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'------------------------------------------------------------------------------\n{program_name} uses config.py ({__file__}) for global, cross-module configuration setup and parsing.\n------------------------------------------------------------------------------'
95 # Keep track of if we've been called and prevent being called more
97 config_parse_called = False
99 # A global configuration dictionary that will contain parsed arguments.
100 # It is also this variable that modules use to access parsed arguments.
101 # This is the data that is most interesting to our callers; it will hold
102 # the configuration result.
103 config: Dict[str, Any] = {}
106 def add_commandline_args(title: str, description: str = ""):
107 """Create a new context for arguments and return a handle."""
108 return args.add_argument_group(title, description)
111 group = add_commandline_args(
112 f'Global Config ({__file__})',
113 'Args that control the global config itself; how meta!',
119 help='Config file (populated via --config_savefile) from which to read args in lieu or in addition to commandline.',
125 help='Display the global configuration (possibly derived from multiple sources) on STDERR at program startup.',
132 help='Populate config file compatible with --config_loadfile to save global config for later use.',
136 def is_flag_already_in_argv(var: str):
137 """Is a particular flag passed on the commandline?"""
144 def parse(entry_module: Optional[str]) -> Dict[str, Any]:
145 """Main program should call this early in main(). Note that the
146 bootstrap.initialize wrapper takes care of this automatically.
149 global config_parse_called
150 if config_parse_called:
153 global saved_messages
155 # If we're about to do the usage message dump, put the main module's
156 # argument group last in the list (if possible) so that when the user
157 # passes -h or --help, it will be visible on the screen w/o scrolling.
158 reordered_action_groups = []
161 if arg == '--help' or arg == '-h':
162 for group in args._action_groups:
163 if entry_module is not None and entry_module in group.title:
164 reordered_action_groups.append(group)
165 elif program_name in group.title:
166 reordered_action_groups.append(group)
168 reordered_action_groups.insert(0, group)
169 args._action_groups = reordered_action_groups
171 # Examine the environment for variables that match known flags.
172 # For a flag called --example_flag the corresponding environment
173 # variable would be called EXAMPLE_FLAG.
174 usage_message = args.format_usage()
177 for x in usage_message.split():
191 # Environment vars the same as flag names without
192 # the initial -'s and in UPPERCASE.
193 env = var.strip('-').upper()
194 if env in os.environ:
195 if not is_flag_already_in_argv(var):
196 value = os.environ[env]
197 saved_messages.append(
198 f'Initialized from environment: {var} = {value}'
200 from string_utils import to_bool
201 if len(chunks) == 1 and to_bool(value):
203 elif len(chunks) > 1:
205 sys.argv.append(value)
211 # Look for loadfile and read/parse it if present.
213 saw_other_args = False
214 grab_next_arg = False
215 for arg in sys.argv[1:]:
216 if 'config_loadfile' in arg:
217 pieces = arg.split('=')
225 saw_other_args = True
227 if loadfile is not None:
229 msg = f'Augmenting commandline arguments with those from {loadfile}.'
230 print(msg, file=sys.stderr)
231 saved_messages.append(msg)
232 if not os.path.exists(loadfile):
233 print(f'ERROR: --config_loadfile argument must be a file, {loadfile} not found.',
236 with open(loadfile, 'r') as rf:
237 newargs = rf.readlines()
238 newargs = [arg.strip('\n') for arg in newargs if 'config_savefile' not in arg]
241 # Parse (possibly augmented, possibly completely overwritten)
242 # commandline args with argparse normally and populate config.
243 known, unknown = args.parse_known_args()
244 config.update(vars(known))
246 # Reconstruct the argv with unrecognized flags for the benefit of
247 # future argument parsers. For example, unittest_main in python
248 # has some of its own flags. If we didn't recognize it, maybe
250 sys.argv = sys.argv[:1] + unknown
252 # Check for savefile and populate it if requested.
253 savefile = config['config_savefile']
254 if savefile and len(savefile) > 0:
255 with open(savefile, 'w') as wf:
257 "\n".join(original_argv[1:])
260 # Also dump the config on stderr if requested.
261 if config['config_dump']:
264 config_parse_called = True
268 def has_been_parsed() -> bool:
269 """Has the global config been parsed yet?"""
270 global config_parse_called
271 return config_parse_called
275 """Print the current config to stdout."""
276 print("Global Configuration:", file=sys.stderr)
277 pprint.pprint(config, stream=sys.stderr)
282 """Log messages saved earlier now that logging has been initialized."""
283 logger = logging.getLogger(__name__)
284 global saved_messages
285 for _ in saved_messages: