Dotenv Expand
dotenv-expand expands variable references in .env files so that $VAR or ${VAR} refer to the value of an already-defined variable.
Purpose
To support references between variables in .env files, avoiding duplicate definitions and keeping configuration consistent.
Mechanism
While parsing .env, $VAR and ${VAR} in values are replaced with the value of VAR already defined in the same file or in process.env. A default value is supported as ${VAR:-default}.
Use cases
- Environment variable reference expansion
- Composing Docker .env files
- CI/CD variable reuse