Jenkins

Understanding jenkins helps you work with single-spa confidently. Here you will learn the core ideas behind jenkins, see working code, and pick up best practices used on real teams.

Jenkins Overview

Jenkins is a building block you will reach for often in single-spa. It keeps related logic together and makes your intent obvious to reviewers and future maintainers.

When you learn jenkins properly, you avoid the guesswork that leads to bugs and rework. The example below shows the shape you will use in most real single-spa projects.

import { registerApplication, start } from 'single-spa';

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

start();

single-spa orchestrates multiple framework apps on one page through a root config.

Jenkins Example

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

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

Single-SPA Cheatsheet

Core single-spa APIs related to jenkins.

API	Example	Purpose
registerApplication	`registerApplication({ name, app, activeWhen })`	Register a micro frontend
activeWhen	`activeWhen: ['/checkout']`	Route ownership
start	`start()`	Begin routing
bootstrap	`export async function bootstrap()`	One-time setup
mount	`export async function mount(props)`	Render the app
unmount	`export async function unmount(props)`	Clean up the app
import map	`systemjs-importmap`	Locate app bundles

How Jenkins Works in Single-SPA

Jenkins 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.

single-spa orchestrates multiple framework apps on one page through a root config.

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 Jenkins

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

Concern	Recommendation
Isolation	One app's crash should not break others
Shared state	Prefer shared utility modules over globals
Routing	Keep activeWhen rules explicit and non-overlapping
Deployment	Release via import-map updates per app

Common Mistakes

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

Key Takeaways

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

Pro Tip

Pair jenkins with automated tests from day one. It is far cheaper to catch single-spa regressions in CI than in production.