envsafe

envsafe 🔒

Validate access to environment variables and parse them to the right type.

========================================
❌ Invalid environment variables:
    API_URL: Invalid url input: "http//example.com/graphql"
💨 Missing environment variables:
    MY_VAR: Missing value
    PORT: Missing value
========================================

Mostly based on the great project envalid, but with some key differences:

• Written in 100% TypeScript
• Always strict - only access the variables you have defined
• Built for node.js and the browser
• No dependencies - tiny bundle for browser/isomorphic apps

• How to use
  • Install
  • Basic usage
• Built-in validators
  • Possible options
• Custom validators/parsers
• Error reporting

How to use

Works the same in the browser and in node. See the ./examples-folder for more examples.

Install

yarn add envsafe

npm i envsafe --save

Basic usage

import { str, envsafe, port, url } from 'envsafe';

export const env = envsafe({
  NODE_ENV: str({
    devDefault: 'development',
    choices: ['development', 'test', 'production'],
  }),
  PORT: port({
    devDefault: 3000,
  }),
  API_URL: url({
    devDefault: 'https://example.com/graphql',
  }),
  AUTH0_CLIENT_ID: str({
    devDefault: 'xxxxx',
  }),
  AUTH0_DOMAIN: str({
    devDefault: 'xxxxx.auth0.com',
  }),
});

It defaults to using process.env as a base for plucking the vars, but it can be overridden like this:

export const env = envsafe(
  {
    ENV_VAR: str({
      devDefault: 'myvar',
    }),
  },
  {
    env: window.__ENVIRONMENT__,
  },
);

Built-in validators

Function	return value	Description
str()	string	Passes string values through, will ensure an value is present unless a default value is given.
bool()	boolean	Parses env var strings "0", "1", "true", "false", "t", "f" into booleans
num()	number	Parses an env var (eg. "42", "0.23", "1e5") into a Number
port()	number	Ensures an env var is a TCP port (1-65535)
url()	string	Ensures an env var is a url with a protocol and hostname
email()	string	Ensures an env var is an email address
json()	unknown	Parses an env var with JSON.parse

Possible options

All optional.

Name	Type	Description
choices	TValue[]	Allow-list for values
default	TValue / string	A fallback value, which will be used if the env var wasn't specified. Providing a default effectively makes the env var optional.
devDefault	TValue / string	A fallback value to use only when NODE_ENV is not production. This is handy for env vars that are required for production environments, but optional for development and testing.

These values below are not used by the library and only for description of the variables.

Name	Type	Description
desc	string	A string that describes the env var.
example	string / TValue	An example value for the env var.
docs	string	A url that leads to more detailed documentation about the env var.

Custom validators/parsers

import { makeValidator, envsafe } from 'envsafe';

const barParser = makeValidator<'bar'>(input => {
  if (input !== 'bar') {
    throw new InvalidEnvError(`Expected '${input}' to be 'bar'`);
  }
  return 'bar';
});

const env = envsafe({
  FOO: barParser(),
});

Error reporting

By default the reporter will

• Make a readable summary of your issues
• console.error-log an error
• Call process.exit(1) / window.alert(text)
• Throw an error

Can be overridden by the reporter-property

const env = envsafe(
  {
    MY_VAR: str(),
  },
  {
    reporter({ errors, output, env }) {
      // do stuff
    },
  },
);

Strict mode (recommended for JS-users)

By default envsafe returns a Readonly<T> which in TypeScript ensures the env can't be modified and undefined properties from being accessed, but if you're using JavaScript you are still able to access env vars that don't exist. Therefore there's a strict mode option, which is recommended if your project is using vanilla JS, but not recommended if you use TypeScript.

It wraps the function in Object.freeze and a Proxy that disallows access to any props that aren't defined.

import { envsafe, str } from 'envsafe';

export const browserEnv = envsafe(
  {
    MY_ENV: str(),
  },
  {
    strict: true,
  },
);