Python库 | stela-1.0.0a2.tar.gz

# Welcome to Stela [](https://github.com/chrismaille/stela/actions) [](https://www.python.org) [](https://conventionalcommits.org) <a href="https://github.com/psf/black"><img alt="Code style: black" src="https://img.shields.io/badge/code%20style-black-000000.svg"></a> [Stela](https://en.wikipedia.org/wiki/Stele) were the "configuration files" of ancient times. This library aims to simplify your project configurations, from *json*, *yaml*, *ini* or *toml* files in a single Python dictionary, which values can be easily be override by environment variables. ### Install ```shell $ pip install stela ``` ### Example You can use `.yaml`, `.ini`, `.json` and `.toml` files. Suppose a file called `development.ini` which contains: ```ini [foo] bar = value ``` Stela will convert data into a python dictionary: ```python { "foo": { "bar": "value" } } ``` And you can use the settings like this: ```python from stela import settings my_conf = settings["foo.bar"] # my_conf = "value" ``` This is possible because Stela uses under the hood the [Scalpl](https://github.com/ducdetronquito/scalpl) library. ### How Stela find the configuration files? By default, Stela will use the value from `ENVIRONMENT` environment variable to find correspondent INI file. For example, if you set `ENVIRONMENT=development` Stela will look for `development.ini` file in project root. You can change this behaviour inside `pyproject.toml` file: ```toml [tools.stela] environment_variable_name = "ENVIRONMENT" config_file_extension = "INI" # YAML, TOML, JSON config_file_prefix = "" # You can add a prefix before name - ex.: env_development.ini config_file_suffix = "" # You can add a suffix after name - ex.: development_v1.ini default_environment = "development" # use this if you do not want to define the ENVIRONMENT key config_file_path = "." # relative path from project root for configuration files ``` ### How Stela find the Environment Variables? When asked for a value, Stela will try to find a environment variable using the full uppercase slug path. For example, if key is `foo.bar`, Stela will search for a env called `FOO_BAR` before returning his dict value. Also, you can add a prefix/suffix in this calculated environment name (ex.: `MYPROJECT_FOO_BAR`). To do this, define them in `pyproject.toml`: ```toml [tools.stela] environment_prefix = "MYPROJECT_" environment_suffix = "" ``` In above case, Stela will look for the `MYPROJECT_FOO_BAR` env: ```python # FOO_BAR = "hello_world" or # MYPROJECT_FOO_BAR = "hello world" if you define environment_prefix from stela import settings my_conf = settings["foo.bar"] # my_conf = "hello world" ``` ### How Stela handle more complex cases? Stela uses this lifecycle to handle the settings load: ```text Pre-Load (optional) -> Load or Default Load > Post-Load (optional) ``` If you have more complex cases to retrieve your project settings (ex.: reading external services, load settings from database or parse from a different file format or library), you can use Stela decorators for `pre_load`, `load` and `post_load` phases: * If you use the `pre_load` decorator, data parsed in this phase will be passed to **Load** phase. * If you use the `load` decorator, it will be used instead the Stela's `default_loader`. The data returned here will update the dictionary received in previous phase * If you use the `post_load` decorator, data returned in this phase will update the dictionary received in previous phase. Only one function are allowed per phase. > These loaders need to return a valid Python dictionary. ##### Lifecycle example: ```python from stela.decorators import pre_load, load, post_load from typing import Dict, Any from stela import StelaOptions @pre_load def pre_load(options: StelaOptions) -> Dict[Any, Any]: # data value is: {} # Stela Options are available in options object. return {"foo": "bar"} @load def load(data: dict, options: StelaOptions) -> Dict[Any, Any]: # data value is: {"foo": "bar"} # Using load, default_loader will not be invoked return {"has_dogs": True} @post_load def post_load(data: dict, options: StelaOptions) -> Dict[Any, Any]: # data value is: {"foo": "bar", "has_dogs": True} return {"number_of_dogs": 1} # Final data is {"foo": "bar", "has_dogs": True, "number_of_dogs": 1} ``` ##### Post-Load SSM Example: ```python # stela_loader.py import boto3 from stela.decorators import post_load from stela import StelaOptions from typing import Dict, Any @post_load def add_ssm_parameters(data: dict, options: StelaOptions) -> Dict[Any, Any]: """Load settings from SSM to current Stela data. This loader will be called after Stela default loader. Data returned must be a Python Dictionary. :param data (dict): Data parsed from previous phases :param options (obj): Stela Options from pyproject.toml :return Dict[Any, Any] """ ssm = boto3.client('ssm') environment = options.current_environment parameters = ssm.get_parameters_by_path( Name=f'/foo/bar/{environment}', WithDecryption=True ) return parameters ``` ### When Stela read the data? Stela are imported once, at module level. This is the python equivalent for a Singleton object - project settings are load and immediately available: ```python from stela import settings from flask import Flask app = Flask(__name__) app.config.update( SECRET_KEY=settings["my_app.secret"] # will read from dict or MY_APP_SECRET value ) @app.route("/") def hello(): return f"Hello, Environment is {settings.stela_options.current_environment}" ``` If you need to reload settings, use the `stela.stela_reload` function: ```python from stela import stela_reload def test_different_environments(monkeypatch): from stela import settings assert settings.stela_options.current_environment == "test" monkeypatch.setenv("ENVIRONMENT", "production") settings = stela_reload() assert settings.stela_options.current_environment == "production" monkeypatch.delenv("ENVIRONMENT") ``` ### How Stela read the dictionary values? Stela will respect the file format limitations. For example, INI files always return values as string, TOML files returning datetime objects, etc... For environment variables, Stela will return value as string, by default. For example: `NUMBER_OF_CATS=3` will return a string. You can set Stela to literal evaluate these values, as per [ast.literal_eval](https://docs.python.org/3.7/library/ast.html?highlight=literal_eval#ast.literal_eval) rules. To do this, add in `pyproject.toml`: ```toml [tool.stela] evaluate_data = true ``` ### All Stela Configuration Options: All configuration files can be override using a environment variable, using the `STELA_` prefix. For example, `default_environment` turns `STELA_DEFAULT_ENVIRONMENT`. ```toml # All keys and default values available in pyproject.toml [tool.stela] environment_variable_name = "ENVIRONMENT" config_file_extension = "INI" # YAML, TOML, JSON config_file_prefix = "" # You can add a prefix before name - ex.: env_development.ini config_file_suffix = "" # You can add a suffix after name - ex.: development_v1.ini config_file_path = "." environment_prefix = "" # ex.: settings["foo.bar"'] looks for MY_PREFIX_FOO_BAR environment_suffix = "" # ex.: settings["foo.bar"'] looks for FOO_BAR_MY_SUFFIX default_environment = "" evaluate_data = false show_logs = true # as per loguru settings. ``` ### Not working? Dont panic. Get a towel and, please, open a [issue](https://github.com/chrismaille/stela/issues).