Weka CSI Plugin

This page describes the Weka CSI Plugin prerequisites, capabilities, deployment, and usage.
Overview
The Container Storage Interface (CSI) is a standard for exposing arbitrary block and file storage systems to containerized workloads on Container Orchestration Systems (COs) like Kubernetes.
The Weka CSI Plugin provides the creation and configuration of persistent storage external to Kubernetes. CSI replaces plugins developed earlier in the Kubernetes evolution. It replaces the hostPath method to expose WekaFS mounts as Kubernetes volumes.
Interoperability
CSI protocol: 1.0-1.2
Kubernetes: 1.18
OS (of Kubernetes worker nodes): ubuntu 16.04, 18.04
WekaFS: 3.8 and up
Note: For additional Kubernetes/OS versions support contact the Weka support team
Prerequisites
Privileged mode must be allowed on the Kubernetes cluster
The following Kubernetes feature gates must be enabled: DevicePlugins, CSINodeInfo, CSIDriverRegistry, ExpandCSIVolumes (if not changed, they should be enabled by default)
A Weka cluster is installed and accessible from the Kubernetes worker nodes
The Weka client is installed on the Kubernetes worker nodes
It is recommended to use a Weka client which is part of the cluster rather than a stateless client​
If the Kubernetes nodes are part of the Weka cluster (converged mode on the Weka servers), make sure the Weka processes come up before kubelet
Filesystems are pre-configured on the Weka system
Capabilities
Supported capabilities
Static and dynamic volumes provisioning
Mounting a volume as a WekaFS filesystem directory
All volume access modes are supported: ReadWriteMany, ReadWriteOnce, and ReadOnlyMany
Volume expansion
Unsupported capabilities
Snapshots
Deployment
The Weka CSI Plugin deployment can be performed with a Helm chart or directly as a DaemonSet (as described below).
Download
Download the Weka CSI Plugin from GitHub to a master node in the Kubernetes cluster.
$ git clone https://github.com/weka/csi-wekafs.git
Installation
From the downloaded location in the Kubernetes master node, run the following command to deploy the Weka CSI Plugin as a DaemonsSet:
$ ./deploy/kubernetes-latest/deploy.sh
On successful deployment, you will see the following output:
creating wekafsplugin namespace
namespace/csi-wekafsplugin created
deploying wekafs components
   ./deploy/kubernetes-latest/wekafs/csi-wekafs-plugin.yaml
        using           image: quay.io/k8scsi/csi-node-driver-registrar:v1.3.0
        using           image: quay.io/weka.io/csi-wekafs:v0.0.2-25-g7d18b61
        using           image: quay.io/k8scsi/livenessprobe:v1.1.0
        using           image: quay.io/k8scsi/csi-provisioner:v1.6.0
        using           image: quay.io/k8scsi/csi-attacher:v3.0.0-rc1
        using           image: quay.io/k8scsi/csi-resizer:v0.5.0
namespace/csi-wekafsplugin configured
csidriver.storage.k8s.io/wekafs.csi.k8s.io created
serviceaccount/csi-wekafsplugin created
clusterrole.rbac.authorization.k8s.io/csi-wekafsplugin-cluster-role created
clusterrolebinding.rbac.authorization.k8s.io/csi-wekafsplugin-cluster-role-binding created
role.rbac.authorization.k8s.io/csi-wekafsplugin-role created
rolebinding.rbac.authorization.k8s.io/csi-wekafsplugin-role-binding created
daemonset.apps/csi-wekafsplugin created
12:04:54 deployment completed successfully
12:04:54 2 plugin pods are running:
csi-wekafsplugin-dvdh2   6/6     Running   0          3h1m
csi-wekafsplugin-xh182   6/6     Running   0          3h1m
The number of running pods should be the same as the number of Kubernetes worker nodes. This can be inspected by running:
$ kubectl get pods -n csi-wekafsplugin
NAME                     READY   STATUS    RESTARTS   AGE
csi-wekafsplugin-dvdh2   6/6     Running   0          3h2m
csi-wekafsplugin-xh182   6/6     Running   0          3h2m
Provision Usage
The Weka CSI Plugin supports both dynamic (persistent volume claim) and static (persistent volume) volume provisioning.
It is first required to define a storage class to use the Weka CSI Plugin.
Storage Class Example
csi-wekafs/examples/dynamic/storageclass-wekafs-dir.yaml
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: storageclass-wekafs-dir
provisioner: csi.weka.io
reclaimPolicy: Delete
volumeBindingMode: Immediate
allowVolumeExpansion: true
parameters:
  volumeType: dir/v1
  filesystemName: podsFilesystem
Storage Class Parameters
Parameter
Description
Limitation
filesystemName
The name of the Weka filesystem to create directories in as Kubernetes volumes
The filesystem should exist in the Weka cluster
Apply the StorageClass and check it has been created successfully:
# apply the storageclass .yaml file
$ kubectl apply -f storageclass-wekafs-dir.yaml
storageclass.storage.k8s.io/storageclass-wekafs-dir created
​
# check the storageclass resource has been created
$ kubectl get sc
NAME                           PROVISIONER         RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
storageclass-wekafs-dir        csi.weka.io         Delete          Immediate           true                   75s
It is possible to define multiple storage classes with different filesystems.
