CONTAINERS / A CONCEPT NOTE
Kubernetes
orchestrating containers at scale
Overview · mechanism
pitfall · examples
01 / THE SHORT VERSION
The idea in a few sentences.
A cluster of nodes (servers) managed by a control plane. You declare desired state in YAML — Deployment, Service, ConfigMap — and the control plane drives actual state toward it. Pods are the smallest deployable unit: one or more containers sharing a network namespace.
02 / FOLLOW THE MECHANISM
How a deployment rolls out
You
run
kubectl apply -f deploy.yamlwhich sends the manifest to the API server.API server
validates the manifest and stores it in etcd (the cluster's source of truth).
Controller manager
notices the Deployment's desired state doesn't match actual state and creates a ReplicaSet.
Scheduler
picks nodes for each new Pod based on resource requests, taints, and affinity rules.
Kubelet
on each node receives the Pod spec and tells the container runtime (containerd) to pull images and start containers.
04 / COMMAND NOTES
Read the command, then the result.
Inspect the flags and arguments before trying an example. Snippets can need local setup, replacement values, or resources in your own environment.
list every pod across all namespaces
kubectl get pods -Asee events, conditions, and container status
kubectl describe pod POD_NAME05 / CHECK YOURSELF
Could you explain Kubernetes to a teammate?
Try it out loud in two sentences: what it is, and the one detail that changes the picture. If you stall, the gap is the part to reread.
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