nr.config 0.2.0

Utility library to implement composable YAML configuration files.

Note: This package is in the dangerous land of 0.x.y versions and may be subject to breaking changes with minor version increments.

nr.config

The nr.config package helps with configuration file processing and dynamic reloading tasks. It can serve as a generic library or give you a fast and easy framework.

Quickstart

The nr.config.process_config() function is the main function for processing config data. It expects the data to process as well as a number of processor plugins that will run over config. A common pattern is to use a conf section to hydrate variables for the remainder of the configuration.

from nr.config import process_config
from nr.config.plugins import Vars
import yaml

with open('var/conf/runtime.yaml') as fp:
  data = yaml.safe_load(fp)

config = process_config(data['runtime'], Vars({'conf': data['conf']}))

This particular example allows the use of references in the runtime block.

conf:
  value: 42
runtime:
  answer: '{{conf.value}}'

Service applications may want to reload the configuration file whenever it changes. For this purpose the nr.config module provides the ConfigReloadTask that uses the watchdog module to observe file changes and reload the config when the file changes. Errors that occur during the reload are automatically logged and the last valid configuration will be returned.

from nr.config.reloader import ConfigReloadTask
from nr.proxy import Proxy

reload_task = ConfigReloadTask('var/conf/runtime.yaml', load_config_from_file)
reload_task.reload_callback(callback)
reload_task.start()
config = Proxy(reload_task.get)

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Copyright © 2020 Niklas Rosenstein