Environment Configuration

Environment Configuration Overview

At its core, environment configuration is about doing one thing well inside your single-spa project. Once you understand the pattern, you can apply it consistently across features and teams.

Good environment configuration pays off across the whole codebase: fewer surprises, easier testing, and smoother onboarding. The snippet below is a solid starting point.

# each micro frontend publishes its own bundle + import-map entry
@org/checkout -> https://cdn.example.com/checkout/v3/checkout.js

# update only this app's import-map entry to release it
{ "@org/checkout": "https://cdn.example.com/checkout/v3/checkout.js" }

Deploying a micro frontend is often just updating its import-map URL.

Environment Configuration Example

registerApplication({
  name: '@org/app',
  app: () => System.import('@org/app'),
  activeWhen: ['/app'],
});
start();

• Start from a minimal Environment Configuration example and grow it only as needed.
• Keep configuration explicit so Environment Configuration behaves the same in every environment.
• Name things clearly so teammates understand your Environment Configuration at a glance.
• Add tests around Environment Configuration early to lock in expected behaviour.

Single-SPA Cheatsheet

Core single-spa APIs related to environment configuration.

How Environment Configuration Works in Single-SPA

Environment Configuration is part of how single-spa lets multiple applications — even in different frameworks — coexist on one page. A root config registers each app and controls when it is active.

Deploying a micro frontend is often just updating its import-map URL.

• A root config registers apps and calls start().
• Each app exports bootstrap, mount, and unmount lifecycles.
• activeWhen decides which routes each app owns.
• Import maps resolve each app's bundle at runtime.

Practical Guidance for Environment Configuration

For reliable micro frontends, environment configuration should isolate failures and keep shared state minimal. Let each team own its app end to end while agreeing on a few shared contracts.

Common Mistakes

• Skipping error handling and edge cases when wiring up environment configuration.
• Leaving environment configuration untested, so regressions slip into production.
• Over-engineering environment configuration before you actually need the extra flexibility.
• Ignoring documentation, which makes environment configuration hard for the next developer to change.

Key Takeaways

• Environment Configuration is a core part of working effectively with single-spa.
• Start small and keep environment configuration focused on a single responsibility.
• Apply consistent patterns so environment configuration scales across your project.
• Test and document environment configuration to keep it maintainable over time.