yaml-config-tags 0.4.0

Custom tags to extend YAML for managing advanced configurations easily within a file. Environment variables, includes, and jinja templating.

yaml-config-tags

Provides a set of custom tags to extend YAML for managing advanced configurations easily within a file. It supports:

• Environment variables: !env
• File includes: !include
• Jinja templating: !jinja

Installation

pip install yaml-config-tags

Usage

Simply load the configuration file using config_load and pass a context dictionary to the loader.

config_load(
    path: str | Path,
    context: dict[str, Any] | None = None,
    jinja_settings: dict[str, Any] | None = None,
    jinja_filters: dict[str, Callable] | None = None,
) -> Any

Example

from yaml_config import config_load

context = {
    'name': 'John Doe'
}
config = config_load('config.yml', context)

# config.yml
database:
  user: !env DB_USER
  password: !env DB_PASSWORD

advanced: !include advanced.yaml

greeting: !jinja |
  Hello, {{ name }}!

Features

Environment Variables

You can use environment variables in your configuration file by using the !env tag.

There are three ways to use environment variables:

• !env VAR_NAME - Load the environment variable VAR_NAME. If it is not set, an exception will be raised.
• !env [VAR_NAME, default_value] - Load the environment variable VAR_NAME with a default value if it is not set.
• !env [VAR_NAME, FALLBACK_VAR1, .., FALLBACK_VARn, default_value] - Load the environment variable VAR_NAME, if it is not set, try to load the fallback variables in order. If none of them are set, use the default value.

Explicit type

Environment variables are converted using implicit yaml types by default, but you can force a specific data type with tag suffix:

• !env:str VAR_NAME
• !env:int VAR_NAME

Valid type suffix are:

• str
• int
• float
• bool
• timestamp

You can also combine defaults and fallbacks with type suffix: !env:str [VAR_NAME, default_value]

Includes

You can include other files in your configuration file by using the !include tag.

# config.yml
advanced: !include advanced.yaml

Three types of files are supported, specified as a tag suffix:

• yaml - Load the file as a YAML file.
• json - Load the file as a JSON file.
• txt - Load the file as a plain text file.

If no suffix is specified, the file will be loaded as a YAML file.

text_data: !include:txt text.txt
json_data: !include:json data.json

Relative paths are resolved relative to the directory of the file that contains the include.

Glob Patterns

You can use glob patterns in the file path, and all matching files will be included as a list.

files: !include:yaml "data/*.yaml"

Jinja Templating

You can use Jinja templating in your configuration file by using the !jinja tag. The context available to the template is passed as an argument to the loader.

greeting: !jinja |
  Hello, {{ name }}!

The !jinja tag is a short form for !jinja:str, a jinja template rendered as a string.

Native objects

In addition to plain text templates, you can also render a template to native objects.

connection:
  url: !env DB_URL
  token_provider: !jinja:obj |
    {{token_provider}}

When using !jinja:obj the template is rendered using NativeEnvironment and the result is evaluated as a native object instead of a string.