Environment variables for vue webpack frontends

dev.env.js

// src/config/dev.env.js
export default {
  GOOGLE_MAPS_API_KEY: 'THE KEY'
}

index.js

// src/config/index.js
import _ from 'lodash'
import EnvConfig from 'env-config'
export default _.merge(EnvConfig, {
  VERIFICATION_DURATION: 3600
})

prod.env.js

// src/config/prod.env.js
export default {
  GOOGLE_MAPS_API_KEY: 'THE PRODUCTION KEY'
}

webpack.dev.conf.js

// build/dev.env.js
module.exports = merge(baseWebpackConfig, {
  resolve: {
    alias: {
      'env-config': path.resolve(__dirname, '../src/config/dev.config.js')
    }
  }
})

webpack.prod.conf.js

// build/prod.env.js
var webpackConfig = merge(baseWebpackConfig, {
  resolve: {
    alias: {
      'env-config': path.resolve(__dirname, '../src/config/prod.config.js')
    }
  }
}

This is my solution for environment variables that are available in a Vue webpack environment.
I've stripped anything else out so you can read the code better.