@ashgw/ts-env NPM

@ashgw/ts-env

A lightweight TypeScript utility for managing and validating environment variables with zod.

What It Does

Schema Validation: Validate environment variables with a zod schema.
Prefix Handling: Support prefixes like NEXT_PUBLIC_ for variables.
Flexible Prefix Control: Exclude prefixes for specific variables as needed.
Type Safety: Access environment variables with full type safety.
Optional Validation: Skip validation when required.
Custom Runtime Environment: Explicitly define environment variables for client-side code in monorepos.

Why Not Use Other Options?

t3-oss/t3-env: Very convoluted. Also doesn't have a prefix. So I added a prefix option e.g: prefix: 'NEXT_PUBLIC', you add it once and that's it.
envalid: it doesn't use zod, which means additional overhead for importing and learning a new schema validation lib. You already know zod, so might as well use it.
envsafe: too many options, can lead to mental overhead, and I don't like mental overhead, you probably don't too, plus, last commit was like 2 years ago.
your own library: If you've already created one, it probably sucks; this one doesn't.

Installation

npm install @ashgw/ts-env zod

or with pnpm:

pnpm add @ashgw/ts-env zod

Usage

Basic Example

import { z } from 'zod';
import { createEnv } from '@ashgw/ts-env';

const env = createEnv({
  vars: {
    API_URL: z.string().url(),
    PORT: z.string().regex(/^\d+$/, 'PORT must be a number'),
  },
});

console.log(env.API_URL); // e.g., "https://example.com"
console.log(env.PORT);    // e.g., "3000"

With Prefixes

If your environment variables have a common prefix, you can specify it:

import { z } from 'zod';
import { createEnv } from '@ashgw/ts-env';

const env = createEnv({
  vars: {
    API_URL: z.string().url(),
    PORT: z.string().regex(/^\d+$/, 'PORT must be a number'),
  },
  prefix: 'NEXT_PUBLIC',
});

console.log(env.NEXT_PUBLIC_API_URL); // e.g., "https://example.com"
console.log(env.NEXT_PUBLIC_PORT);    // e.g., "3000"

Disabling Prefix for Specific Variables

Disable the prefix for specific variables using the disablePrefix option:

import { z } from 'zod';
import { createEnv } from '@ashgw/ts-env';

const env = createEnv({
  vars: {
    API_URL: z.string().url(),
    NODE_ENV: z.string().min(1),
    PORT: z.string().regex(/^\d+$/, 'PORT must be a number'),
  },
  prefix: 'NEXT_PUBLIC',
  disablePrefix: ['NODE_ENV'],
});

console.log(env.NEXT_PUBLIC_API_URL); // e.g., "https://example.com"
console.log(env.NEXT_PUBLIC_PORT);    // e.g., "3000"
console.log(env.NODE_ENV);            // e.g., "development"

Skipping Validation

To skip validation, set skipValidation to true:

import { z } from 'zod';
import { createEnv } from '@ashgw/ts-env';

const env = createEnv({
  vars: {
    API_URL: z.string(),
    PORT: z.string(),
  },
  skipValidation: true,
});

console.log(env.API_URL);
console.log(env.PORT);

Custom Runtime Environment

For cases where you need to explicitly define environment variables (especially in client-side code), use the runtimeEnv option:

import { z } from 'zod';
import { createEnv } from '@ashgw/ts-env';

const isBrowser = typeof window !== 'undefined';

const env = createEnv({
  vars: {
    API_URL: z.string().url(),
    API_KEY: z.string().min(1),
  },
  prefix: 'NEXT_PUBLIC',
  runtimeEnv: {
    NEXT_PUBLIC_API_URL: process.env.NEXT_PUBLIC_API_URL,
    NEXT_PUBLIC_API_KEY: process.env.NEXT_PUBLIC_API_KEY,
  },
  skipValidation: isBrowser,
});

API

`createEnv`

Parameters

vars: A record of variable names and their zod schemas.
prefix (optional): A prefix to apply to variables (e.g., 'NEXT_PUBLIC').
disablePrefix (optional): An array of variable names to exclude from the prefix.
skipValidation (optional): If true, skips validation.
runtimeEnv (optional): Explicitly define environment variables, useful for client-side code.

