Dotenv Validator

This gem validates .env variables. You can configure validation rules by adding the appropriate comments to the .env.sample file.


Add the gem to your gemfile:

gem "dotenv_validator", github: "fastruby/dotenv_validator", branch: :main

Call DotenvValidator.check! in an initializer:

echo "DotenvValidator.check!" > "config/initializers/1_dotenv_validator.rb"

Note the 1_ in the name so it's executed before any other initializer, since initializers are run in alphabetical order.

You can use DotenvValidator.check without the ! to show warnings instead of raising an exception.


At the moment it is only available on Github, so you would need to run:

bundle update --source dotenv_validator

Configuring env variable

In your .env.sample file, you can add comments to tell DotenvValidator how to validate the variable:

MY_REQUIRED_VAR=value #required
THIS_IS_AN_OPTIONAL_INT=123 #format=int
THIS_IS_A_REQUIRED_EMAIL=123 #required,format=email


Regexp format

If you have a complex format, you can use a regexp for validation:

MY_WEIRD_ENV_VAR=123_ABC #required,format=\d{3}_\w{3}

In the above example, \d{3}_\w{3} is converted to a regexp and the value is checked against it.


Bug reports and pull requests are welcome on GitHub at This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

When Submitting a Pull Request:

  • If your PR closes any open GitHub issues, please include Closes #XXXX in your comment

  • Please include a summary of the change and which issue is fixed or which feature is introduced.

  • If changes to the behavior are made, clearly describe what changes.

  • If changes to the UI are made, please include screenshots of the before and after.