Inside Kubernetes
The control plane and the nodes: API server, etcd, scheduler, controllers and kubelet, and how a pod gets created.
Transcript
A Kubernetes cluster has a control plane that makes decisions, and worker nodes that run your containers.
Every request goes through the API server. It is the front door, and the only component that talks to the database.
The desired state is stored in etcd, a consistent key-value store.
The scheduler watches for pods with no node, and picks a node for each one.
Controllers compare the desired state with reality, and act to close the gap.
On each node, the kubelet sees the pods assigned to it, and asks the container runtime to start them.
Each node also runs kube-proxy. It sets up network rules, so traffic sent to a Service reaches one of the right pods.
Watch. Decide. Act.
More in this series
1:30What does etcd do?
etcd as the Kubernetes database: keys, leader election, Raft quorum, watches and backups.
1:09How the scheduler works
How kube-scheduler picks a node for a pod: filtering, scoring, binding, and how to influence it.
1:21Controllers and reconciliation
The control loop at the heart of Kubernetes: desired vs actual state, Deployments, ReplicaSets and the kubelet.