Zero-downtime deployment concept in Express - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is zero-downtime deployment?

Zero-downtime deployment is a method of updating an application without stopping the service or causing any interruption to users.

beginner

Why is zero-downtime deployment important for web applications?

It ensures users can keep using the app without interruptions, improving user experience and avoiding lost traffic or revenue.

intermediate

Name one common technique used in zero-downtime deployment with Express apps.

Using a process manager like PM2 to reload the app gracefully without dropping connections.

intermediate

How does a load balancer help achieve zero-downtime deployment?

It directs traffic to healthy instances and can route users away from servers being updated, allowing updates without service interruption.

intermediate

What is a graceful shutdown in the context of zero-downtime deployment?

It means the server stops accepting new requests but finishes handling ongoing requests before shutting down, preventing dropped connections.

What does zero-downtime deployment prevent?

A Faster server startup

B More memory usage

C Service interruptions during updates

D Longer downtime

Zero-downtime deployment prevents service interruptions during updates, keeping the app available.

Which tool can help reload an Express app without dropping connections?

A PM2

B Git

C Webpack

D Nodemon

PM2 can reload apps gracefully, enabling zero-downtime deployment.

What role does a load balancer play in zero-downtime deployment?

A Caches static files

B Routes traffic to healthy servers

C Manages database connections

D Compiles code

Load balancers route traffic to healthy servers, helping avoid downtime during updates.

What is a graceful shutdown?

A Ignoring ongoing requests

B Immediately killing the server process

C Restarting the server every minute

D Stopping new requests but finishing current ones before shutdown

Graceful shutdown stops new requests but completes ongoing ones to avoid dropped connections.

Which of these is NOT a benefit of zero-downtime deployment?

A Longer maintenance windows

B No service interruptions

C Improved user experience

D Continuous availability

Zero-downtime deployment aims to reduce maintenance windows, not make them longer.

Explain how zero-downtime deployment works in an Express app environment.

Think about how the app keeps running while updating.

Describe why zero-downtime deployment is important for user experience and business.

Consider what happens if the app goes offline during updates.