CAPI Cluster APIs

Kubernetes uses objects and components to define, manage, and operate containerized workloads and infrastructure at scale.kubernetes+4

Main Kubernetes Objects

Kubernetes objects are persistent entities representing the desired state of cluster resources and workloads.kodekloud+2

• Pod: The basic unit hosting one or more containers, typically grouped for tight coupling or fast communication; pods are ephemeral.geeksforgeeks+1
• Deployment: Manages stateless application lifecycles, handling desired state, scaling, updates, and rolling changes via ReplicaSets.learning.sap+1
• Service: Exposes a pod or group of pods on a network, abstracting internal pod IPs and providing stable endpoints for communications.learning.sap
• StatefulSet: Controls stateful applications, ensuring ordered deployment, scaling, and persistence of identifiers across pod restarts.asvin
• DaemonSet: Ensures a copy of a pod runs on all or certain nodes, suitable for cluster-level tasks like log collection or monitoring.asvin
• Job/CronJob: Handles batch or scheduled tasks, ensuring pods start and complete the assigned work.asvin
• ConfigMap & Secret: Allows passing configuration data and sensitive information (like passwords) to workloads securely.asvin

Kubernetes Core Components

The cluster architecture is split between control plane and worker node components, each responsible for distinct functions in orchestration and management.acecloud+2

Control Plane Components

• API Server: The central interface for all cluster operations, validating REST requests and managing communication between components.spot+1
• etcd: Distributed key-value store used as Kubernetes’ backing store for all cluster data and state.acecloud
• Controller Manager: Runs background controllers that reconcile resource status, manage replicas, garbage collect, and handle jobs.acecloud
• Scheduler: Assigns workloads to nodes based on resource availability and constraints.acecloud

Worker Node Components