Kubernetes Cheatsheet

Kubernetes Basics

Use this Kubernetes reference while you build software engineering projects, review code for technical interview prep, or polish examples for a software engineer resume.

Core Concepts

Kubernetes (k8s) orchestrates containerized workloads across a cluster of machines.

Term	What it is
Node	A machine (VM or bare metal) in the cluster
Pod	Smallest deployable unit; one or more containers sharing a network/storage
Deployment	Manages replicated Pods; handles rollouts and rollbacks
Service	Stable network endpoint in front of a set of Pods
Namespace	Virtual cluster; isolates resources by team/environment
ConfigMap	Non-secret key-value config injected into Pods
Secret	Base64-encoded sensitive config (passwords, tokens)
PersistentVolume	Cluster-level storage resource
Ingress	HTTP/HTTPS routing rules into the cluster
StatefulSet	Like Deployment but for stateful apps (stable identity, ordered rollout)
DaemonSet	Runs one Pod per Node (logging agents, node monitors)
Job / CronJob	Run-to-completion tasks / scheduled tasks

Control Plane vs. Data Plane

Control Plane                  Data Plane (Worker Nodes)
─────────────────────          ──────────────────────────
kube-apiserver   ◄──REST──►   kubelet  (runs Pods)
etcd             (state)       kube-proxy (iptables / IPVS)
kube-scheduler                 container runtime (containerd)
kube-controller-manager

API Versions

Kind	API Group	apiVersion
Pod, Service, ConfigMap, Secret	core	`v1`
Deployment, ReplicaSet, DaemonSet, StatefulSet	apps	`apps/v1`
Ingress	networking.k8s.io	`networking.k8s.io/v1`
HorizontalPodAutoscaler	autoscaling	`autoscaling/v2`
CronJob	batch	`batch/v1`
NetworkPolicy	networking.k8s.io	`networking.k8s.io/v1`

Minimal Manifest Skeleton

Every Kubernetes manifest shares the same four top-level fields:

apiVersion: <group>/<version>   # e.g. apps/v1
kind: <Kind>                    # e.g. Deployment
metadata:
  name: my-resource
  namespace: default            # omit to use current context namespace
  labels:
    app: my-app
spec:
  # kind-specific spec

Labels and Selectors

Labels are arbitrary key/value pairs; selectors filter on them.

# on the resource
metadata:
  labels:
    app: api
    env: prod
    version: "2.1"

# filter with kubectl
kubectl get pods -l app=api
kubectl get pods -l app=api,env=prod
kubectl get pods -l 'env in (prod,staging)'
kubectl get pods -l 'version notin (1.0)'

Annotations

Non-identifying metadata (larger values, tool hints, build info):

metadata:
  annotations:
    kubernetes.io/change-cause: "bump image to v2.1"
    prometheus.io/scrape: "true"
    prometheus.io/port: "9090"

Resource Requests and Limits

Set on every container — prevents noisy-neighbor issues and enables scheduling.

resources:
  requests:
    cpu: "250m"      # 0.25 core
    memory: "256Mi"
  limits:
    cpu: "1"
    memory: "512Mi"

Rule of thumb: set requests = typical usage, limits = spike ceiling. CPU is throttled at the limit; memory OOM-kills the container.

Quality of Service Classes

QoS Class	Condition
Guaranteed	`requests == limits` for every container
Burstable	`requests < limits` for at least one container
BestEffort	No requests or limits set

Eviction order under memory pressure: BestEffort → Burstable → Guaranteed.

Context and Cluster Setup

kubectl config get-contexts              # list all contexts
kubectl config current-context           # show active context
kubectl config use-context my-cluster    # switch context
kubectl config set-context --current --namespace=staging   # set default namespace