Cheat SheetsKubernetesFundamentals

Fundamentals — Cheat Sheet

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Cheat Sheet · AiCanCode.org
Fundamentals
Kubernetes1 topicsQuick revision reference
1

What is Kubernetes & Why Orchestration?

Kubernetes (K8s) is the industry-standard container orchestrator — it runs containers across a cluster of machines, handles failures, scales workloads, and manages deployments with zero downtime.

  • ✓Kubernetes automates container placement, self-healing, scaling, and rolling deployments across a cluster.
  • ✓Control plane (apiserver, etcd, scheduler, controllers) manages desired state.
  • ✓Worker nodes run the actual workloads via kubelet + container runtime (containerd).
  • ✓kubectl communicates with the kube-apiserver using config in ~/.kube/config.
  • ✓etcd is the cluster's source of truth — a key-value store of all cluster state.
  • ✓Kubernetes reconciliation: controllers continuously compare desired state (YAML) with actual state and fix divergence.
Problems Kubernetes solves
Without Kubernetes (manual multi-host container management):

┌────────────────────────────────────────────────────────┐

│  Problems:                                             │

│  ❌ Which server do I deploy to?                       │

│  ❌ Server-1 dies → manually redeploy on Server-2      │

│  ❌ Traffic spike → manually start more containers     │

│  ❌ How do services find each other across servers?    │

│  ❌ Rolling update without downtime = complex scripts  │

│  ❌ Config and secrets management = per-server files   │

â””────────────────────────────────────────────────────────┘



With Kubernetes:

┌────────────────────────────────────────────────────────┐

│  Solutions:                                            │

│  ✅ Scheduler places containers on best-fit nodes      │

│  ✅ Controller restarts failed containers automatically │

│  ✅ HPA scales pods based on CPU/memory/custom metrics  │

│  ✅ Service DNS provides stable endpoint regardless    │

│     of which node the pod runs on                      │

│  ✅ Deployment manages rolling updates with zero down  │

│  ✅ ConfigMaps and Secrets manage config centrally     │

â””────────────────────────────────────────────────────────┘
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