Skip to main content

Persistent Volume in K8s Multinode cluster with NFS

nfs - server (10.0.1.9)
############
Amazon machine linux

# yum update
# yum install nfs-utils -y
# systemctl enable nfs-server
# systemctl start nfs-server

# mkdir -p /srv/nfs/k8sdata
# chmod -R 777 /srv/nfs/k8sdata

# vi /etc/exports

/srv/nfs/k8sdata *(rw,no_subtree_check,no_root_squash,insecure)

:wq!

# exportfs -rav

# exportfs -v
/srv/nfs/k8sdata
(rw,sync,wdelay,hide,no_subtree_check,sec=sys,insecure,no_root_squash,no_all_squash)

Now in NFS- Client:
#################

Ubuntu 16.04

# sudo apt-get update
# sudo apt-get install nfs-common
# showmount -e 10.0.1.9
Export list for 10.0.1.9:
/srv/nfs/k8sdata *

Testing
-------
# sudo mount -t nfs 10.0.1.9:/srv/nfs/k8sdata /mnt
# root@dn1:~# df -h | grep nfs
10.0.1.9:/srv/nfs/k8sdata  8.0G  1.8G  6.3G  22% /mnt

# umount /mnt

Now in the kubectl terminal issue the pv and pvc create with yamls

cat > 4-pv-nfs.yaml

apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-nfs-pv1
  labels:
    type: local
spec:
  storageClassName: manual
  capacity:
    storage: 1Gi
  accessModes:
    - ReadWriteMany
  nfs:
    server: 10.0.1.9
    path: "/srv/nfs/k8sdata"

cat > 4-pvc-nfs.yaml

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-nfs-pv1
spec:
  storageClassName: manual
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 500Mi
   
--------------------------------------
Here the catch is that, the storageClassName in pvc yaml file should be same as the storageClassName in pv yaml file:

# kubectl create -f 4-pv-nfs.yaml
persistentvolume/pv-nfs-pv1 created

# kubectl create -f 4-pvc-nfs.yaml
persistentvolumeclaim/pvc-nfs-pv1 created

ubuntu@namenode:~$ kubectl get pv,pvc
NAME                          CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                 STORAGECLASS   REASON   AGE
persistentvolume/pv-nfs-pv1   1Gi        RWX            Retain           Bound    default/pvc-nfs-pv1   manual                  4m26s

NAME                                STATUS   VOLUME       CAPACITY   ACCESS MODES   STORAGECLASS   AGE
persistentvolumeclaim/pvc-nfs-pv1   Bound    pv-nfs-pv1   1Gi        RWX            manual         6s


Now u can create a deployment with below Volume parameters:

--------------------------------------

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  labels:
    run: nginx
  name: nginx-deploy-nfs
spec:
  replicas: 1
  selector:
    matchLabels:
      run: nginx
  template:
    metadata:
      labels:
        run: nginx
    spec:
      volumes:
      - name: www
        persistentVolumeClaim:
          claimName: pvc-nfs-pv1
      containers:
      - image: nginx
        name: nginx
        volumeMounts:
        - name: www
          mountPath: /usr/share/nginx/html
       
----------------------------------------

Here the catch is , the ( -name: www ) of VolumeMounts in "containers:" section should be the same as the ( -name: www ) in the "volumes:" section.

ubuntu@namenode:~/kubernetes/yamls$ kubectl create -f 4-nfs-nginx-1.6.yaml
deployment.apps/nginx-deploy-nfs created

ubuntu@namenode:~/kubernetes/yamls$ kubectl get pods -o wide | grep nfs
nginx-deploy-nfs-6fdd5b84cc-s4qfp     1/1     Running   0          35s    10.244.1.35   dn1               

Now check in Dn1 if the nfs is mounted

root@dn1:~# df -h | grep nfs
10.0.1.9:/srv/nfs/k8sdata  8.0G  1.8G  6.3G  22% /var/lib/kubelet/pods/89523633-0a50-43c6-b13a-a96270f0c819/volumes/kubernetes.io~nfs/pv-nfs-pv1


Now expose your deployment and create the nginx-ingress resouce rule for getting this deployment from outside.

# kubectl expose deploy nginx-deploy-nfs --port 80

That is all

Cheers.

Comments

Post a Comment

Popular posts from this blog

K8s External Secrets integration between AWS EKS and Secrets Manager(SM) using IAM Role.

What is K8s External Secrets and how it will make your life easier? Before saying about External Secrets we will say about k8s secrets and how it will work. In k8s secrets we will create key value pairs of the secrets and set this as either pod env variables or mount them as volumes to pods. For more details about k8s secrets you can check my blog http://jinojoseph.blogspot.com/2020/08/k8s-secrets-explained.html   So in this case if developers wants to change the ENV variables , then we have to edit the k8s manifest yaml file, then we have to apply the new files to the deployment. This is a tiresome process and also chances of applying to the wrong context is high if you have multiple k8s clusters for dev / stage and Prod deployments. So in-order to make this easy , we can add all the secrets that is needed in the deployment, in the AWS Secret Manager and with the help of External secrets we can fetch and create those secrets in the k8s cluster. So what is K8s external Secret? It i...
Post a Comment
Read more

Password reset too simplistic/systematic issue

Some time when we try to reset the password of our user in linux it will show as simple and systematic as below: BAD PASSWORD: it is too simplistic/systematic no matter how hard password you give it will show the same. Solution: ######### Check if your password is Ok with the below command, jino@ndz~$ echo 'D7y8HK#56r89lj&8*&^%&^%#56rlKJ!789l' | cracklib-check D7y8HK#56r89lj&8*&^%&^%#56rlKJ!789l: it is too simplistic/systematic Now Create a password with the below command : jino@ndz~$ echo $(tr -dc '[:graph:]' 7\xi%!W[y*S}g-H7W~gbEB4cv,9:E:K; You can see that this password will be ok with the cracklib-check. jino@ndz~$ echo '7\xi%!W[y*S}g-H7W~gbEB4cv,9:E:K;' | cracklib-check                 7\xi%!W[y*S}g-H7W~gbEB4cv,9:E:K;: OK Thats all, Thanks.
Post a Comment
Read more

Setting /etc/hosts entries during the initial deployment of an Application using k8s yaml file

Some times we have to enter specific hosts file entries to the container running inside the POD of a kubernetes deployment during the initial deployment stage itself. If these entries are not in place, the application env variables mentioned in the yaml file , as hostnames , will not resolve to the IP address and the application will not start properly. So to make sure the /etc/hosts file entries are already there after the spin up of the POD you can add the below entries in your yaml file. cat > api-deployment.yaml apiVersion: apps/v1 kind: Deployment metadata: spec:   template:     metadata:     spec:       volumes:       containers:       - image: registryserver.jinojoseph.com:5000/jinojosephimage:v1.13         lifecycle:           postStart:             exec:               command:...
Post a Comment
Read more