K8s storage:

• Container are ephameral. when container will restart , everthing will be wirte in file system it will be lost.
• K8s Storage sloved two problem

1. Presistance: data will survives container restart and pod rescheduling.
2. Sharing: multiple container can share data.

Storage building blocks:

Volume:

• scope level is pod
• directly access container in pod

volume 
  - name: demo 
    path: /data/mysql 

Volume ==> create and name volume ==> POD will use it 

PersistentVolume (PV):

• scope level is cluser
• A piece of storage created/provisioned by admin or dynamically

PersistentVolume Claim (PVc):

• scope level is namespace
• User request storage (required by container)

Storage class:

• scope level is cluster
• Define storage class and enable dynamic provisioning

EX: local-path, NFS

CSI Drivers:

• CSI Stands for Container Storage Interface
• scope level is cluser
• plugin like EBS, AZure DIsk, NFS…etc

Ephameral Vloume types:

• these are live and die with the pod

emptyDir

• An Empty dir will create when pod started . Delete dir when pod get deleted/removed
• Use-cases:
  • scratch space (every time need new space storage)
  • Cache
  • Sharing file between sidecar container and main container.

# create empty vloume
volumes:
 - name: shared
   emptyDir: {}

## Mount volume
volumeMounts:
 - name: shared
   mountpath: /data

Ram-base variant

volumes:
 - name: cache
   emptyDir: {}
      medium: Memory
      sizeLimit: 256Mi

Sample yaml for emptyDir volume:

apiVersion: apps/v1
kind: Deployment

metadata:
  name: recreate-deployment-app
  labels:
    app: apache2

spec:
  replicas: 2

  selector:
    matchLabels:
      app: apache2

  strategy:
    type: Recreate

  template:
    metadata:
      labels:
        app: apache2

    spec:
      initContainers:
        - name: download-template
          image: alpine:latest
          command:
            - sh
            - -c
            - |
              apk add --no-cache wget unzip
              wget -O /tmp/templatemo_589_lugx_gaming.zip \
                https://templatemo.com/tm-zip-files-2020/templatemo_589_lugx_gaming.zip
              unzip /tmp/templatemo_589_lugx_gaming.zip \
                -d /usr/local/apache2/htdocs/
              cp /usr/local/apache2/htdocs/templatemo_589_lugx_gaming/* /usr/local/apache2/htdocs/
              rm -rf /usr/local/apache2/htdocs/templatemo_589_lugx_gaming
          volumeMounts:
            - name: apache2-html
              mountPath: /usr/local/apache2/htdocs/

      containers:
        - name: apache2
          image: httpd:2
          ports:
            - containerPort: 80

          volumeMounts:
            - name: apache2-html
              mountPath: /usr/local/apache2/htdocs/

      volumes:
        - name: apache2-html
          emptyDir: {}

---
apiVersion: v1
kind: Service
metadata:
  name: nodeport-service-apache2
  labels:
    app: apache2
spec:
  type: NodePort
  selector:
    app: apache2  
  ports:
    - protocol: TCP
      port: 80
      targetPort: 80
      nodePort: 30010

Task:

1. create similar way volume emptyDir
2. used main image nginx image and create init container download sample template from https://templatemo.com
3. deploy and valiadte endpoint

FROM nginx
COPY static-html-directory /usr/share/nginx/html