https://wiki.quizz.vn/ 2026-06-26T17:45:54+00:00 https://wiki.quizz.vn/ https://wiki.quizz.vn/lib/exe/fetch.php?media=wiki:dokuwiki.svg text/html 2026-05-31T02:59:47+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:api_server&rev=1780196387&do=diff API Server The API Server is the entry point of Kubernetes. --- What it does * Accepts kubectl commands * Validates requests * Updates cluster state * Communicates with etcd (database) --- Example When you run: kubectl apply -f deployment.yaml text/html 2026-05-31T03:06:28+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:apiversion&rev=1780196788&do=diff apiVersion apiVersion defines which version of the Kubernetes API you are using. --- Why it matters Kubernetes evolves over time: * Features change * APIs are updated * Some versions are deprecated So you must specify the correct version. text/html 2026-05-31T02:57:32+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:architecture&rev=1780196252&do=diff Cluster Architecture Kubernetes cluster architecture is the overall design of how Kubernetes is built. A cluster is split into two main parts: * Control Plane (brain) * Worker Nodes (workers) --- Simple flow User request ↓ API Server (Control Plane) ↓ Scheduler decides node ↓ Worker Node runs Pod text/html 2026-05-31T02:48:11+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:cluster_model&rev=1780195691&do=diff Cluster Model A Kubernetes cluster is a group of machines that work together to run applications. It is made of: * Control Plane (brain) * Worker Nodes (workers) * Pods (applications) --- 1. Control Plane The Control Plane is the brain of Kubernetes text/html 2026-05-31T13:40:36+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:commands&rev=1780234836&do=diff Kubernetes kubectl Commands Guide This guide covers the most commonly used Kubernetes commands, explanations, and examples. Cheat Sheet Category Command Purpose Cluster `kubectl cluster-info` Show cluster information Cluster `kubectl version` text/html 2026-05-31T02:57:58+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:control_plane&rev=1780196278&do=diff Control Plane The Control Plane is the brain of Kubernetes. It manages the entire cluster. --- What it does * Decides where pods run * Monitors cluster health * Ensures desired state is always maintained * Handles scaling and recovery --- text/html 2026-05-31T03:02:45+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:deployment&rev=1780196565&do=diff Deployment A Deployment manages Pods and ensures they run correctly. --- What it does * Creates Pods * Maintains number of replicas * Handles updates (rolling update) * Supports rollback --- Example You define: replicas: 3 image: nginx text/html 2026-06-12T23:22:12+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:introduction&rev=1781306532&do=diff What is Kubernetes Kubernetes is a system that runs and manages containerized applications automatically. Instead of manually running containers, Kubernetes: * Starts them * Stops them * Restarts them when they fail * Scales them up or down text/html 2026-05-31T04:07:39+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:kind&rev=1780200459&do=diff Kubernetes ''kind'' Field — Complete Guide Overview In Kubernetes, every resource manifest (written in YAML or JSON) must declare four top-level fields: apiVersion: apps/v1 kind: Deployment metadata: name: my-app spec: ... The kind field tells Kubernetes text/html 2026-05-31T02:59:10+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:kubelet&rev=1780196350&do=diff Kubelet Kubelet is an agent running on every worker node. --- What it does * Receives instructions from API Server * Starts and stops containers * Ensures pods are running correctly * Reports node status back to Control Plane --- Example text/html 2026-05-31T03:07:35+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:metadata&rev=1780196855&do=diff metadata metadata contains information about the Kubernetes object. It does NOT define behavior — only identity and labels. --- Common fields * name → unique object name * namespace → where it belongs * labels → tags for selection text/html 2026-05-31T03:04:24+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:namespace&rev=1780196664&do=diff Namespace A Namespace is a way to organize Kubernetes resources inside a cluster. --- Why it exists Without namespaces: * Everything is in one big space * Hard to manage large systems With namespaces: * You can separate environments and teams text/html 2026-05-31T03:01:28+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:objects&rev=1780196488&do=diff Core Kubernetes Objects Kubernetes is built around a set of core objects that define how applications run. The most important ones are: * Pod * Deployment * ReplicaSet * Service * Namespace Each object has a specific role in running and managing applications. text/html 2026-05-31T03:02:05+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:pod&rev=1780196525&do=diff Pod A Pod is the smallest unit in Kubernetes. It represents one running instance of your application. --- What a Pod contains * One or more containers * Shared network (same IP) * Shared storage (optional) --- Example A simple web app: text/html 2026-05-31T03:03:21+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:replicaset&rev=1780196601&do=diff ReplicaSet A ReplicaSet ensures a specific number of Pods are running. --- What it does * Keeps N copies of a Pod running * Replaces failed Pods automatically --- Example replicas: 3 If one Pod crashes: Before: 3 pods After: 3 pods (1 recreated) text/html 2026-05-31T03:00:36+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:scheduler&rev=1780196436&do=diff Scheduler The Scheduler decides which node runs a pod. --- How it works When a new pod is created: 1. Scheduler sees the pod request 2. Checks all available nodes 3. Evaluates CPU, memory, constraints 4. Picks the best node 5. Assigns the pod --- text/html 2026-05-31T03:03:45+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:service&rev=1780196625&do=diff Service A Service provides a stable network endpoint to access Pods. --- Why needed Pods are unstable: * IP changes when restarted * Pods can be recreated anytime Service solves this problem by providing: * Stable DNS name * Stable IP inside cluster text/html 2026-05-31T03:07:55+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:spec&rev=1780196875&do=diff spec spec defines the desired state of the object. This is the most important part of any Kubernetes YAML. --- What it contains Depends on the object: * Pod → containers * Deployment → replicas + pod template * Service → ports + selector text/html 2026-05-31T02:47:35+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:why_k8s&rev=1780195655&do=diff Why Kubernetes Exists Kubernetes exists to solve real production problems when running containers at scale. --- 1. Manual container management is hard Example: You run 10 Docker containers manually. Problems: * One crashes → you must restart it text/html 2026-05-31T02:58:39+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:worker_nodes&rev=1780196319&do=diff Worker Nodes Worker Nodes are the machines that run your applications. --- What runs on a node * Pods (your applications) * kubelet * container runtime (Docker/containerd) * kube-proxy --- Example Node 1 → nginx Pod Node 2 → api Pod Node 3 → database Pod text/html 2026-05-31T03:06:08+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.quizz.vn/doku.php?id=k8s:core:yaml_basics&rev=1780196768&do=diff YAML Structure in Kubernetes Kubernetes uses YAML files to describe what you want the cluster to create. Instead of writing code, you declare the desired state. --- Basic structure Every Kubernetes YAML usually has 4 main parts: * apiVersion