The problem

Imagine you built a little web shop and packed it into a container: a tidy box holding your code and everything it needs to run, so it runs the same on any computer.

In Kubernetes, every container rides inside a . Here is the one you'll meet all through this book:

Podysseus, hero of the harbor, at your service! It’s a bit of a mouthful, so just call me Pod.

On Monday you run the shop on one computer. Picture it as one small Greek ship with one crew member. 10 people visit. Smooth sailing.

Monday: 10 visitors

Tuesday: 10,000 visitors

On Tuesday the shop gets popular. The computer runs out of steam, the app crashes, and nobody is awake to restart it. Three problems at once:

1. One copy isn't enough to serve everyone.
2. One computer is a single point of failure. If it dies, the shop is gone.
3. Nobody is watching. A crash at 3am stays crashed until morning.

What you want is someone who will run several copies, spread them across several computers, and replace any copy that dies, automatically, forever. The ancient Greeks called that person the kybernētēs, the helmsman. Say it a few times and you get Kubernetes.