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Vue.js Environment Variables

When building a Vue.js application for deployment, you'll often need different configurations based on the environment where your application is running. Environment variables provide a way to manage these configurations securely and effectively.

What Are Environment Variables?​

Environment variables are dynamic values that can affect the way running processes behave on a computer. In web development, they allow you to:

  • Store sensitive information like API keys separately from your code
  • Configure different settings for development, testing, and production environments
  • Change application behavior without modifying the codebase

Why Use Environment Variables in Vue.js?​

Using environment variables in your Vue.js projects offers several advantages:

  1. Security: Keep sensitive information like API keys out of your source code
  2. Environment-specific configuration: Maintain different settings for development, staging, and production
  3. Simplified deployment: Deploy the same code to different environments with environment-specific configurations
  4. Better team collaboration: Team members can have their own local configurations

Environment Variables in Vue CLI Projects​

Vue CLI provides built-in support for environment variables through .env files.

Basic Setup​

  1. Create environment files in your project root:
├── .env                # loaded in all environments
├── .env.local          # loaded in all environments, ignored by git
├── .env.development    # only loaded in development environment
├── .env.production     # only loaded in production environment
  1. Add variables to these files using the format:
VUE_APP_API_URL=https://api.example.com
VUE_APP_DEBUG=true
Important

In Vue CLI projects, only variables that begin with VUE_APP_ will be embedded in your application bundle!

Accessing Environment Variables​

You can access these variables in your Vue components:

javascript
// Using in a component
export default {
  mounted() {
    console.log(process.env.VUE_APP_API_URL);
    console.log(process.env.VUE_APP_DEBUG);
  }
}

Or in your Vue templates:

html
<template>
  <div>
    <p>API URL: {{ process.env.VUE_APP_API_URL }}</p>
    <p v-if="process.env.VUE_APP_DEBUG">Debug mode is ON</p>
  </div>
</template>

Environment Variables in Vite Projects​

If you're using Vite (Vue 3's recommended build tool), the process is slightly different.

Basic Setup for Vite​

  1. Create .env files similar to Vue CLI:
├── .env                # loaded in all environments
├── .env.local          # loaded in all environments, ignored by git
├── .env.development    # only loaded in development environment
├── .env.production     # only loaded in production environment
  1. Add variables with the format:
VITE_API_URL=https://api.example.com
VITE_DEBUG=true
Important

In Vite projects, only variables prefixed with VITE_ are exposed to your client-side code!

Accessing Variables in Vite Projects​

Access these variables in your components:

javascript
// Using in a component
export default {
  mounted() {
    console.log(import.meta.env.VITE_API_URL);
    console.log(import.meta.env.VITE_DEBUG);
  }
}

Or in your templates:

html
<template>
  <div>
    <p>API URL: {{ import.meta.env.VITE_API_URL }}</p>
    <p v-if="import.meta.env.VITE_DEBUG">Debug mode is ON</p>
  </div>
</template>

Environment Variable Priority​

The order of precedence for environment files is:

Where [mode] is the current environment (development, production, or test).

Real-World Examples​

Configuring API Endpoints​

A common use case is configuring different API endpoints for development and production:

.env.development

VUE_APP_API_URL=http://localhost:3000/api

.env.production

VUE_APP_API_URL=https://api.myproduct.com/v1

ApiService.js

javascript
import axios from 'axios';

const apiClient = axios.create({
  baseURL: process.env.VUE_APP_API_URL,
  timeout: 10000,
  headers: {
    'Content-Type': 'application/json'
  }
});

export default {
  getUsers() {
    return apiClient.get('/users');
  },
  getUserById(id) {
    return apiClient.get(`/users/${id}`);
  }
  // Other API methods...
};

Feature Flags​

Use environment variables to enable/disable features:

.env.development

VUE_APP_FEATURE_NEW_UI=true
VUE_APP_ENABLE_ANALYTICS=false

.env.production

VUE_APP_FEATURE_NEW_UI=false
VUE_APP_ENABLE_ANALYTICS=true

App.vue

html
<template>
  <div>
    <NewUI v-if="isNewUIEnabled" />
    <LegacyUI v-else />
    
    <analytics-tracker v-if="analyticsEnabled" />
  </div>
</template>

<script>
import NewUI from './components/NewUI.vue';
import LegacyUI from './components/LegacyUI.vue';
import AnalyticsTracker from './components/AnalyticsTracker.vue';

export default {
  components: {
    NewUI,
    LegacyUI,
    AnalyticsTracker
  },
  data() {
    return {
      isNewUIEnabled: process.env.VUE_APP_FEATURE_NEW_UI === 'true',
      analyticsEnabled: process.env.VUE_APP_ENABLE_ANALYTICS === 'true'
    }
  }
}
</script>

Best Practices​

  1. Never commit sensitive information: Add .env.local and .env.*.local to your .gitignore file
  2. Document required variables: Include a .env.example file with dummy values to document required variables
  3. Validate environment variables: Check for required variables when your app starts
  4. Minimize client-exposed variables: Only expose what's necessary to the client
  5. Use typed environment variables: Convert strings to appropriate types when accessing them

Example of validating required variables:

javascript
// src/utils/validateEnv.js
export default function validateEnv() {
  const requiredVars = ['VUE_APP_API_URL'];
  
  const missing = requiredVars.filter(
    varName => !process.env[varName]
  );
  
  if (missing.length > 0) {
    throw new Error(
      `Missing required environment variables: ${missing.join(', ')}`
    );
  }
}

// src/main.js
import validateEnv from './utils/validateEnv';

// Validate environment variables before starting app
validateEnv();

// Initialize Vue app
// ...

Environment Variables in Deployment Platforms​

Different deployment platforms handle environment variables differently:

Netlify​

Set environment variables in the Netlify UI under Site settings > Build & deploy > Environment variables

For local development with Netlify CLI, create a .env file and use the -e flag:

bash
netlify dev -e .env.local

Vercel​

Set environment variables in the Vercel UI under Project Settings > Environment Variables

You can also set variables for different environments (production, preview, development).

Docker​

Pass environment variables when running a container:

bash
docker run -e VUE_APP_API_URL=https://api.example.com my-vue-app

Or use a docker-compose.yml file:

yaml
version: '3'
services:
  app:
    build: .
    environment:
      - VUE_APP_API_URL=https://api.example.com
      - VUE_APP_DEBUG=false

Summary​

Environment variables are essential for configuring Vue.js applications across different environments. They help keep sensitive information out of your source code and enable environment-specific configurations.

Key takeaways:

  • Use .env files to define environment variables
  • Prefix variables with VUE_APP_ for Vue CLI projects or VITE_ for Vite projects
  • Never commit sensitive information to your code repository
  • Use environment variables for API endpoints, feature flags, and other configuration settings
  • Configure environment variables appropriately for your deployment platform

Additional Resources​

Exercises​

  1. Create a Vue application with different API endpoints for development and production.
  2. Implement feature flags that enable/disable certain features based on the environment.
  3. Set up environment-specific logging that only shows debug information in development.
  4. Configure environment variables for a third-party service like Google Maps or Firebase.
  5. Create a configuration validation system that checks for required environment variables at startup.

If you spot any mistakes on this website, please let me know at [email protected]. I’d greatly appreciate your feedback! :)