I have created the following PV, PVc and pod .
For the Persistent volume i have chosen the /opt directory of the host machine as the volume.
After creating the pod i logged in inside the pod and created a file text.txt under /etc/lala directory ,and came out of the pod.
Question) Will this file, text.txt, be now available in the /opt directory of the host machine ?
Following is the Persistent Volume yaml file.
apiVersion: v1
kind: PersistentVolume
metadata:
name: mypv
spec:
accessModes:
- ReadWriteMany
capacity:
storage: 1G
storageClassName: normal
hostPath:
path: /opt
Following is the Persistent Volume claim yaml file
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: mypvc
spec:
accessModes:
- ReadWriteMany
storageClassName: normal
resources:
requests:
storage: 1G
Following is the Pod yaml file .
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: null
labels:
run: nginx
name: nginx
spec:
containers:
- image: nginx
name: nginx
ports:
- containerPort: 80
resources: {}
volumeMounts:
- name: myvol
mountPath: /etc/lala
dnsPolicy: ClusterFirst
restartPolicy: Always
volumes:
- name: myvol
persistentVolumeClaim:
claimName: mypvc
status: {}
In order to understand and debug your code, could you please format it a bit better. Use the </> key to generate a code block. This will
Help preserve:
- proper indentation
- dashes won't turn into ° or ▪️
- Quotes won't turn into smart quotes (which don't work)
Thank you Sir for the reply.
I tried and every thing worked well.
only when i created the text.txt file inside the pod using the command " echo hello > text.txt " the file was created but after logging out of the pod when i checked the /opt directory of my host machine the file was not there.
Where can i find the same.
All this dots, circles and squares are dashes(-). This platform is automatically converting dashes to dots and circles.
You can also see the yaml file in the following git repo :
Deepakranjanmishra/DevOps_Class/tree/main/MY_KUBERNETES/PV-PVC
Following is the Pod yaml file .
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: null
labels:
run: nginx
name: nginx
spec:
containers:
- image: nginx
name: nginx
ports:
- containerPort: 80
resources: {}
volumeMounts:
- name: myvol
mountPath: /etc/lala
dnsPolicy: ClusterFirst
restartPolicy: Always
volumes:
- name: myvol
persistentVolumeClaim:
claimName: mypvc
status: {}
Sir i have replied back in the email. Please take a look at the email.
I haven’t received mail from you, sorry.
Here’s a tutorial how to enter code correctly in Discourse, the forum software we’re using. I know it’s a bother, but it’s a skill worth learning.
If you press the button indicated by Rob, you can paste your code correctly, like this
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: null
labels:
run: nginx
name: nginx
spec:
containers:
- image: nginx
name: nginx
ports:
- containerPort: 80
resources: {}
volumeMounts:
- name: myvol
mountPath: /etc/lala
dnsPolicy: ClusterFirst
restartPolicy: Always
volumes:
- name: myvol
persistentVolumeClaim:
claimName: mypvc
status: {}
I have tried your code from the git repo and it does what you expect.
controlplane ~ ➜ k get po
NAME READY STATUS RESTARTS AGE
nginx 1/1 Running 0 12s
controlplane ~ ➜ k exec -it nginx -- bash
root@nginx:/# cd /etc/lala
root@nginx:/etc/lala# echo "hi" > test.txt
root@nginx:/etc/lala# ls -l
total 4
-rw-r--r-- 1 root root 3 Jun 19 05:24 test.txt
root@nginx:/etc/lala#
exit
controlplane ~ ➜ ls -l /opt
total 4
-rw-r--r-- 1 root root 3 Jun 19 05:24 test.txt
controlplane ~ ➜ cat /opt/test.txt
hi
controlplane ~ ➜
If your cluster has more than one node, then whichever node the PV binds to is where the file will end up.
1 Like
Yes i will, Thank You.
Alistair Sir has provided the solution i was asking for.
Thank you very much Sir , this was what i was trying to know.
Sir , in the end you have said " If your cluster has more than one node, then whichever node the PV binds to is where the file will end up. "
How will we know that which node has the PV binded ?
Any other such information on PV and PVC if you can kindly share.
It will be created when the PVC is claimed by the pod.
controlplane ~ ➜ k get po -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx 1/1 Running 0 8s 10.244.2.2 node02 <none> <none>
controlplane ~ ➜ k exec -it nginx -- bash
root@nginx:/# cd /etc/lala/
root@nginx:/etc/lala# touch test.txt
root@nginx:/etc/lala# ls -l
total 12
drwxr-xr-x 1 root root 4096 Apr 18 13:10 cni
drwx--x--x 4 root root 4096 Apr 18 13:10 containerd
-rw-r--r-- 1 root root 0 Jun 19 18:32 test.txt
root@nginx:/etc/lala#
exit
controlplane ~ ✖ ssh node02
Last login: Wed Jun 19 18:31:54 2024 from 192.34.45.9
node02 ~ ➜ cd /opt
node02 /opt ✖ ls -l
total 12
drwxr-xr-x 1 root root 4096 Apr 18 13:10 cni
drwx--x--x 4 root root 4096 Apr 18 13:10 containerd
-rw-r--r-- 1 root root 0 Jun 19 18:32 test.txt
node02 /opt ➜
As you can see here, there are already 2 directories on the node at /opt.
You should ideally create hostpath volumes for directories that won’t already exist on the host (like '/var/my-hostpath`), or the container can modify host files which is not necessarily what you want.
1 Like
Beautiful explanation Sir. Thanks a lot.
Deepak.