Dynamic Provisioning
Using a similar storage class to the above, it is possible to define a persistent volume claim (PVC) for the pods.
Persistent Volume Claim Example
csi-wekafs/examples/dynamic/pvc-wekafs-dir.yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-wekafs-dir
spec:
  accessModes:
    - ReadWriteMany
  storageClassName: storageclass-wekafs-dir
  volumeMode: Filesystem
  resources:
    requests:
      storage: 1Gi
Persistent Volume Claim Parameters
Parameter
Description
Limitation
spec.accessModes
The volume access mode
ReadWriteMany, ReadWriteOnce, or ReadOnlyMany
spec.storageClassName
The storage class to use to create the PVC
Must be an existing storage class
spec.resources.requests.storage
A desired capacity for the volume
The capacity quota is not enforced but is stored on the filesystem directory extended attributed for future use
Apply the PersistentVolumeClaim and check it has been created successfully:
# apply the pvc .yaml file
$ kubectl apply -f pvc-wekafs-dir.yaml
persistentvolumeclaim/pvc-wekafs-dir created
​
# check the pvc resource has been created
$ kubectl get pvc
NAME                  STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS                   AGE
pvc-wekafs-dir        Bound    pvc-d00ba0fe-04a0-4916-8fea-ddbbc8f43380   1Gi        RWX            storageclass-wekafs-dir        2m10s
Note: The directory will be created inside the filesystem under csi-volumes directory, starting with the volume name.
Static Provisioning
The Kubernetes admin can prepare some persistent volumes in advance to be used by pods, they should be an existing directory, and can contain pre-populated data to be used by the PODs.
It can be a directory previously provisioned by the CSI or a pre-existing directory in WekaFS. To expose an existing directory in WekaFS via CSI, define a persistent volume, and link a persistent volume claim to this persistent volume.
Persistent Volume Example
csi-wekafs/examples/static/pv-wekafs-dir-static.yaml
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-wekafs-dir-static
spec:
  storageClassName: storageclass-wekafs-dir
  accessModes:
    - ReadWriteMany
  persistentVolumeReclaimPolicy: Retain
  volumeMode: Filesystem
  capacity:
    storage: 1Gi
  csi:
    driver: csi.weka.io
    # volumeHandle must be formatted as following:
    # dir/v1/<FILE_SYSTEM_NAME>/<INNER_PATH_IN_FILESYSTEM>
    # The path must exist, otherwise publish request will fail
    volumeHandle: dir/v1/podsFilesystem/my-dir
Persistent Volume Parameters
Parameter
Description
Limitation
spec.accessModes
The volume access mode
ReadWriteMany, ReadWriteOnce, or ReadOnlyMany
spec.storageClassName
The storage class to use to create the PV
Must be an existing storage class
spec.capacity.storage
A desired capacity for the volume
The capacity quota is not enforced but is stored on the filesystem directory extended attributed for future use
spec.csi.volumeHandle
A string specifying a previously created path
A string containing the volumeType (dir/v1) filesystem name, and the directory path. E.g. dir/v1/podsFilesystem/my-dir
Must be an existing filesystem and path
Apply the PersistentVolume and check it has been created successfully:
# apply the pv .yaml file
$ kubectl apply -f pv-wekafs-dir-static.yaml
persistentvolume/pv-wekafs-dir-static created
​
# check the pv resource has been created
$ kubectl get pv
NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM                         STORAGECLASS                   REASON   AGE
pv-wekafs-dir-static                       1Gi        RWX            Retain           Available                                 storageclass-wekafs-dir                 3m33s
Now, bind a PVC to this specific PV, use the volumeName parameter under the PVC spec and provide it with the specific PV name.
