gen3config

Handle YAML configurations with a given default/expected configuration. Library will overlay a provided configration over the default and ignore unknown values.

Quickstart

Example config-default.yaml for your application:

---
SOME_VALUE: 'default'

EXAMPLE:
    nested:
        key: 'value'
        is_boolean: true

Example config.py in your application:

from gen3config import Config

class AppConfig(Config):
    def __init__(self, *args, **kwargs):
        super(AppConfig, self).__init__(*args, **kwargs)

    def post_process(self):
        # do custom stuff here after parsing config
        pass

default_cfg_path = os.path.join(
    os.path.dirname(os.path.abspath(__file__)), "config-default.yaml"
)

config = AppConfig(default_cfg_path)

Now we want to get a specific configuration.

Example file ~/path/to/app-config.yaml:

SOME_VALUE: 'app-specific configuration'

EXAMPLE:
    nested:
        is_boolean: true

Example initialization function in your application:

from app.config import config

config.load('~/path/to/app-config.yaml')

Then from other files:

from app.config import config

print(config["SOME_VALUE"])  # 'app-specific configuration'
print(config["EXAMPLE"]["nested"]["key"])  # 'value'

NOTE: config["EXAMPLE"]["nested"]["key"] does not exist in the provided configuration, but it does exist in the default configuration. Therefore, the default value, 'value' is retrieved.

Details:

• Create a config-default.yaml and config.py in the top-level folder your app
• Inside config-default.yaml add keys and reasonable default values
• Inside config.py, create a class that inherits from this Config class
  • See above example
• Add a final line to your config.py that instantiates your custom class:
  • Ensure that you provide the default config path
    • If placed in same directory as config.py you can use something like:

      default_cfg_path = os.path.join(
          os.path.dirname(os.path.abspath(__file__)), "config-default.yaml"
      )
      config = FenceConfig(default_cfg_path)
      

• Import your instaniated object whenever you need to get configuration
  • Example: from fence.config import config
• Load in application configuration during init of your app
  • Example: config.load('path/to/fence-config.yaml')
• Now you can safely access anything that was in your config-default.yaml from this object as if it were a dictionary
  • Example: storage_creds = config["STORAGE_CREDENTIALS"]
  • Example: if config["SOME_BOOLEAN"]: ...
  • Example: nested_value = config["TOP_LEVEL"]["nested"]
• And of course you can import that into any file you want and will have access to keys/values
  • Example: from fence.config import config