:
488 # If we're about to do the usage message dump, put the main
489 # module's argument group last in the list (if possible) so that
490 # when the user passes -h or --help, it will be visible on the
491 # screen w/o scrolling.
493 if arg in ('--help', '-h'):
494 if entry_module is not None:
495 entry_module = os.path.basename(entry_module)
496 ARGS._action_groups = Config._reorder_arg_action_groups_before_help(entry_module)
498 # Examine the environment for variables that match known flags.
499 # For a flag called --example_flag the corresponding environment
500 # variable would be called EXAMPLE_FLAG. If found, hackily add
501 # these into sys.argv to be parsed.
502 self._augment_sys_argv_from_environment_variables()
504 # Look for loadfile and read/parse it if present. This also
505 # works by jamming these values onto sys.argv.
506 self._augment_sys_argv_from_loadfile()
508 # Parse (possibly augmented, possibly completely overwritten)
509 # commandline args with argparse normally and populate config.
510 known, unknown = ARGS.parse_known_args()
511 self.config.update(vars(known))
513 # Reconstruct the argv with unrecognized flags for the benefit of
514 # future argument parsers. For example, unittest_main in python
515 # has some of its own flags. If we didn't recognize it, maybe
518 if config['config_rejects_unrecognized_arguments']:
520 f'Encountered unrecognized config argument(s) {unknown} with --config_rejects_unrecognized_arguments enabled; halting.'
522 self.saved_messages.append(
523 f'Config encountered unrecognized commandline arguments: {unknown}'
525 sys.argv = sys.argv[:1] + unknown
527 # Check for savefile and populate it if requested.
528 savefile = config['config_savefile']
529 if savefile and len(savefile) > 0:
530 data = '\n'.join(ORIG_ARGV[1:])
531 if savefile[:3] == 'zk:':
532 zkpath = savefile[3:]
533 if not zkpath.startswith('/config/'):
534 zkpath = '/config/' + zkpath
535 zkpath = re.sub(r'//+', '/', zkpath)
538 self.zk = KazooClient(
539 hosts=scott_secrets.ZOOKEEPER_NODES,
542 keyfile=scott_secrets.ZOOKEEPER_CLIENT_CERT,
543 keyfile_password=scott_secrets.ZOOKEEPER_CLIENT_PASS,
544 certfile=scott_secrets.ZOOKEEPER_CLIENT_CERT,
548 if len(data) > 1024 * 1024:
549 raise Exception(f'Saved args are too large! ({len(data)} bytes)')
550 if not self.zk.exists(zkpath):
551 self.zk.create(zkpath, data)
552 self.saved_messages.append(
553 f'Just created {zkpath}; setting its max_version to 0'
555 self.max_version[zkpath] = 0
557 meta = self.zk.set(zkpath, data)
558 self.saved_messages.append(
559 f'Setting {zkpath}\'s max_version to {meta.version}'
561 self.max_version[zkpath] = meta.version
562 except Exception as e:
563 raise Exception(f'Failed to create zookeeper path {zkpath}') from e
564 self.saved_messages.append(f'Saved config to zookeeper in {zkpath}')
566 with open(savefile, 'w') as wf:
569 # Also dump the config on stderr if requested.
570 if config['config_dump']:
573 self.config_parse_called = True
576 def has_been_parsed(self) -> bool:
577 """Returns True iff the global config has already been parsed"""
578 return self.config_parse_called
580 def late_logging(self):
581 """Log messages saved earlier now that logging has been initialized."""
582 logger = logging.getLogger(__name__)
583 logger.debug('Original commandline was: %s', ORIG_ARGV)
584 for _ in self.saved_messages:
588 # A global singleton instance of the Config class.
591 # A lot of client code uses config.config['whatever'] to lookup
592 # configuration so to preserve this we make this, config.config, with
593 # a __getitem__ method on it.
596 # Config didn't use to be a class; it was a mess of module-level
597 # functions and data. The functions below preserve the old interface
598 # so that existing clients do not need to be changed. As you can see,
599 # they mostly just thunk into the config class.
602 def add_commandline_args(title: str, description: str = "") -> argparse._ArgumentGroup:
603 """Create a new context for arguments and return a handle. An alias
604 for config.config.add_commandline_args.
607 title: A title for your module's commandline arguments group.
608 description: A helpful description of your module.
611 An argparse._ArgumentGroup to be populated by the caller.
613 return CONFIG.add_commandline_args(title, description)
616 def parse(entry_module: Optional[str]) -> Dict[str, Any]:
617 """Main program should call this early in main(). Note that the
618 :code:`bootstrap.initialize` wrapper takes care of this automatically.
619 This should only be called once per program invocation. Subsequent
620 calls do not reparse the configuration settings but rather just
621 return the current state.
623 return CONFIG.parse(entry_module)
626 def has_been_parsed() -> bool:
627 """Returns True iff the global config has already been parsed"""
628 return CONFIG.has_been_parsed()
631 def late_logging() -> None:
632 """Log messages saved earlier now that logging has been initialized."""
633 CONFIG.late_logging()
636 def dump_config() -> None:
637 """Print the current config to stdout."""
641 def overwrite_argparse_epilog(msg: str) -> None:
642 """Allows your code to override the default epilog created by
646 msg: The epilog message to substitute for the default.
648 Config.overwrite_argparse_epilog(msg)
651 def is_flag_already_in_argv(var: str) -> bool:
652 """Returns true if a particular flag is passed on the commandline
656 var: The flag to search for.
658 return Config.is_flag_already_in_argv(var)
661 def print_usage() -> None:
662 """Prints the normal help usage message out."""
669 program usage help text as a string.
671 return Config.usage()