env-to-t3

This is a CLI to generate a TypeScript code to use environment variables safely using T3 env.

Why?

Accessing environment variables directly (e.g., process.env.API_KEY) in your TypeScript code is not safe. If you forget to add the environment variable, your code might break. That's why a tool like T3 Env can be very helpful. You can use your environment variables in a safe way and fully typed thanks to Zod.

But writing the code is a bit tedious. For example, you have 3 environment variables that you want to use in your code. During the development, you need to write the .env file like this:

DATABASE_URL=postgres://localhost:5432/my-app
OPEN_AI_API_KEY=1234567890
NEXT_PUBLIC_PUBLISHABLE_KEY=1234567890

Then write the code like this:

import { createEnv } from '@t3-oss/env-nextjs'
import { z } from 'zod'

export const env = createEnv({
  server: {
    DATABASE_URL: z.string().url(),
    OPEN_AI_API_KEY: z.string().min(1),
  },
  client: {
    NEXT_PUBLIC_PUBLISHABLE_KEY: z.string().min(1),
  },
  experimental__runtimeEnv: {
    NEXT_PUBLIC_PUBLISHABLE_KEY: process.env.NEXT_PUBLIC_PUBLISHABLE_KEY,
  },
})

Notice that you need to write NEXT_PUBLIC_PUBLISHABLE_KEY four times in total.

By using this script, you don't need to write the code by hands anymore. Just run the script and it will generate the code for you.

Features

• By default, all environment variables will be considered as string.
• When the environment variable ends with _URL, it will be converted to a z.string().url() type.
• When the environment variable has NEXT_PUBLIC_ prefix, it will be considered as a client-side environment variable.
• When the environment variable has # required comment, it will be has a .min(1) constraint.
• When the environment variable has # number comment, it will be has a .number() constraint.

Example, you have the following .env file:

DATABASE_URL=abcd
OPEN_AI_API_KEY=1 # number required
NEXT_PUBLIC_PUBLISHABLE_KEY=abcd
MINIMUM_DAYS=1 # number

Running env-to-t3 script will generate the following env.ts file:

import { createEnv } from '@t3-oss/env-nextjs'
import { z } from 'zod'

export const env = createEnv({
  server: {
    DATABASE_URL: z.string(),
    OPEN_AI_API_KEY: z.number().min(1),
    MINIMUM_DAYS: z.number(),
  },
  client: {
    NEXT_PUBLIC_PUBLISHABLE_KEY: z.string(),
  },
  experimental__runtimeEnv: {
    NEXT_PUBLIC_PUBLISHABLE_KEY: process.env.NEXT_PUBLIC_PUBLISHABLE_KEY,
  },
})

Install

npm i -g env-to-t3

Or you can also directly execute the command:

npx env-to-t3 -i .env

CLI

  Usage
    $ env-to-t3 [input]

  Options
    --input, -i <type> The path to the environment file.  [Default: .env]
    --output, -o The path to write the output. [Default: env.ts]
    --client-prefix, -cp The prefix for client-side environment variables. [Default: NEXT_PUBLIC_]

  Examples
    $ env-to-t3 --input .env

Notes

• The generated code is compatible with Next.js >= 13.4.4 as mentioned in the T3 env documentation.

Development

Run

npx tsx source/cli.tsx --url "https://example.com"

License

MIT

Contact

Nico Prananta