When NODE_ENV=production and the loadAllDefaults option is enabled, the final configuration becomes:
Modern frameworks—like Next.js, Vite, and Symfony—look for environment files in a specific order. Each file has a unique purpose based on two factors: the target environment (development, production, testing) and whether the file is shared publicly.
This ensures that process.env.PORT is treated as a number, not a string, preventing type-related bugs in your application.
The .env.default file serves as the for all configuration options available in your application. Here's why this approach is superior to traditional methods: .env.default.local
// Overrides for production environment $production: // Production-specific overrides
In production or CI, you don't use files. You use native environment variables set by your hosting provider (AWS Lambda, Heroku, K8s secrets) or your CI runner. These override everything else.
When you add a new dependency that requires a new variable (e.g., STRIPE_WEBHOOK_SECRET ), you must add it to .env.default with a sensible default. Otherwise, the hierarchy breaks. These override everything else
Specific variables intended strictly for the development build pipeline.
Note: The specific order depends on your configuration loader implementation.
Without .env.default.local , both would need to edit the .env file and constantly fight git conflicts. With the pattern, Developer B simply creates a .env.default.local containing REDIS_HOST=host.docker.internal . No conflicts. No friction. 3. Streamlining Monorepo Microservices
Before we champion the solution, we must diagnose the problem. The standard .env pattern has three critical flaws:
If .env.default.local contains real secrets or values, but is not in .gitignore , it could be committed. Usually only .env.example should be versioned.
# .env.default DATABASE_URL=postgres://localhost/app
A shared "base" configuration for local development that everyone could use without leaking secrets. .env.local:
Some advanced frameworks ship with a .env.default file committed to Git by the core maintainers to ensure the app boots out of the box. If you need to change those baseline defaults for your entire local machine across all tasks—but don't want to map them out individually inside mode-specific files—you mirror it with a local counterpart: .env.default.local . 3. Streamlining Monorepo Microservices