Скачать или смотреть Managing Container Storage with Kubernetes Volumes

Introduction
Kubernetes volumes offer a simple way to mount external storage to containers. This video shows how we can provide storage to some containers according to a provided specification.

Solution
Log in to the control plane server using the credentials provided:

ssh cloud_user@PUBLIC_IP_ADDRESS of the control plane
Create a Pod That Outputs Data to the Host Using a Volume
Create a Pod that will interact with the host file system:

vi maintenance-pod.yml
Enter in the first part of the basic YAML for a simple busybox Pod that outputs some data every five seconds to the host's disk:

apiVersion: v1
kind: Pod
metadata:
name: maintenance-pod
spec:
containers:
name: busybox
image: busybox
command: ['sh', '-c', 'while true; do echo Success! ** /output/output.txt; sleep 5; done']

** place 2 angle brackets there pointing rightwards

Under the basic YAML, begin creating volumes, which should be level with the containers spec:

volumes:
name: output-vol
hostPath:
path: /var/data
In the containers spec of the basic YAML, add a line for volume mounts:

volumeMounts:
name: output-vol
mountPath: /output
Check that the final maintenance-pod.yml file looks like this:

apiVersion: v1
kind: Pod
metadata:
name: maintenance-pod
spec:
containers:
name: busybox
image: busybox
command: ['sh', '-c', 'while true; do echo Success! ** /output/output.txt; sleep 5; done']

volumeMounts:
name: output-vol
mountPath: /output

volumes:
name: output-vol
hostPath:
path: /var/data
Save the file and exit by pressing the ESC key and using :wq.

** place 2 angle brackets there pointing rightwards

Finish creating the Pod:

kubectl create -f maintenance-pod.yml
Make sure the Pod is up and running:

kubectl get pods
Check that maintenance-pod is running, so it should be outputting data to the host system.

Log into the worker node server using the credentials provided:

ssh cloud_user@PUBLIC_IP_ADDRESS worker node
Look at the output to see whether the Pod setup was successful:

cat /var/data/output.txt
Create a Multi-Container Pod That Shares Data Between Containers Using a Volume
Return to the control plane server.

Create another YAML file for a shared-data multi-container Pod:

vi shared-data-pod.yml
Start with the basic Pod definition and add multiple containers, where the first container will write the output.txt file and the second container will read the output.txt file:

apiVersion: v1
kind: Pod
metadata:
name: shared-data-pod
spec:
containers:
name: busybox1
image: busybox
command: ['sh', '-c', 'while true; do echo Success! ** /output/output.txt; sleep 5; done']
name: busybox2
image: busybox
command: ['sh', '-c', 'while true; do cat /input/output.txt; sleep 5; done']

** place 2 angle brackets there pointing rightwards

Set up the volumes, again at the same level as containers with an emptyDir volume that only exists to share data between two containers in a simple way:

volumes:
name: shared-vol
emptyDir: {}

Mount that volume between the two containers by adding the following lines under command for the busybox1 container:

volumeMounts:
name: shared-vol
mountPath: /output

For the busybox2 container, add the following lines to mount the same volume under command to complete creating the shared file:

volumeMounts:
name: shared-vol
mountPath: /input

Make sure that the final shared-data-pod.yml file looks like this:

apiVersion: v1
kind: Pod
metadata:
name: shared-data-pod
spec:
containers:
name: busybox1
image: busybox
command: ['sh', '-c', 'while true; do echo Success! **/output/output.txt; sleep 5; done']
volumeMounts:
name: shared-vol
mountPath: /output
name: busybox2
image: busybox
command: ['sh', '-c', 'while true; do cat /input/output.txt; sleep 5; done']
volumeMounts:
name: shared-vol
mountPath: /input
volumes:
name: shared-vol
emptyDir: {}

Save the file and exit by pressing the ESC key and using :wq.

** place 2 angle brackets there pointing rightwards

Finish creating the multi-container Pod:

kubectl create -f shared-data-pod.yml
Make sure the Pod is up and running and check if both containers are running and ready:

kubectl get pods
To make sure the Pod is working, check the logs for shared-data-pod.yml and specify the second container that is reading the data and printing it to the console:

kubectl logs shared-data-pod -c busybox2
If you see the series of Success! messages, you have successfully created both containers, one of which is using a host path volume to write some data to the host disk and the other of which is using an emptyDir volume to share a volume between two containers in the same Pod.