Support Image Pull Secrets

If the images of fluid runtime is in private docker registry, it's necessary to set image pull secret. For related knowledge of image pull secret,
please refer to Pull an Image from a Private Registry

Fluid supports setting image pull secrets when you deploy fluid service using helm charts, you can set the image pull secrets to values.yaml like the following example

# fluid helm charts values.yaml 
# default imagePullSecrets value is empty
image:
  imagePullSecrets: []

# set values like this 
# suppose you have two image pull secret keys `test-1` and `test-2` in your cluster
image:
  imagePullSecrets: 
  - name: test-1
  - name: test-2

After setting values.yaml image pull secrets, when you have deployed the fluid service,
you can see that controller itself already uses image pull secrets

alluxio controller yaml intercepts information

apiVersion: apps/v1
kind: Deployment
metadata:
  name: alluxioruntime-controller
  namespace: fluid-system
spec:
  template:
    spec:
      containers:
      - image: fluidcloudnative/alluxioruntime-controller:
        name: manager
      dnsPolicy: ClusterFirst
      imagePullSecrets:
      - name: test-1
      - name: test-2

fluid also supports passing the image pull secrets through the controller to the runtime service that the controller pulls up

If you want to specify the image pull key for the runtime, you can do so by editing the environment variables in the deployment associated with the runtime controller that you have created.

Here is a brief YAML configuration example. When properly configured, the deployment will apply the image pull secret you specified.

- name: IMAGE_PULL_SECRETS
  value: test-1,test-2

In the above YAML file, IMAGE_PULL_SECRETS is the name of the environment variable, and test-1,test-2 are the image pull keys you wish to specify, separated by commas.

alluxio runtime master yaml intercepts information

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: demo-master
  namespace: test
spec:
  template:
    spec:
      containers:
      - image: fluidcloudnative/alluxio:release-2.8.1-SNAPSHOT-0433ade
        imagePullPolicy: IfNotPresent
        name: alluxio-master
      imagePullSecrets:
      - name: test1
      - name: test2

In conclusion, image pull secrets setting successfully