Envil

A NodeJS package for validating environment variables

Envil is a NodeJS package that allows you to validate environment variables defined in your .env file. It can help you ensure that all the variables your application needs are set before it starts.

Installation

npm install envil

Usage

import envil from 'envil';

const envs = ['NODE_ENV', 'PORT'];

envil(envs, {
  shouldExit: true,
  template: '%e is not set. Please set it in your .env file.',
});

Examples

Example 1: Checking for required environment variables

Suppose you have a NodeJS application that requires two environment variables, NODE_ENV and PORT. You can use Envil to check for the existence of these variables before starting your application:

import envil from 'envil';

const envs = ['NODE_ENV', 'PORT'];

envil(envs, {
  shouldExit: true,
});

If either of these variables is not set, Envil will print an error message and terminate the application with exit code 1.

Example 2: Using optional environment variables

You can also use Envil to check for optional environment variables. For example, suppose your application has a database but it can be used in a read-only mode if the DATABASE_URL environment variable is not set:

import envil from 'envil';

const envs = [
  {
    name: 'DATABASE_URL',
    optional: true,
  },
];

envil(envs, {
  shouldExit: false,
  template: '%e is not set. Using read-only mode.',
});

If the DATABASE_URL variable is not set, Envil will print a message indicating that the database will be used in read-only mode.

Options

Envil provides two optional options:

• shouldExit: (default: true) If this option is true, Envil will terminate the application with exit code 1 if any errors are encountered. If false, it will only print an error message and allow the application to continue running.
• template: (default: %e is not set. Please set it in your .env file.) You can use this option to customize the error message that Envil prints.

Use cases

Envil can be used for various purposes, including:

• Checking for the existence of environment variables required for your application
• Ensuring that environment variables have valid values
• Preventing your application from starting if environment variables are not set correctly

Contributing

Envil is an open-source project and you can contribute to its development by submitting pull requests.

License

Envil is released under the MIT license.

Further examples

Here are some further examples of how Envil can be used:

• Checking for a specific value for an environment variable:

import envil from 'envil';

const envs = [
  {
    name: 'NODE_ENV',
  },
];

envil(envs, {
  shouldExit: true,
});

• Checking for multiple environment variables with different options:

import envil from 'envil';

const envs = [
  {
    name: 'NODE_ENV',
    optional: true,
  },
  {
    name: 'PORT',
  },
];

envil(envs, {
  shouldExit: false,
  template: '%e is not set. Using default value of %v.',
});

• Using Envil with a custom logger:

import envil from 'envil';

const logger = (message: string) => {
  console.error(message);
};

envil(['NODE_ENV', 'PORT'], {
  shouldExit: true,
  logger,
});

• Using Envil with return env value:

import envil from 'envil';

const values = envil(['NODE_ENV', 'PORT'], {
  returnValues: true,
});

I hope this helps!