Environment Variables

Environment variables can be used in place of defining values in your configuration file directly. This may be useful to you, if you:

• want to make your configuration more dynamic,
• want to define some variables in your compose.yaml file,
• want to hide sensitive information (although secrets might be a better fit).

The main downside of environment variables is that you can only define scalar values in YAML. Lists and maps are not supported¹.

Syntax

!env_var ENV_VAR_NAME default_value

• ENV_VAR_NAME is the name of the environment variable to substitute in, on configuration parse. It is case-sensitive.
• default_value is optional, allowing you define a fallback value, in case ENV_VAR_NAME is undefined or empty.

Example

Given this sample environment:

RADARR_BASE_URL="http://localhost:7878"
RADARR_API_KEY="5aec487a70b5417e880d3923e4786d18"

A configuration file like this:

radarr:
  default:
    base_url: !env_var RADARR_BASE_URL
    api_key: !env_var RADARR_API_KEY

would effectively be replaced with:

radarr:
  default:
    base_url: http://localhost:7878
    api_key: 5aec487a70b5417e880d3923e4786d18

Footnotes

1. You can still use environment variables within lists, but it cannot stand in place of the entire list. ↩