Kubernetes: An Orchestrator for Containerized Workloads

Conceptual Overview

• Analogy: Kubernetes as an orchestra conductor, Docker containers as musicians.
  • App Example: Robinhood during market hours - needs to handle millions of trades.

Core Components

• Cluster: The system deployed on Kubernetes.
• Control Plane: The brain of the operation.
  • Manages the cluster via an API server (handles internal/external requests).
  • Contains etcd, a key-value database for cluster information.
• Nodes: Worker machines managed by the Control Plane.
  • Runs kubelet, an app that communicates with the Control Plane.
• Pods: Smallest deployable unit in Kubernetes (group of containers running together).

Scaling and Availability

• Horizontal Scaling: Adds more nodes to the cluster as workload increases.
• High Availability: Achieved via maintaining a Replica Set (set of ready-to-go pods/containers).

Developer Workflow

• Define objects in YAML files to describe the desired state of the cluster.
  • Example: An nginx deployment with a replica set of 3 pods.
  • Spec Field: Defines containers, volumes, ports, etc.

Additional Features

• Networking
• Secret Management
• Persistent Storage

Summary

• Kubernetes manages infrastructure to handle variable workloads efficiently.
• Automates scaling, networking, storage, and ensures high availability.

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