Persistent Volume Claim for Static Provisioning Example
csi-wekafs/examples/static/pvc-wekafs-dir-static.yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-wekafs-dir-static
spec:
  accessModes:
    - ReadWriteMany
  storageClassName: storageclass-wekafs-dir
  volumeName: pv-wekafs-dir-static
  volumeMode: Filesystem
  resources:
    requests:
      storage: 1Gi
Persistent Volume Claim for Static Provisioning Example
Parameter
Description
Limitation
spec.accessModes
The volume access mode
ReadWriteMany, ReadWriteOnce, or ReadOnlyMany
spec.storageClassName
The storage class to use to create the PVC
Must be the same storage class as the PV requested to bind in spec.volumeName
spec.resources.requests.storage
A desired capacity for the volume
The capacity quota is not enforced but is stored on the filesystem directory extended attributed for future use
spec.volumeName
A name of a pre-configured persistent volume
Must be an existing PV name
Apply the PersistentVolumeClaim and check it has been created successfully:
# apply the pvc .yaml file
$ kubectl apply -f pvc-wekafs-dir-static.yaml
persistentvolumeclaim/pvc-wekafs-dir-static created
​
# check the pvc resource has been created
$ kubectl get pvc
NAME                    STATUS   VOLUME                CAPACITY   ACCESS MODES   STORAGECLASS                   AGE
pvc-wekafs-dir-static   Bound    pv-wekafs-dir-static  1Gi        RWX            storageclass-wekafs-dir        3m41s
The PV will change the status to Bound and state the relevant claim it is bounded to:
# check the pv resource has been created
$ kubectl get pv
NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM                           STORAGECLASS                   REASON   AGE
pv-wekafs-dir-static                       1Gi        RWX            Retain           Bound       default/pvc-wekafs-dir-static   storageclass-wekafs-dir                 6m30s
Launching an Application using Weka as the POD's Storage
Now that we have a storage class and a PVC in place, we can configure the Kubernetes pods to provision volumes via the Weka system.
We'll take an example application that echos the current timestamp every 10 seconds, and provide it with the previously created pvc-wekafs-dir PVC.
Note that multiple pods can share a volume produced by the same PVC as long as the accessModes parameter is set to ReadWriteMany.
csi-wekafs/examples/dynamic/csi-app-on-dir.yaml
kind: Pod
apiVersion: v1
metadata:
  name: my-csi-app
spec:
  containers:
    - name: my-frontend
      image: busybox
      volumeMounts:
      - mountPath: "/data"
        name: my-csi-volume
      command: ["/bin/sh"]
      args: ["-c", "while true; do echo `date` >> /data/temp.txt; sleep 10;done"]
  volumes:
    - name: my-csi-volume
      persistentVolumeClaim:
        claimName: pvc-wekafs-dir # defined in pvc-wekafs-dir.yaml
Now we will apply that pod:
$ kubectl apply -f csi-app-on-dir.yaml
pod/my-csi-app created
Kubernetes will allocate a persistent volume and attach it to the pod, it will use a directory within the WekaFS filesystem as defined in the storage class mentioned in the persistent volume claim. The pod will be in Running status, and the temp.txt file will get updated with occasional date information.
$ kubectl get pod my-csi-app
NAME                      READY   STATUS              RESTARTS   AGE
my-csi-app                1/1     Running             0          85s
​
# if we go to a wekafs mount of this filesystem we can see a directory has been created
$ ls -l /mnt/weka/podsFilesystem/csi-volumes
drwxr-x--- 1 root root 0 Jul 19 12:18 pvc-d00ba0fe-04a0-4916-8fea-ddbbc8f43380-a1659c8a7ded3c3c05d6facffd69cbf79b95604c
​
# inside that directory, the temp.txt file from the running pod can be found
 $ cat /mnt/weka/podsFilesystem/csi-volumes/pvc-d00ba0fe-04a0-4916-8fea-ddbbc8f43380-a1659c8a7ded3c3c05d6facffd69cbf79b95604c/temp.txt
Sun Jul 19 12:50:25 IDT 2020
Sun Jul 19 12:50:35 IDT 2020
Sun Jul 19 12:50:45 IDT 2020
Troubleshooting
Useful Commands
Here are some useful basic commands to check the status and debug the service:
# get all resources
kubectl get all --all-namespaces
​
# get all pods
kubectl get pods --all-namespaces -o wide
​
# get all k8s nodes
kubectl get nodes
​
# get storage classes
$ kubectl get sc
​
# get persistent volume claims 
$ kubectl get pvc
​
# get persistent volumes
$ kubectl get pv
​
# kubectl describe pod/<pod-name> -n <namespace> 
kubectl describe pod/csi-wekafsplugin-dvdh2 -n csi-wekafsplugin
​
# get logs from a pod
kubectl logs <pod name> <container name>
​
# get logs from the weka csi plugin
# container (-c) can be one of: [node-driver-registrar wekafs liveness-probe csi-provisioner csi-attacher csi-resizer]
kubectl logs pods/csi-wekafsplugin-<ID> --namespace csi-wekafsplugin -c wekafs
Known Issues
Mixed Hugepages Size Issue
Due to a Kubernetes v1.18 issue with allocating mixed hugepages sizes (https://github.com/kubernetes/kubernetes/pull/80831) is required that the Weka system will not try to allocate mixed sizes of hugepages on the Kubernetes nodes.
To workaround the Kubernetes issue (required only if the default memory for the client has been increased):
If the Weka client is installed on the K8s nodes via a manual stateless client mount, set the reserve_1g_hugepages mount option to false in the mount command.
If this is a Weka server or a Weka client, which is part of the Weka cluster, contact the Weka customer support team.
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External Monitoring
Last updated 6 months ago
Parameter	Description	Limitation
`filesystemName`	The name of the Weka filesystem to create directories in as Kubernetes volumes	The filesystem should exist in the Weka cluster