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Demo - Access Dataset cache across Namespace (CSI mechanism)

This demo is used to show how to use a Dataset cache across Namespace.

  • In Namespace ns-a, create Dataset demo and AlluxioRuntime demo
  • In Namespace ns-b create Dataset demo-ref and ThinRuntime demo-ref. The mountPoint of demo-ref is dataset://ns-a/demo

Prerequests

Before running this demo, please refer to the installation documentation to complete the installation and check that the components of Fluid are working properly:

$ kubectl get pod -n fluid-system
alluxioruntime-controller-5b64fdbbb-84pc6   1/1     Running   0          8h
csi-nodeplugin-fluid-fwgjh                  2/2     Running   0          8h
csi-nodeplugin-fluid-ll8bq                  2/2     Running   0          8h
dataset-controller-5b7848dbbb-n44dj         1/1     Running   0          8h
thinruntime-controller-7dcbf5f45-xsf4p          1/1     Running   0          8h

Where thinruntime-controller is used to support Dataset sharing across Namespace and alluxioruntime-controller is the actual cache.

Share Dataset cache across Namespace through CSI mechanism

1. Create Dataset and Cache Runtime

In default Namespace，create phy Dataset and AlluxioRuntime.

$ cat<<EOF >ds.yaml
apiVersion: data.fluid.io/v1alpha1
kind: Dataset
metadata:
  name: phy
spec:
  mounts:
    - mountPoint: https://mirrors.bit.edu.cn/apache/spark/
      name: spark
---
apiVersion: data.fluid.io/v1alpha1
kind: AlluxioRuntime
metadata:
  name: phy
spec:
  replicas: 1
  tieredstore:
    levels:
      - mediumtype: MEM
        path: /dev/shm
        quota: 1Gi
        high: "0.95"
        low: "0.7"
EOF

$ kubectl create -f ds.yaml

2. Create referenced Dataset and Runtime

In Namespace ref, create:

  • the referenced dataset refdemo, whose mountPoint format is dataset://${origin-dataset-namespace}/${origin-dataset-name}.

Note:

  1. Currently, the referenced Dataset only supports single mount and its form must be dataset:// (i.e. the creation of a dataset fails when dataset:// and other forms both appear), and other fields in the Spec are invalid.
  2. The fields in Spec of the referenced Runtime corresponding to the Dataset are invalid.
$ kubectl create ns ref

$ cat<<EOF >ds-ref.yaml
apiVersion: data.fluid.io/v1alpha1
kind: Dataset
metadata:
  name: refdemo
spec:
  mounts:
    - mountPoint: dataset://default/phy
      name: fusedemo
      path: "/"
EOF

$ kubectl create -f ds-ref.yaml -n ref

Create Pod and Check the data

In default Namespace, create a Pod

$ cat<<EOF >app.yaml
apiVersion: v1
kind: Pod
metadata:
  name: nginx
spec:
  containers:
    - name: nginx
      image: nginx
      volumeMounts:
        - mountPath: /data_spark
          name: spark-vol
  volumes:
    - name: spark-vol
      persistentVolumeClaim:
        claimName: phy
EOF

$ kubectl create -f app.yaml

In Namespace ref, create a Pod：

$ cat<<EOF >app-ref.yaml
apiVersion: v1
kind: Pod
metadata:
  name: nginx
spec:
  containers:
    - name: nginx
      image: nginx
      volumeMounts:
        - mountPath: /data_spark
          name: spark-vol
  volumes:
    - name: spark-vol
      persistentVolumeClaim:
        claimName: refdemo
EOF

$ kubectl create -f app-ref.yaml -n ref

In Namespace ref, check the status of the app nginx pod.

$ kubectl get pods -n ref -o wide
NAME         READY   STATUS    RESTARTS   AGE   IP              NODE      NOMINATED NODE   READINESS GATES
nginx        1/1     Running   0          11m   10.233.109.66   work02    <none>           <none>

In default Namespace, check the Pod information.

  • Only one AlluxioRuntime cluster exists, i.e. there is only one cache.
  • An extra phy-fuse-nmf88 because the nginx pod under the ref namespace is scheduled on node133.
$ kubectl get pods -o wide
NAME             READY   STATUS    RESTARTS   AGE     IP              NODE      NOMINATED NODE   READINESS GATES
nginx            1/1     Running   0          5m9s    10.233.109.65   work02    <none>           <none>
phy-fuse-59tw2   1/1     Running   0          10s     172.16.2.133    node133   <none>           <none>
phy-fuse-nmf88   1/1     Running   0          5m9s    172.16.1.10     work02    <none>           <none>
phy-master-0     2/2     Running   0          7m2s    172.16.1.10     work02    <none>           <none>
phy-worker-0     2/2     Running   0          6m29s   172.16.1.10     work02    <none>           <none>