How to use PersistentVolume for MySQL data in Kubernetes - mysql

Question

I am developing database environment on Minikube.
I'd like to persist MySQL data by PersistentVolume function of Kubernetes.
However, an error will occur when starting MySQL server and will not start up, if hostPath specified /var/lib/mysql(MySQL data directory).
kubernetes-config.yaml
apiVersion: v1
kind: PersistentVolume
metadata:
name: nfs001-pv
labels:
app: nfs001-pv
spec:
capacity:
storage: 1Gi
accessModes:
- ReadWriteMany
persistentVolumeReclaimPolicy: Retain
mountOptions:
- hard
nfs:
path: /share/mydata
server: 192.168.99.1
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: nfs-claim
spec:
accessModes:
- ReadWriteMany
resources:
requests:
storage: 1Gi
storageClassName: ""
selector:
matchLabels:
app: nfs001-pv
---
apiVersion: apps/v1beta2
kind: Deployment
metadata:
name: sk-app
labels:
app: sk-app
spec:
replicas: 1
selector:
matchLabels:
app: sk-app
template:
metadata:
labels:
app: sk-app
spec:
containers:
- name: sk-app
image: mysql:5.7
imagePullPolicy: IfNotPresent
env:
- name: MYSQL_ROOT_PASSWORD
value: password
ports:
- containerPort: 3306
volumeMounts:
- mountPath: /var/lib/mysql
name: mydata
volumes:
- name: mydata
persistentVolumeClaim:
claimName: nfs-claim
---
apiVersion: v1
kind: Service
metadata:
name: sk-app
labels:
app: sk-app
spec:
type: NodePort
ports:
- port: 3306
nodePort: 30001
selector:
app: sk-app
How can I launch it?
-- Postscript --
When I tried "kubectl logs", I got following error message.
chown: changing ownership of '/var/lib/mysql/': Operation not permitted
When I tried "kubectl describe xxx", I got following results.
kubectl describe pv:
Name: nfs001-pv
Labels: app=nfs001-pv
Annotations: pv.kubernetes.io/bound-by-controller=yes
StorageClass:
Status: Bound
Claim: default/nfs-claim
Reclaim Policy: Retain
Access Modes: RWX
Capacity: 1Gi
Message:
Source:
Type: NFS (an NFS mount that lasts the lifetime of a pod)
Server: 192.168.99.1
Path: /share/mydata
ReadOnly: false
Events: <none>
kubectl describe pvc:
Name: nfs-claim
Namespace: default
StorageClass:
Status: Bound
Volume: nfs001-pv
Labels: <none>
Annotations: pv.kubernetes.io/bind-completed=yes
pv.kubernetes.io/bound-by-controller=yes
Capacity: 1Gi
Access Modes: RWX
Events: <none>
kubectl describe deployment:
Name: sk-app
Namespace: default
CreationTimestamp: Tue, 25 Sep 2018 14:22:34 +0900
Labels: app=sk-app
Annotations: deployment.kubernetes.io/revision=1
Selector: app=sk-app
Replicas: 1 desired | 1 updated | 1 total | 0 available | 1 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy: 25% max unavailable, 25% max surge
Pod Template:
Labels: app=sk-app
Containers:
sk-app:
Image: mysql:5.7
Port: 3306/TCP
Environment:
MYSQL_ROOT_PASSWORD: password
Mounts:
/var/lib/mysql from mydata (rw)
Volumes:
mydata:
Type: PersistentVolumeClaim (a reference to a PersistentVolumeClaim in the same namespace)
ClaimName: nfs-claim
ReadOnly: false
Conditions:
Type Status Reason
---- ------ ------
Available False MinimumReplicasUnavailable
Progressing True ReplicaSetUpdated
OldReplicaSets: <none>
NewReplicaSet: sk-app-d58dddfb (1/1 replicas created)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal ScalingReplicaSet 23s deployment-controller Scaled up replica set sk-app-d58dddfb to 1

Answer 1

Volumes look good, so looks like you just have a permission issue on the root of your nfs volume that gets mounted as /var/lib/mysql on your container.
You can:
1) Mount that nfs volume using nfs mount commands and run a:
chmod 777 . # This gives rwx to anybody so need to be mindful.
2) Run an initContainer in your deployment, similar to this:
apiVersion: apps/v1beta2
kind: Deployment
metadata:
name: sk-app
labels:
app: sk-app
spec:
replicas: 1
selector:
matchLabels:
app: sk-app
template:
metadata:
labels:
app: sk-app
spec:
initContainers:
- name: init-mysql
image: busybox
command: ['sh', '-c', 'chmod 777 /var/lib/mysql']
volumeMounts:
- mountPath: /var/lib/mysql
name: mydata
containers:
- name: sk-app
image: mysql:5.7
imagePullPolicy: IfNotPresent
env:
- name: MYSQL_ROOT_PASSWORD
value: password
ports:
- containerPort: 3306
volumeMounts:
- mountPath: /var/lib/mysql
name: mydata
volumes:
- name: mydata
persistentVolumeClaim:
claimName: nfs-claim
accessModes:
- ReadWriteMany