Library dotenv-webpack doesn't work with vue 3 and webpack-cli

I'm using Vue 3 and Webpack 5 and wanted to install dotenv-webpack, but I can't get it to work.

Here's full code: https://github.com/golebiewska-n/webpack5-vue3

Setup: package.json script I'm using to launch the app

webpack-cli serve

webpack.config.js:

const Dotenv = require('dotenv-webpack')
...
module.exports = (env) => {
  return {
    ...
    plugins: [
       ...
       new Dotenv()
    ]
  }
}

.env (added in the root folder of my app)

VUE_APP_VAR=123

main.js:

console.log(process.env)

and output in console is:

MISSING_ENV_VAR

I tried removing new webpack.DefinePlugin({...}) from plugins in webpack config, but it didn't help.

In fact you successfully loaded the .env file with dotenv-webpack and the VUE_APP_VAR is accessible. It is just you cannot use the entire process.env object as dotenv-webpack does not allow it showing you MISSING_ENV_VAR instead.

If you chnange line 12 in your src\Layout.vue as follows:

- return process.env
+ return process.env.VUE_APP_VAR

you get your 123 value of the variable in your Vue app.

The reason is at the time of building your application with webpack dotenv-webpack replaces the explicit string process.env.SOME_EXPLICIT_VARIABLE_NAME_HERE existing in your code with the actual value of SOME_EXPLICIT_VARIABLE_NAME_HERE if that exist in the Webpack JS environment's actual process.env object.

This means you never get the entire process.env object accessible in your webpack bundle, and the bundle does not comprise the variable names like VUE_APP_VAR=123. This is the goal of dotenv-webpack.

You can get some more details in my answer here.

PS: DefinePlugin, being returned in the build config, could override process.env. It does so in Vue CLI (which is hardly justifiable). So its effect there sould be neutralized manually for dotenv-webpack to work within Vue CLI (v4 and v5) applications as expected.