Simple YAML to ENV Conversion

Converting YAML to ENV format is a common task when preparing configuration for applications that read environment variables. A flat YAML file maps directly to ENV key-value pairs with minimal transformation.

A simple YAML configuration:

database_host: localhost
database_port: 5432
database_name: myapp
debug: true
log_level: info

Converts to this .env file:

DATABASE_HOST=localhost
DATABASE_PORT=5432
DATABASE_NAME=myapp
DEBUG=true
LOG_LEVEL=info

Key transformation rules:

1. Keys are uppercased. ENV variable names conventionally use UPPER_SNAKE_CASE. YAML keys like database_host become DATABASE_HOST.
2. No quotes around simple values. Unlike YAML where strings can be quoted or unquoted, ENV files typically omit quotes for simple values without spaces.
3. Equals sign separates key and value. YAML uses : (colon-space), while ENV uses = with no spaces around it.
4. No indentation or nesting. ENV files are strictly flat -- one key-value pair per line.

Data type handling:

• Booleans (true/false) are kept as literal strings in ENV files. The consuming application decides how to parse them.
• Numbers remain as-is: 5432 stays 5432.
• Null values in YAML typically become empty strings: DATABASE_PASSWORD=.

Important considerations:

• ENV files do not support comments inline after values in all parsers (some support # comments).
• Values containing spaces, special characters, or # should be quoted: APP_NAME="My Application".
• There is no standard for ENV files -- behavior varies between tools (Docker, dotenv, systemd).

The conversion is straightforward for flat YAML structures, but becomes more complex when nested keys are involved.