3 """Global configuration driven by commandline arguments, environment variables
4 and saved configuration files. This works across several modules.
12 parser = config.add_commandline_args(
14 "Args related to module doing the thing.",
17 "--module_do_the_thing",
20 help="Should the module do the thing?"
28 parser = config.add_commandline_args(
30 "A program that does the thing.",
36 help="Should we really do the thing?"
38 config.parse() # Very important, this must be invoked!
40 If you set this up and remember to invoke config.parse(), all commandline
41 arguments will play nicely together. This is done automatically for you
42 if you're using the bootstrap module's initialize wrapper.
46 [--module_do_the_thing MODULE_DO_THE_THING]
50 Args related to module doing the thing.
52 --module_do_the_thing MODULE_DO_THE_THING
53 Should the module do the thing?
56 A program that does the thing
59 Should we really do the thing?
61 Arguments themselves should be accessed via
62 config.config['arg_name']. e.g.
64 if not config.config['dry_run']:
74 from typing import Any, Dict, List, Optional
76 # This module is commonly used by others in here and should avoid
77 # taking any unnecessary dependencies back on them.
79 # Defer logging messages until later when logging has been initialized.
80 saved_messages: List[str] = []
82 # Make a copy of the original program arguments.
83 program_name = os.path.basename(sys.argv[0])
84 original_argv = [arg for arg in sys.argv]
87 # A global parser that we will collect arguments into.
88 args = argparse.ArgumentParser(
90 formatter_class=argparse.ArgumentDefaultsHelpFormatter,
91 fromfile_prefix_chars="@",
92 epilog=f'{program_name} uses config.py ({__file__}) for global, cross-module configuration setup and parsing.',
95 # Keep track of if we've been called and prevent being called more
97 config_parse_called = False
100 # A global configuration dictionary that will contain parsed arguments.
101 # It is also this variable that modules use to access parsed arguments.
102 # This is the data that is most interesting to our callers; it will hold
103 # the configuration result.
105 # It would be really nice if this shit worked from interactive python
108 def add_commandline_args(title: str, description: str = ""):
109 """Create a new context for arguments and return a handle."""
110 return args.add_argument_group(title, description)
113 group = add_commandline_args(
114 f'Global Config ({__file__})',
115 'Args that control the global config itself; how meta!',
121 help='Config file (populated via --config_savefile) from which to read args in lieu or in addition to commandline.',
127 help='Display the global configuration (possibly derived from multiple sources) on STDERR at program startup.',
134 help='Populate config file compatible with --config_loadfile to save global config for later use.',
137 '--config_rejects_unrecognized_arguments',
141 'If present, config will raise an exception if it doesn\'t recognize an argument. The '
142 + 'default behavior is to ignore this so as to allow interoperability with programs that '
143 + 'want to use their own argparse calls to parse their own, separate commandline args.'
148 def is_flag_already_in_argv(var: str):
149 """Is a particular flag passed on the commandline?"""
156 def parse(entry_module: Optional[str]) -> Dict[str, Any]:
157 """Main program should call this early in main(). Note that the
158 bootstrap.initialize wrapper takes care of this automatically.
161 global config_parse_called
162 if config_parse_called:
165 global saved_messages
167 # If we're about to do the usage message dump, put the main module's
168 # argument group last in the list (if possible) so that when the user
169 # passes -h or --help, it will be visible on the screen w/o scrolling.
170 reordered_action_groups = []
173 if arg == '--help' or arg == '-h':
174 for group in args._action_groups:
175 if entry_module is not None and entry_module in group.title:
176 reordered_action_groups.append(group)
177 elif program_name in group.title:
178 reordered_action_groups.append(group)
180 reordered_action_groups.insert(0, group)
181 args._action_groups = reordered_action_groups
183 # Examine the environment for variables that match known flags.
184 # For a flag called --example_flag the corresponding environment
185 # variable would be called EXAMPLE_FLAG.
186 usage_message = args.format_usage()
189 for x in usage_message.split():
203 # Environment vars the same as flag names without
204 # the initial -'s and in UPPERCASE.
205 env = var.strip('-').upper()
206 if env in os.environ:
207 if not is_flag_already_in_argv(var):
208 value = os.environ[env]
209 saved_messages.append(
210 f'Initialized from environment: {var} = {value}'
212 from string_utils import to_bool
214 if len(chunks) == 1 and to_bool(value):
216 elif len(chunks) > 1:
218 sys.argv.append(value)
224 # Look for loadfile and read/parse it if present.
226 saw_other_args = False
227 grab_next_arg = False
228 for arg in sys.argv[1:]:
229 if 'config_loadfile' in arg:
230 pieces = arg.split('=')
238 saw_other_args = True
240 if loadfile is not None:
242 msg = f'Augmenting commandline arguments with those from {loadfile}.'
243 print(msg, file=sys.stderr)
244 saved_messages.append(msg)
245 if not os.path.exists(loadfile):
247 f'ERROR: --config_loadfile argument must be a file, {loadfile} not found.',
251 with open(loadfile, 'r') as rf:
252 newargs = rf.readlines()
253 newargs = [arg.strip('\n') for arg in newargs if 'config_savefile' not in arg]
256 # Parse (possibly augmented, possibly completely overwritten)
257 # commandline args with argparse normally and populate config.
258 known, unknown = args.parse_known_args()
259 config.update(vars(known))
261 # Reconstruct the argv with unrecognized flags for the benefit of
262 # future argument parsers. For example, unittest_main in python
263 # has some of its own flags. If we didn't recognize it, maybe
266 if config['config_rejects_unrecognized_arguments']:
268 f'Encountered unrecognized config argument(s) {unknown} with --config_rejects_unrecognized_arguments enabled; halting.'
270 saved_messages.append(
271 f'Config encountered unrecognized commandline arguments: {unknown}'
273 sys.argv = sys.argv[:1] + unknown
275 # Check for savefile and populate it if requested.
276 savefile = config['config_savefile']
277 if savefile and len(savefile) > 0:
278 with open(savefile, 'w') as wf:
279 wf.write("\n".join(original_argv[1:]))
281 # Also dump the config on stderr if requested.
282 if config['config_dump']:
285 config_parse_called = True
289 def has_been_parsed() -> bool:
290 """Has the global config been parsed yet?"""
291 global config_parse_called
292 return config_parse_called
296 """Print the current config to stdout."""
297 print("Global Configuration:", file=sys.stderr)
298 pprint.pprint(config, stream=sys.stderr)
303 """Log messages saved earlier now that logging has been initialized."""
304 logger = logging.getLogger(__name__)
305 global saved_messages
306 for _ in saved_messages: