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Env Variables and Modes

Env Variables

Vite exposes env variables on the special import.meta.env object. Some built-in variables are available in all cases:

  • import.meta.env.MODE: {string} the mode the app is running in.

  • import.meta.env.BASE_URL: {string} the base url the app is being served from. This is determined by the base config option.

  • import.meta.env.PROD: {boolean} whether the app is running in production.

  • import.meta.env.DEV: {boolean} whether the app is running in development (always the opposite of import.meta.env.PROD)

  • import.meta.env.SSR: {boolean} whether the app is running in the server.

Production Replacement

During production, these env variables are statically replaced. It is therefore necessary to always reference them using the full static string. For example, dynamic key access like import.meta.env[key] will not work.

It will also replace these strings appearing in JavaScript strings and Vue templates. This should be a rare case, but it can be unintended. You may see errors like Missing Semicolon or Unexpected token in this case, for example when "process.env.NODE_ENV" is transformed to ""development": ". There are ways to work around this behavior:

  • For JavaScript strings, you can break the string up with a Unicode zero-width space, e.g. 'import.meta\u200b.env.MODE'.

  • For Vue templates or other HTML that gets compiled into JavaScript strings, you can use the <wbr> tag, e.g. import.meta.<wbr>env.MODE.

.env Files

Vite uses dotenv to load additional environment variables from the following files in your environment directory:

.env                # loaded in all cases
.env.local          # loaded in all cases, ignored by git
.env.[mode]         # only loaded in specified mode
.env.[mode].local   # only loaded in specified mode, ignored by git

Env Loading Priorities

An env file for a specific mode (e.g. .env.production) will take higher priority than a generic one (e.g. .env).

In addition, environment variables that already exist when Vite is executed have the highest priority and will not be overwritten by .env files. For example, when running VITE_SOME_KEY=123 vite build.

.env files are loaded at the start of Vite. Restart the server after making changes.

Loaded env variables are also exposed to your client source code via import.meta.env as strings.

To prevent accidentally leaking env variables to the client, only variables prefixed with VITE_ are exposed to your Vite-processed code. e.g. for the following env variables:

VITE_SOME_KEY=123
DB_PASSWORD=foobar

Only VITE_SOME_KEY will be exposed as import.meta.env.VITE_SOME_KEY to your client source code, but DB_PASSWORD will not.

js
console.log(import.meta.env.VITE_SOME_KEY) // 123
console.log(import.meta.env.DB_PASSWORD) // undefined

Also, Vite uses dotenv-expand to expand variables out of the box. To learn more about the syntax, check out their docs.

Note that if you want to use $ inside your environment value, you have to escape it with \.

KEY=123
NEW_KEY1=test$foo   # test
NEW_KEY2=test\$foo  # test$foo
NEW_KEY3=test$KEY   # test123

If you want to customize the env variables prefix, see the envPrefix option.

SECURITY NOTES

  • .env.*.local files are local-only and can contain sensitive variables. You should add *.local to your .gitignore to avoid them being checked into git.

  • Since any variables exposed to your Vite source code will end up in your client bundle, VITE_* variables should not contain any sensitive information.

IntelliSense for TypeScript

By default, Vite provides type definitions for import.meta.env in vite/client.d.ts. While you can define more custom env variables in .env.[mode] files, you may want to get TypeScript IntelliSense for user-defined env variables that are prefixed with VITE_.

To achieve this, you can create an env.d.ts in src directory, then augment ImportMetaEnv like this:

typescript
/// <reference types="vite/client" />

interface ImportMetaEnv {
  readonly VITE_APP_TITLE: string
  // more env variables...
}

interface ImportMeta {
  readonly env: ImportMetaEnv
}

If your code relies on types from browser environments such as DOM and WebWorker, you can update the lib field in tsconfig.json.

json
{
  "lib": ["WebWorker"]
}

Modes

By default, the dev server (dev command) runs in development mode and the build command runs in production mode.

This means when running vite build, it will load the env variables from .env.production if there is one:

# .env.production
VITE_APP_TITLE=My App

In your app, you can render the title using import.meta.env.VITE_APP_TITLE.

In some cases, you may want to run vite build with a different mode to render a different title. You can overwrite the default mode used for a command by passing the --mode option flag. For example, if you want to build your app for a staging mode:

bash
vite build --mode staging

And create a .env.staging file:

# .env.staging
VITE_APP_TITLE=My App (staging)

As vite build runs a production build by default, you can also change this and run a development build by using a different mode and .env file configuration:

# .env.testing
NODE_ENV=development

Released under the MIT License. (d953536a)