k8s.volumes.md

K8s Volumes

How to persist data in Kubernetes using Volumes.

- Persistent Volume, Persistent Volume Claim, Storage Class 
- Storage that doesn't depend on the pod lifecycle. 
- Storage must be available on all nodes.
- Storage needs to survive even if cluster crashes. 
- Another use case is to write/reads session data

Persistent Volume

- cluster resource
- created via Yaml file
	 apiVersion: v1
	 kind: PersistentVolume
	 metadata:
	   name: 
	 spec:
	   capacity 

- needs actual physical storage, like local disk, nfs server, or cloud storage
- Where does this storage come from and who makes it available to the cluster?
- What type of storage do you need?
- external plugin to your cluster

- Pesistent volume outside of the namespaces, accessible to the whole cluster
- local vs. Remote volume types 

Who creates Persistent Volume and when

- Storage resources is provisioned by Admin
- Create the PV components from storage backends
- Application has to claim the Persistent Volume (PVC)
	kind: PersistentVolumeClaim
- Use PVC in the Pods configuration
	apiVersion: v1 
	kind: Pod
	metadata: 
	  name: mypod
	spec:
	  containers:
        - names: myfrontend
          image: nginx
	  volumes:
	  - name
	  	persistentVolumeClaim:
- Claims must be in the same namespace! 
- Volume is mounted into the Pod
- Volume is mounted into Container

ConfigMap and Secret

- local volume
- not created via PV and PVC
- managed by Kubernetes

Storage class

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata: