Not setting up proper fallbacks for missing environment variables

If you’re not setting up proper fallbacks for missing environment variables, it can lead to unexpected errors, especially in production environments. Here’s how to handle it effectively:

1. Importance of Fallbacks

• Prevents Crashes: Missing variables can cause the app to crash or behave unpredictably.
• Graceful Degradation: Provides default behavior instead of failing completely.
• Security: Avoids exposing sensitive errors in production.

2. Setting Up Fallbacks in Node.js

Using process.env with Defaults:

const port = process.env.PORT || 3000;
const dbHost = process.env.DB_HOST || 'localhost';
const apiKey = process.env.API_KEY || 'default-api-key';

Using dotenv with Fallbacks:

If using .env files:

# .env
PORT=5000
DB_HOST=database.example.com

In code:

require('dotenv').config();
const port = process.env.PORT || 3000;

3. Using Validation Libraries

Consider using libraries like joi or env-schema to validate environment variables:

const Joi = require('joi');

const envSchema = Joi.object({
  NODE_ENV: Joi.string().valid('development', 'production').default('development'),
  PORT: Joi.number().default(3000),
  DB_HOST: Joi.string().required(),
}).unknown(true);

const { error, value: envVars } = envSchema.validate(process.env);
if (error) {
  throw new Error(`Environment validation error: ${error.message}`);
}

4. Handling Missing Variables Gracefully

• Logging Warnings: Instead of crashing, log a warning: if (!process.env.DB_HOST) { console.warn('DB_HOST is not set, using default localhost.'); }
• Graceful Shutdown: In critical cases, shut down the app gracefully: if (!process.env.API_KEY) { console.error('Critical error: API_KEY is missing.'); process.exit(1); }

5. Best Practices

• Document Required Variables: Keep a .env.example file.
• Avoid Hardcoding: Always prefer environment variables over hardcoding sensitive values.
• Test for Missing Variables: Use CI/CD pipelines to check for missing environment variables.

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