K8s

• Open source Container Orchestration tool
• by Google
• Helps manage containerized applications in different deployment environments

Orchestration tool offers:

• High Availability, no downtime
• Scalability, high performance
• Disaster recovery, backup/restore

Used terminology

https://kubernetes.io/docs/reference/glossary

K8s	Kubernetes
CNCF	Cloud Native Computing Foundation
NetPol	Network Policies
PV	Persistent Volumes
PVC	Persistent Volume Claims
CSI	Container Storage Interface
CNI	Container Network Interface
CI/CD	Continuous Integration & Continuous Deployment
RBAC	Role Based Access Control
OCI	Open Container Initiative
CRI	Container Runtime Interface
SMI	Service Mesh Interface
SLO	Service Level Objectives
SLI	Service Level Indicators
SLA	Service Level Agreements

Components

• Node
  • Control Plane Node (Master Node)
    • API server: entry point to K8s cluster. UI/API/CLI
    • Controller Manager: keeps track of what’s happening in the cluster
    • Scheduler: ensure Pods placement
    • etcd: K8s backing store. Key/Value storage. holds the current status of any K8s component
  • Worker Node

• Pod:
  • Smallest unit & is ephemeral
  • Abstraction over container
  • 1 application per Pod
  • Gets its own IP

• Service:
  • Permanent static IP
  • Lifecycle of Pod and Service not connected

• Volume:
  • K8s doesn’t manage data persistence
  • local or remote

• Ingress

• ConfigMap:
  • External configuration of your application (URLs)
  • for non-confidential data only!

• Deployment:
  • Blueprint for the Pod
  • use the same Service
  • DB can’t be replicated via Deployment!
  • for stateLESS apps

• Secret:
  • like ConfigMap
  • in Base64 encoded format

• StatefulSet:
  • for stateFUL apps or databases

• DaemonSet