Kubernetes Internals Deep Dive Summary Pt2

If you haven’t yet, check the first part here

K8 Architecture Summary Pt2

What happens when we submit a pod manifest to the API server?

Before any event, the Controler Manager, Scheduler and the Kubelet are in “watching mode” waiting for a new event for their respective resources types in the API Server


Deployment manifest created

Now you executed the command kubectl create -f deployment.yaml

This happens next:

  1. The API Server verifies the Deployment specifications
  2. Stores it in etcd
  3. Returns a response to kubectl

After the following chain of events takes place


What a running pod is?

When we run kubectl run nginx --image=nginx a few interesting things happens:

  1. Nginx container Running
  2. Pod Infrastructure Container (pause container) running


The Pause Container

The pause container is the container that holds all containers in the pod together. All containers in the pod share the same network and Linux namespaces, the Pod Infrastructure Container holds all these namespaces.