DevOps Classroom notes 21/Jun/2026

Pods

• Pod is an atomic unit of creation in k8s
• Think of Pod as a small package with one or more containers in it
• Every pod will get an unique ip in the k8s cluster
• Containers in the Pod have shared resources i.e.
  • shared network
  • shared storage

• Consider typical application
  
• If we have to run this in containers, we run each component in a container
  
• When it comes it pods consider the following
  
• Each Pod can be scaled horizontally or vertically with other k8s workloads
• When pod has more that one containers, the primary container is referred as maincar and all the other containers are referred as sidecars

Interaction with k8s cluster

• To interact with k8s we can use any client which can sent http(s) requests. k8s gives two simple options
  • kubectl: A cli tool to interact with k8s api-server
  • client libraries: Refer Here
    
• k8s api-server is by default https and the default configuration of k8s requires client to be authorized to communicate with k8s cluster.
• Note: when we installed kubeadm, on the master node we have a file called as kube-config file ~/.kube/config which contains certificate data and api-server urls to connect

kubectl

• kubectl is a cli and it can be installed directly on any system
• Refer Here for installation
• k8s allows to be interacted from kubectl in two ways
  • with commands (imperative): we construct a command based on what we want
    
  • with manifest files (declarative): we create a yaml file based on what we want and apply the file
    
    
• We would use declartive approach for regular activities.

Lets play with pods

• Today lets focus on imperative way of creating Pods

Create a pod with a name web1 with httpd container in it

• syntax

kubectl run <paramters> <name-of-pod>

• Example

kubectl run --image httpd web1

• To view the pods

kubectl get pods

• To view the pods with more info

kubectl get pods -o wide

• To delete the pod

kubectl delete pod <name>

• We can create pod and exec into contianer
  

Activity

• Create two pods
  • web1 => nginx
  • web2 => httpd
• execute the command whoami
• delete the pods
• note: use killercoda

Intro to Writing k8s manifests

• Manifest in k8s is where we express a desired state in the yaml form.
• k8s gives an api reference using which writing yaml files is easier Refer Here
• Watch video