Returns

A type-safe object containing your environment variables.

Error Handling

When validation fails, createEnv throws an error with details:

❌ Invalid environment variables: {
  NEXT_PUBLIC_WWW_URL: [ 'Invalid url' ],
  NEXT_PUBLIC_WWW_GOOGLE_ANALYTICS_ID: [
    'String must contain at least 7 character(s)',
    'Invalid input: must start with "G-"'
  ],
  NEXT_PUBLIC_BLOG_GOOGLE_ANALYTICS_ID: [
    'String must contain at least 7 character(s)',
    'Invalid input: must start with "G-"'
  ],
  NEXT_PUBLIC_BLOG_URL: [ 'Invalid url' ]
}

Here's an example in action.

Presets

To simplify the management of environment variables for specific platforms, you can use presets provided by the library. For example, if you're deploying on Vercel, you can easily include all the relevant environment variables by importing and using the dedicated Vercel preset.

Example with Vercel Preset

Supported presets

Vercel
Netlify
Fly
Railway

NextJS Monorepos

When working with NextJS in a monorepo setup, you may encounter issues with environment variables, especially in client components. This is because:

In a monorepo, your environment configuration might be in a shared package (e.g., @packages/env)
NextJS has special handling for environment variables, particularly those with the NEXT_PUBLIC_ prefix
Client components can't access server-side environment variables directly

In a standard NextJS app, environment variables work seamlessly between server and client components when defined in .env files at the app root. So the configs you see above will work just fine. However, in monorepos:

Environment variables defined in shared packages may not be properly injected into client components
Even with transpilation of packages, NextJS might not correctly process environment variables from shared packages

So to solve this issue, use the runtimeEnv option to explicitly define your environment variables:

import { z } from 'zod';
import { createEnv } from '@ashgw/ts-env';

const isBrowser = typeof window !== 'undefined';

export const env = createEnv({
  vars: {
    NODE_ENV: z.enum(["production", "development", "preview"]),
    WWW_URL: z.string().url(),
    BLOG_URL: z.string().url(),
    WWW_GOOGLE_ANALYTICS_ID: z.string().min(7).startsWith("G-"),
    BLOG_GOOGLE_ANALYTICS_ID: z.string().min(7).startsWith("G-"),
  },
  disablePrefix: ["NODE_ENV"],
  prefix: "NEXT_PUBLIC",
  // Explicitly define environment variables
  runtimeEnv: {
    NEXT_PUBLIC_WWW_GOOGLE_ANALYTICS_ID:
      process.env.NEXT_PUBLIC_WWW_GOOGLE_ANALYTICS_ID,
    NEXT_PUBLIC_BLOG_GOOGLE_ANALYTICS_ID:
      process.env.NEXT_PUBLIC_BLOG_GOOGLE_ANALYTICS_ID,
    NEXT_PUBLIC_WWW_URL: process.env.NEXT_PUBLIC_WWW_URL,
    NEXT_PUBLIC_BLOG_URL: process.env.NEXT_PUBLIC_BLOG_URL,
    NODE_ENV: process.env.NODE_ENV,
  },
  skipValidation: isBrowser, // Skip validation in the browser since variables are injected at build time
});

runtimeEnv is typesafe too so you won't have to worry about missing any variable

Here's how you might configure it in a monorepo.

Additional Configuration for Turborepo

If you're using Turborepo, remember to add your environment variables to turbo.json:

{
  "pipeline": {
    "build": {
      "env": [
        "NODE_ENV",
        "NEXT_PUBLIC_WWW_URL",
        "NEXT_PUBLIC_BLOG_URL",
        "NEXT_PUBLIC_WWW_GOOGLE_ANALYTICS_ID",
        "NEXT_PUBLIC_BLOG_GOOGLE_ANALYTICS_ID"
      ]
    }
  }
}

This ensures Turborepo correctly passes these environment variables to your build processes.