@aapzu/tsdotenv

tsdotenv

Tsdotenv is a package which generates a validated and strongly typed config object from .env file (or process.env variables).

Installation

# using npm
npm install @aapzu/tsdotenv

# using yarn
yarn add @aapzu/tsdotenv

Usage

Create a .env file in the root directory of your project. Add environment-specific variables on new lines in the form of NAME=VALUE. For example:

DB_HOST=localhost
DB_PORT=5432
DEBUG=true

Create a config file as a single place of truth for the environment variables

import { parse } from '@aapzu/tsdotenv'

const SCHEMA = {
  DB_HOST: String,
  DB_PORT: { type: Number, default: 3000 },
  DEBUG: { type: Boolean, optional: true },
  CUSTOM_ENV: { type: ['test', 'prod'] },
  // enums and optionals only get typed properly if the
  // schema is a readonly object
} as const

const config = parse(SCHEMA, {
  path: 'path_to_dotenv_file',
})

/*
  typeof config = {
    DB_HOST: string,
    DB_PORT: number,
    DEBUG: boolean | undefined
    CUSTOM_ENV: 'test' | 'prod'
  }
 */
export default config

Use that config file in other files

import config from '../path/to/config'

console.log(DB_HOST, typeof DB_HOST)
// localhost string

console.log(DB_PORT, typeof DB_PORT)
// 5432 number

console.log(DEBUG, typeof DEBUG)
// true boolean

Schema

Schema is the heart of the library. The parsing and validation of the values is done according to the schema. Possible schema value types are:

name	syntax
string	String
number	Number
boolean	Boolean
enum	['value1', 'value2']
string array	Array(String)
number array	Array(Number)
boolean array	Array(Boolean)

A schema item has type and possibly a default value. If the item has optional: true without a default value, it's possible that the value ends up being undefined.

An example schema is as follows:

const schema = {
  BOOLEAN_ARRAY: Array(Boolean),
  BOOLEAN: {
    type: Boolean,
    optional: true,
  },
  ENUM: {
    type: ['foo', 'bar'],
    default: 'foo',
  },
  NUMBER_ARRAY: Array(Number),
  NUMBER: {
    type: Number,
    default: 42,
  },
  STRING: String,
  STRING_ARRAY: Array(String),
}

Options

path

Default: path.resolve(process.cwd(), '.env')

You may specify a custom path if your file containing environment variables is located elsewhere.

parse(schema, { path: '/custom/path/to/.env' })

camelCaseKeys

Default: false

Maps the keys of the config object into camelCase. Example:

import { parse } from '@aapzu/tsdotenv'

const config = parse({
  DB_HOST: String,
  DB_PORT: { type: Number, default: 3000 },
}, {
  path: 'path_to_dotenv_file',
  camelCaseKeys: true
})

/*
  typeof config = {
    dbHost: string,
    dbPort: number,
  }
 */
export default config

encoding

Default: utf8

You may specify the encoding of your file containing environment variables.

parse(schema, { encoding: 'latin1' })

debug

Default: false

You may turn on logging to help debug why certain keys or values are not being set as you expect.

parse(schema, { debug: process.env.DEBUG })