Where a ship may berth

The harbour’s machinery seen from the inside. One small box on it says “picks a node for a pod”. This lesson is about that box: the berth master, and the rules it follows when it decides where each ship may tie up.

Before you start. A pod is one running copy of a program, a ship, and a node is one machine in the cluster (the group of machines Kubernetes runs on), a quay where ships tie up (Pods, ReplicaSets & Deployments (the ownership chain)). Inside Kubernetes, one part called the scheduler picks a node for every new pod, and nothing runs until it has picked (Under the Hood (Kubernetes Internals)). When it cannot pick, the pod sits in Pending, the status you learned to read in The cluster that won't sail (Kubernetes troubleshooting). From Processes, Threads & the Kernel you need one word: the kernel, the part of the machine that decides which program runs next.