Kubernetes - Mounting a Host Path On To Pod

We already know kubernetes provides us with multiple ways of saving data on the disk. We have seen volume types using emptyDir and memory. The other and most used volume type is the Hostpath. In this article we will see how we can use a host path on disk to mount on to the pod and save data from the pod to the host machine.

The Host path details are defined in the volumes and attached to the pod using the VolumeMounts. Check the below example,

[jagadishmanchala@Jagadish-theOne:k8s] cat hostpath-volume.yml 

apiVersion: v1

kind: Pod

metadata:

  name: myapp

spec:

  containers:

  - name: my-app

    image: nginx

    ports:

    - containerPort: 8080

    volumeMounts:

    - name: my-volume

      mountPath: /app

  volumes:

  - name: my-volume

    hostPath:

      path: /Volumes/Working/k8s/test

In the above code, we are using the hostpath /Volumes/Working/k8s/test directory on the host machine to be mounted to the container on /app location. The name of the mount is my-volume

Run the code to see if the pod is running as below,

[jagadishmanchala@Jagadish-theOne:k8s] kubectl get pods

NAME            READY   STATUS    RESTARTS   AGE

myapp           1/1     Running   0          30s

Login to the pod and create few files for testing as below,

[jagadishmanchala@Jagadish-theOne:k8s] kubectl exec myapp -c my-app -it -- bash

root@myapp:/# df -hT

Filesystem     Type           Size  Used Avail Use% Mounted on

overlay        overlay         59G  4.5G   51G   8% /

tmpfs          tmpfs           64M     0   64M   0% /dev

tmpfs          tmpfs          987M     0  987M   0% /sys/fs/cgroup

grpcfuse       fuse.grpcfuse   47G   33G   14G  71% /app

/dev/vda1      ext4            59G  4.5G   51G   8% /etc/hosts

shm            tmpfs           64M     0   64M   0% /dev/shm

tmpfs          tmpfs          987M   12K  987M   1% /run/secrets/kubernetes.io/serviceaccount

tmpfs          tmpfs          987M     0  987M   0% /sys/firmware

root@myapp:/# cd /app/

root@myapp:/app# touch hai hello

root@myapp:/app# exit

exit

Now check on the host path to confirm as below,

[jagadishmanchala@Jagadish-theOne:k8s] ll test/

total 0

-rw-r--r--  1 jagadishmanchala  staff  0 Dec 28 12:30 hai

-rw-r--r--  1 jagadishmanchala  staff  0 Dec 28 12:30 hello

Hope this helps in understanding the hostpath Volume.