Kubernetes

Terminology

  • Nodes: This are virtual or physical machine with actual resources, like CPU and RAM.

  • Kubernetes cluster: group of nodes either physical or virtual machines that contain one master node and any number of worker nodes.

  • Pods: one or more containers that share storage and network resources.

  • Namespace : gives privacy to resources. keeping their secrets secluded from other servi

  • Services : A way to expose an application running on a set of pods as a network service.

Types Of Kubernetes Services:

  • ClusterIP : service is only reachable within the cluster, pods within the cluster can use this as an IP for communication

  • LoadBalancer : A single point of entry outside the cluster

  • NodePort : Expose the port within the cluster to outside service

  • ExternalName : maps a service to a domain name

Kubectl

Get all pods within a namespace

kubectl get pods -n <namespace>

Get all services within a namespace

kubectl get svc -n <namespace>

What is containerd.sock specifically?

This file (often located at /run/containerd/containerd.sock) is where clients connect to containerd.

For example:

  • Docker uses it to tell containerd: “Hey, pull this image” or “Run this container.”

  • Kubernetes (via CRI plugin) uses it to manage pods.

crictl -r unix://<path_to_containerd>/containerd.sock images

Video

https://madhuakula.com/kubernetes-goat/docs/learning-kubernetes