DevOps Classroom notes 12/Feb/2025

Primary Workload of K8s = Pod

• Pod is an atomic unit of k8s which contains Containers
• Pod will have containers
• In k8s every resource which we create needs a name

Writing Pod Manifests

• Most of the k8s manifests have 4 sections (apiVersion, kind, metadata, spec) which will represent resource and desired state and there will a 5 section (status) which represents status (generated)
• Navigate to Apireference
  • 1.32
  • 1.31
• Lets create an nginx pod i.e. pod with nginx container in it

apiVersion: v1
kind: Pod
metadata:
  name: nginx-pod
spec:
  containers:
    - name: nginx
      image: nginx:latest

• Lets create an pod i.e. pod with httpd container in it

apiVersion: v1
kind: Pod
metadata:
  name: httpd-pod
spec:
  containers:
    - name: httpd
      image: httpd:latest

• Now lets look at some useful kubectl commands

# Watch
kubectl get pods -w
# get more info
kubectl get pods -o wide
# describe resource
kubectl describe pod nginx-pod
# Get the the output in yaml format
kubectl get pod nginx-pod -o yaml

• I want to run the following containers give me docker commands
  • alpine container with runs for 1 day docker run -d --name alptest alpine sleep 1d
  • mysql with root password, user , password and database docker run -d --name mysqltest -e MYSQL_ROOT_PASSWORD=test123 mysql:9
• Manifest for alpine

---
apiVersion: v1
kind: Pod
metadata:
  name: alptest-pod
spec:
  containers:
    - name: alptest
      image: alpine
      args:
        - sleep
        - 1d

• Manifest for mysql

apiVersion: v1
kind: Pod
metadata:
  name: mysql-test
spec:
  containers:
    - name: mysql
      image: mysql:9
      env:
        - name: MYSQL_ROOT_PASSWORD
          value: admin123
        - name: MYSQL_USER
          value: ltdevops
        - name: MYSQL_PASSWORD
          value: ltdevops
        - name: MYSQL_DATABASE
          value: ltapps

• Running commands in the container belonging to a Pod

kubectl exec <pod-name> -- <command>
kubectl exec -it <pod-name> -- <shell>