!env

The !env Atmos YAML function is used to retrieve environment variables and assign them to the sections in Atmos stack manifests.

Usage

The !env function can be called with either one or two parameters:

  # Get the value of an environment variable.
  # If the environment variable is not present in the environment, `null` will be assigned
  !env <env-var-name>

  # Get the value of an environment variable.
  # If the environment variable is not present in the environment, the `default-value` will be assigned
  !env <env-var-name> <default-value>

Arguments

env-var-name

Environment variable name

default-value

(Optional) Default value to use if the environment variable is not present in the environment

If the function is called with one argument (the name of the environment variable), and the environment variable is not present, null will be assigned to the corresponding section in the Atmos manifest.

If the function is called with two arguments (the name of the environment variable and the default value), and the environment variable is not present, the default value will be assigned to the corresponding section in the Atmos manifest.

Examples

vars:
  # `api_key` will be set to `null` if the environment variable `API_KEY` is not present in the environment
  api_key: !env API_KEY
  # `app_name` will be set to the default value `my-app` if the environment variable `APP_NAME` is not present in the environment
  app_name: !env APP_NAME my-app

settings:
  # `provisioned_by_user` will be set to `null` if the environment variable `ATMOS_USER` is not present in the environment
  provisioned_by_user: !env ATMOS_USER

Handling default values with spaces

If you need to provide default values with spaces, enclose them in double quotes and use single quotes around the whole expression.

For example:

  # `app_name` will be set to the default value `my app` if the environment variable `APP_NAME` is not present in the environment
  app_name: !env 'APP_NAME "my app"'

  # `app_description` will be set to the default value `my app description` if the environment variable `APP_DESCRIPTION` is not present in the environment
  app_description: !env 'APP_DESCRIPTION "my app description"'

Handling Nested Quotes

If your default value contains both single and double quotes, wrap the entire function call in single quotes while keeping any required double quotes inside the expression:

# Use single quotes to wrap expressions containing double quotes
config_path: !env 'CONFIG_PATH "/etc/app/config.json"'

# Keep default values with mixed quotes readable by surrounding the expression with single quotes
api_endpoint: !env 'API_URL "https://api.example.com/v1"'

tip

Detailed escaping guidance (including bracket-notation examples) lives in the !terraform.output documentation. The same rules apply to !env because all YAML functions share the parser.

tip

You can use Atmos Stack Manifest Templating in the environment variable names and default values when calling the !env YAML function. Atmos processes the templates first, and then executes the !env function, allowing you to provide the parameters to the function dynamically.