vue-cli/docs/guide/mode-and-env.md

Environment Variables and Modes

You can specify env variables by placing the following files in your project root:

.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

An env file simply contains key=value pairs of environment variables:

FOO=bar
VUE_APP_SECRET=secret

Loaded variables will become available to all vue-cli-service commands, plugins and dependencies.

::: tip 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 Vue CLI is bootstrapped have the highest priority and will not be overwritten by .env files. If you have a default NODE_ENV in your environment, you might want to consider removing it. :::

Modes

Mode is an important concept in Vue CLI projects. By default, there are three modes in a Vue CLI project:

• development is used by vue-cli-service serve
• production is used by vue-cli-service build and vue-cli-service test:e2e
• test is used by vue-cli-service test:unit

Note that a mode is different from NODE_ENV, as a mode can contain multiple environment variables. That said, each mode does set NODE_ENV to the same value by default - for example, NODE_ENV will be set to "development" in development mode.

You can set environment variables only available to a certain mode by postfixing the .env file. For example, if you create a file named .env.development in your project root, then the variables declared in that file will only be loaded in development mode.

You can overwrite the default mode used for a command by passing the --mode option flag. For example, if you want to use development variables in the build command, add this to your package.json scripts:

"dev-build": "vue-cli-service build --mode development",

Example: Staging Mode

Assuming we have an app with the following .env file:

VUE_APP_TITLE=My App

And the following .env.staging file:

NODE_ENV=production
VUE_APP_TITLE=My App (staging)

• vue-cli-service build builds a production app, loading .env, .env.production and .env.production.local if they are present;

• vue-cli-service build --mode staging builds a production app in staging mode, using .env, .env.staging and .env.staging.local if they are present.

In both cases, the app is built as a production app because of the NODE_ENV, but in the staging version, process.env.VUE_APP_TITLE is overwritten with a different value.

Using Env Variables in Client-side Code

Only variables that start with VUE_APP_ will be statically embedded into the client bundle with webpack.DefinePlugin. You can access them in your application code:

console.log(process.env.VUE_APP_SECRET)

During build, process.env.VUE_APP_SECRET will be replaced by the corresponding value. In the case of VUE_APP_SECRET=secret, it will be replaced by "secret".

In addition to VUE_APP_* variables, there are also two special variables that will always be available in your app code:

• NODE_ENV - this will be one of "development", "production" or "test" depending on the mode the app is running in.
• BASE_URL - this corresponds to the baseUrl option in vue.config.js and is the base path your app is deployed at.

All resolved env variables will be available inside public/index.html as discussed in HTML - Interpolation.

::: tip You can have computed env vars in your vue.config.js file. They still need to be prefixed with VUE_APP_. This is useful for version info process.env.VUE_APP_VERSION = require('./package.json').version :::

Local Only Variables

Sometimes you might have env variables that should not be committed into the codebase, especially if your project is hosted in a public repository. In that case you should use an .env.local file instead. Local env files are ignored in .gitignore by default.

.local can also be appended to mode-specific env files, for example .env.development.local will be loaded during development, and is ignored by git.