Python config parsing helper for click

click-config provides a decorator that takes a python object and overwrites its attributes with values passed into the program via command line arguments.

Usage:

Create an entry point for your project (e.g: main.py):

from __future__ import print_function
import click
import click_config


class config(object):
    class logger(object):
        level = 'INFO'

    class mysql(object):
        host = 'localhost'


@click.command()
@click_config.wrap(module=config, sections=('logger', 'mysql'))
def main():
    print('log level: {}, mysql host: {}'.format(
        config.logger.level,
        config.mysql.host
    ))


if __name__ == '__main__':
    main()

$ python main.py --help
Usage: main.py [OPTIONS]

Options:
  --conf-mysql TEXT
  --conf-logger TEXT
  -c, --conf PATH
  --help              Show this message and exit.

The click_config.wrap decorator creates options for each one of the sections:

$ python main.py --conf-logger "level: WARN"
log level: WARN, mysql host: localhost

You can also use the --conf option to pass in yaml files:

$ echo "logger: {level: WARN}" > /tmp/logger.yaml
$ echo "mysql: {host: remotehost}" > /tmp/mysql.yaml
$ python main.py --conf /tmp/mysql.yaml --conf /tmp/logger.yaml
log level: WARN, mysql host: remotehost

You can also use conf.d style configurations and pass --conf to recursively traverse a directory

$ echo "logger: {level: WARN}" > /tmp/conf.d/logger.yaml
$ echo "mysql: {host: remotehost}" > /tmp/conf.d/mysql.yaml
$ python main.py --conf /tmp/conf.d
log level: WARN, mysql host: remotehost

Finally, you can use the CONF environment variable as an alternative to the --conf command line option, use ':' as the delimiter:

$ echo "logger: {level: WARN}" > /tmp/logger.yaml
$ echo "mysql: {host: remotehost}" > /tmp/mysql.yaml
$ CONF=/tmp/mysql.yaml:/tmp/logger.yaml python main.py
log level: WARN, mysql host: remotehost

inotify support (ALPHA):

click-config also supports watching files using inotify and tornado. To enable this feature you must install click-config with the inotify extra.

$ pip install 'click-config[inotify]'

To watch files simply invoke click_config.wrap() with watch=True The configuration module will automatically be updated when the files change. When using this feature, the wrapped function will receive a watcher parameter which you can use to listen for key change events.

def on_key_change(section, key, value):
    pass

@click.command()
@click_config.wrap(module=config, sections=('logger', 'mysql'), watch=True)
def main(watcher):
    watcher.add_listener(('mysql', 'host'), on_key_change)  # watch a specific key
    watcher.add_listener(('mysql', ), on_key_change)        # watch all keys in the 'mysql' section
    watcher.add_listener(watcher.ALL, on_key_change)        # watch all keys in all sections
    watcher.io_loop.start()

NOTES:

• click-config will parse any file ending with .conf, .ini, .yml or .yaml.
• .conf and .ini are loaded with ConfigParser
• .yml and .yaml are loaded with a yaml parser
• A configuration object must be modeled in a 2 level hierarchy like an .ini file, where keys are stored under a section.