how to migrate VM data from a disk to a Kubernetes cluster?
I have a VM with three disks attached mounted to it, each having data that needs to be migrated to a Kubernetes cluster to be attached to database services in statefulset.
This link https://cloud.google.com/kubernetes-engine/docs/how-to/persistent-volumes/preexisting-pd does give me the way. But don't know how to use it or implement it with statefulsets so that one particular database resource (like Postgres) be able to use the same PV(created from one of those GCE persistent disks) and create multiple PVCs for new replicas.
Is the scenario I'm describing achievable? If yes how to implement it?
apiVersion: elasticsearch.k8s.elastic.co/v1
kind: Elasticsearch
metadata:
name: elasticsearch
spec:
version: 6.8.12
http:
tls:
selfSignedCertificate:
disabled: true
nodeSets:
- name: default
count: 3
config:
node.store.allow_mmap: false
xpack.security.enabled: false
xpack.security.authc:
anonymous:
username: anonymous
roles: superuser
authz_exception: false
volumeClaimTemplates:
- metadata:
name: elasticsearch-data
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 50Gi
storageClassName: managed-premium
StatefulSet is a preference for manually creating a PersistentVolumeClaim. For database workloads that can't be replicated, you can't set replicas: greater than 1 in either case, but the PVC management is valuable. You usually can't have multiple databases pointing at the same physical storage, containers or otherwise, and most types of Volumes can't be shared across Pods.
Postgres doesn't support multiple instances sharing the underlying volume without massive corruption so if you did set things up that way, it's definitely a mistake. More common would be to use the volumeClaimTemplate system so each pod gets its own distinct storage. Then you set up Postgres streaming replication yourself.
Refer to the document on Run a replicated stateful application and stackpost for more information.