DevOps Classroom Series – 19/Nov/2020

Kubernetes Networking Model (KNM)

  • KNM requirements are
    • all pods can communicate with all other pods without using NAT
    • all Nodes can communicate with all Pods without NAT
    • the IP that Podsees itself is the same IP that other see it as
  • Lets understand the following
    • Container to Container networking
    • Pod-to-Pod Networking
    • Pod-to-svc networking
    • Internet to SVC networking

Container to Container Networking

  • Preview

Pod to Pod Networking

  • Both Pods in Same Node Preview
  • Pods on different nodes Preview
  • Pod to Service IP Address Preview

Health Checks of Pod

  • When we run our application in k8s, it is kept alive using process health check.
  • However in most cases a simple process might not be enough
    • process has deadlocked and unable to serve requests (process check will return as application is health)
  • To address this, k8s introduced health checks for application liveness
  • Liveness Probe: This probe checks for application specific logic to verify that the application is still running
  • Containers that fail liveness probe will be restarted.
  • Readiness probe describes when a container is ready to serve user requests. Containers that fail readiness check are removed from service (load balancers)
  • Refer Here for the liveness probe.

K8s in the Cloud as a service

  • Azure Kubernetes Service (AKS)
  • AWS Elastic Kubernetes Service (EKS)

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