Configure a Pod to Use a Projected Volume for Storage

This page shows how to use a projected Volume to mount several existing volume sources into the same directory. Currently, secret, configMap, downwardAPI, and serviceAccountToken volumes can be projected.

Note: serviceAccountToken is not a volume type.

Before you begin

You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. It is recommended to run this tutorial on a cluster with at least two nodes that are not acting as control plane hosts. If you do not already have a cluster, you can create one by using minikube or you can use one of these Kubernetes playgrounds:

• Katacoda
• Play with Kubernetes

Configure a projected volume for a pod

In this exercise, you create username and password Secrets from local files. You then create a Pod that runs one container, using a projected Volume to mount the Secrets into the same shared directory.

Here is the configuration file for the Pod:

pods/storage/projected.yaml

apiVersion: v1
kind: Pod
metadata:
  name: test-projected-volume
spec:
  containers:
  - name: test-projected-volume
    image: busybox
    args:
    - sleep
    - "86400"
    volumeMounts:
    - name: all-in-one
      mountPath: "/projected-volume"
      readOnly: true
  volumes:
  - name: all-in-one
    projected:
      sources:
      - secret:
          name: user
      - secret:
          name: pass

1. Create the Secrets:

   # Create files containing the username and password:
   echo -n "admin" > ./username.txt
   echo -n "1f2d1e2e67df" > ./password.txt
   
   # Package these files into secrets:
   kubectl create secret generic user --from-file=./username.txt
   kubectl create secret generic pass --from-file=./password.txt
   

2. Create the Pod:

   kubectl apply -f https://k8s.io/examples/pods/storage/projected.yaml
   

3. Verify that the Pod's container is running, and then watch for changes to the Pod:

   kubectl get --watch pod test-projected-volume
   

   The output looks like this:

   NAME                    READY     STATUS    RESTARTS   AGE
   test-projected-volume   1/1       Running   0          14s
   

4. In another terminal, get a shell to the running container:

   kubectl exec -it test-projected-volume -- /bin/sh
   

5. In your shell, verify that the projected-volume directory contains your projected sources:

   ls /projected-volume/
   

Clean up

Delete the Pod and the Secrets:

kubectl delete pod test-projected-volume
kubectl delete secret user pass

What's next

• Learn more about projected volumes.
• Read the all-in-one volume design document.