structured-config 1.2

Configuration module for python where the config structure is solely defined in python with full autocomplete support.

A configuration module for python where the config structure is solely defined in python.

There are lots of different modules and formats available for creating configuration files in a python project.

All of the ones I’ve used in the past have one main limitations in common however; the primary definition of the configuration elements it either not written in python, or it’s written in something like a python dict where you don’t get particularly good static inspection of elements.

I personally like to do my python development in a smart ide like pycharm where I can take full advantage of inspection and auto-completion. If you config is not written in python however, I don’t get to do this.

If you want any kind of introspection of config files, you end up having some kind of python parser of the config file with all the configuration elements repeated in both the default template and in some kind of mirror class.

This module aims to remove this limitation.

Now, your config.py file in your project can be something like .. code-block:

from structured_config import ConfigFile, Structure

class config(Structure):

    class server(Structure):
        url = 'https:www.example.com'
        username = '<user>'
        password = '<password>'


    # Max number of tcp connections at any one time
    concurrent_connections =  32

    # Local service port
    service_port = 45080


config_file = ConfigFile('./config.yaml', config)

Config = config_file.config  # type: config

Any other modules in your project can then simply .. code-block:

from config import Config

import requests
from requests.auth import HTTPBasicAuth


r = requests.get(Config.server.url, auth=HTTPBasicAuth(Config.server.username, Config.server.password))

and so on. Your IDE should give you full autocomplete on all these elements, becuase as far as it known your config is a normal class with normal static attributes.

If you want to change these config items in code it’s as simple as setting the attribute .. code-block:

from config import Config

Config.concurrent_connections = 64

That’s it. The config is written to disk in the yaml file pointed to in ConfigFile()

The yaml file can be manually changed on disk of course. At this stage it’ll require a restart of the app to reload the file however .. code-block:

!config
server: !server
  password: <password>
  url: https:www.example.com
  username: <user>
concurrent_connections: 32
service_port: 45080

If you want a slightly more complex config file with a list of elements, this can be handed too .. code-block:

import structured_config
from structured_config import Structure, ConfigFile

# Pre-define the object we want to store a list of.
class Map(Structure):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.remote_path = kwargs.get('remote_path', '')
        self.local_path = kwargs.get('local_path', '')


# Default configuration for the application
class config(Structure):

    class server(Structure):
        url = 'https:www.example.com'
        username = '<user>'
        password = '<password>'

    mapping = [
        Map(
            remote_path="/test/",
            local_path="~/test/"
        ),
        Map(
            remote_path="/one/",
            local_path="~/two/"
        ),
        Map(
            remote_path="/two/",
            local_path="~/one/"
        )
    ]

config_file = ConfigFile('config.yaml', config)
Config = config_file.config  # type: config

Your main code can access the Map items in the list by all the normal means. if you append() new ones onto the list or pop() old ones off the list, the config will automatically write them to disk. Same goes for editing either of the attributes in any of the Map objects that have been added to the list.

If you want to enforce the type of some attributes, we’ve got that covered as well .. code-block:

from structured_config import ConfigFile, Structure, TypedField, IntField

class config(Structure):

    concurrent_connections = IntField(32)

    path = TypedField('$HOME', os.path.expandvars)


config_file = ConfigFile('./config.yaml', config)

Config = config_file.config  # type: config

Currently there’s the int() enforcement type, anf a generic enforcement field where you can pass your own converter/validater function.

Any time a config attribute is set, it will be passed through the validation function first.

Get’s on the attribute return the raw value, not the high level Field object.