clever-env

clever-env validates and sanitizes environment variables and parses them to the right type.

Why validate environment variables?

Environment variables are injected from outside into your application, and you have no control over them within your codebase.

For example, a section of your code relies on the existence of the PORT variable. There is no guarantee that at the time of running your application, the PORT variable exists and has the correct value, so you must validate it.

Installation

npm install clever-env

Usage

import cleverEnv from 'clever-env';

const env = cleverEnv((schema) => ({
  NODE_ENV: schema.enum({
    values: ['production', 'development', 'test'] as const,
    default: 'development'
  }),
  PORT: schema.number({ range: 'tcp' }),
  URL: schema.string({ format: 'url' }),
  GITHUB_USERNAME: schema.string({
    default: 'screfy'
  })
}));

It defaults to using process.env as a base for parsing environment variables, but it can be overridden like this:

import { cleverEnv } from 'clever-env';

const env = cleverEnv((schema) => ({
    ...
  }),
  {
    env: { PORT: 80 }
  }
);

Validators

The library comes with the following built-in validators.

schema.string

Ensures the value is a string and is not undefined or empty.

{
  // Must be a valid email:
  EMAIL: schema.string({ format: 'email' }),
  // Must be a valid URL:
  URL: schema.string({ format: 'url' }),
  // Must be a valid UUID v4:
  UUID: schema.string({ format: 'uuid' }),
  // Must be in the provided format:
  REGEX: schema.string({ format: /[a-z]/ }),
}

schema.number

Enforces the value to be a valid string representation of a number.

{
  // Must be in the TCP range (1-65535):
  TCP: schema.number({ range: 'tcp' }),
  // Must be in the range 1-100:
  RANGE: schema.number({ range: [1, 100] }),
}

schema.boolean

Enforces the value to be a valid string representation of a boolean. The following values are considered as a valid booleans and will be parsed:

• 'true', '1' are parsed to true
• 'false', '0' are parsed to false

{
  BOOL: schema.boolean(),
}

schema.enum

Forces the value to be one of the pre-defined values.

{
  NODE_ENV: schema.enum({
    values: ['production', 'development', 'test'] as const,
    default: 'development'
  }),
}

NOTE: We use as const to allow TypeScript to properly type our enum values.