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 - 1.2

  • WekaFS: 3.8 and up

  • AppArmor and SELinux are not supported yet

Note: Quota enforcement on persistent volumes requires WekaFS version 3.13 and up

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

  • 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

  • Quota enforcement on persistent volumes

Note: Quota enforcement on persistent volumes requires WekaFS version 3.13 and up. For additional information about enforcing quota on existing persistent volumes, refer to the Upgrading Legacy Persistent Volumes for Capacity Enforcement section

Unsupported capabilities

  • Snapshots

Deployment

The Weka CSI Plugin deployment can be performed with a Helm chart from the official Weka ArtifactHub repository.

Installation

On your workstation (assuming connectivity to Kubernetes cluster), add the csi-wekafs repository:

Install the plugin by issuing the following command:

On successful installation the following output will be shown:

Upgrade

Clean Up a Direct Deployment of CSI Driver

Note: Upgrading a plugin deployed directly (via deploy.sh script) is not supported. This section describes the procedure to clean up the existing CSI plugin components. After cleanup, proceed to the Installation section.

If the previous version was installed using Helm, you can safely skip this section.

Download the csi-wekafs git repository

Assuming connectivity to Kubernetes cluster is valid, run the following script to remove the CSI driver components:

Upgrade an Existing Helm Release

Note: If you plan to upgrade existing Weka CSI plugin deployment and enable directory quota enforcement for already existing volumes, please refer to the Binding Legacy Volumes to API section.

If not yet configured, add the Helm repository as defined in the Installation section.

Execute the following command:

A successful upgrade will produce the following output:

CSI Plugin and WekaFS Cluster Software Upgrade

The CSI Plugin fetches the WekaFS cluster capabilities during the first login to the API endpoint and caches it throughout the login refresh token validity period, to improve the efficiency and performance of the plugin.

However, the WekaFS cluster upgrade might come unnoticed if performed during this time window, continuing to provision new volumes in legacy mode.

In order to expedite the update of the Weka cluster capabilities, it is recommended to delete all the CSI Plugin pods, to invalidate the cache. The pods will then be restarted.

Storage Class Configuration

The Weka CSI Plugin supports both dynamic (persistent volume claim) and static (persistent volume) volume provisioning. For provisioning either type of a persistent volume, a Storage Class must exist in Kubernetes deployment that matches the Weka cluster configuration.

In the Legacy communication model, the Weka CSI Plugin does not communicate with the Weka cluster via API and solely relies on in-band communication via the data plane. This configuration does not provide extended configuration abilities.

In the API-Based communication model, the Weka CSI Plugin communicates with the Weka cluster using REST API, leveraging this integration to provide extended abilities, such as strict enforcement of volume capacity usage via integration with WekaFS directory quota functionality.

Note: Only the API-Based communication model will be maintained and enhanced with new capabilities. If you are running the legacy CSI plugin, it is advisable to replace it with the API-Based one.

Legacy Communication Model

This model assumes no API connectivity to the Weka cluster. As a result, the functionality provided by the Weka CSI plugin is limited.

Note: This section refers to the configuration of the CSI plugin prior to version v0.7.0

Although this configuration is supported in version 0.7.0 and up, the user is encouraged to upgrade any existing deployment of the Weka CSI plugin to the API-based model

It is first required to define a storage class to use the Weka CSI Plugin.

Storage Class Example

Storage Class Parameters

Parameter

Description

Limitations

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:

It is possible to define multiple storage classes with different filesystems.

API-Based Communication Model

In the API-based model, the API endpoint addresses and authentication credentials must be provided to the Weka CSI plugin in order to establish a REST API connection with the Weka cluster and perform configuration tasks on it.

The information is stored securely in Kubernetes secret, which is, in turn, referred to by the Storage Class.

Note: This section refers to the configuration of CSI plugin version v0.7.0 and up.

Note: Directory quota integration requires WekaFS software version v3.13.0 and up.

Note: Authenticated mounts for filesystems set with auth-required=true, and filesystems in the non-root organization, require WekaFS software version v3.14.0 and up.

Note: It is recommended to deploy the CSI plugin in API-Based communication model even if the Weka cluster is below version v3.13.0

Volumes provisioned using the API-Based model on older Weka clusters, do not support capacity enforcement, and are still considered "Legacy". However, they can be easily upgraded to capacity enforcement capabilities after the Weka cluster upgrade.

Secret Data Example

Secret Data Parameters

Note: Make sure that all data is base64-encoded when creating a secret.

Key

Description

Notes

username

The user name for API access to the Weka cluster, in base64 encoding.

Must have at least read-write permissions in the organization. It is recommended to create a separate user with admin privileges for the CSI plugin

password

The user password for API access to the Weka cluster, in base64 encoding.

organization

The Weka organization name for the user, in base64 encoding (use Root if you only have one organization).

Multiple secrets may be used to provide access to multiple organizations, which in turn will be specified in different storage classes

scheme

The URL scheme used to commnicate with the Weka cluster API.

http or https can be used. The user must ensure that the Weka cluster was configured to use the same connection scheme.

endpoints

Comma-separated list of endpoints consisting of IP address and port, e.g.

172.31.15.113:14000,172.31.12.91:14000

The management IP addresses of at least 2 backend hosts should be provided for redundancy.

Apply the Secret and check it has been created successfully:

Note: To provision CSI volumes on filesystem residing in non-root organizations, or filesystems set with auth-required=true, CSI plugin of version 0.7.4 or higher is required, as well as Weka software of version 3.14 or higher

Storage Class Example

Storage Class Parameters

Parameter

Description

filesystemName

The name of the Weka filesystem to create directories in as Kubernetes volumes.

  • The filesystem must exist on the Weka cluster

  • The filesystem may not be defined as "authenticated"

capacityEnforcement

Can be HARD or SOFT

  • HARD: strictly enforce quota and deny any write operation to the persistent volume consumer until space is freed up

  • SOFT: do not strictly enforce the quota, but create an alert on the Weka cluster

ownerUid

Effective User ID of the owner user for the provisioned CSI volume. Might be required for application deployments running under non-root accounts. Defaults to 0

ownerGid

Effective Group ID of the owner user for the provisioned CSI volume. Might be required for application deployments running under non-root accounts. Defaults to 0

permissions

Unix permissions for the provisioned volume root directory, in octal format. Must be set in quotes. Defaults to "0775"

csi.storage.k8s.io/provisioner-secret-name

Name of the K8s secret, e.g. csi-wekafs-api-secret

It is recommended to use an anchor definition in order to avoid mistakes since the same value has to be entered in additional fields below, according to the CSI spec definitions. Refer to the example above for exact formatting.

csi.storage.k8s.io/provisioner-secret-namespace

The namespace the secret is located in.

The secret does not have to be located in the same namespace as the CSI plugin is installed.

It is recommended using an anchor definition in order to avoid mistakes since the same value has to be entered in additional fields below, accordings to the CSI spec definitions. Refer to the example above for exact formatting.

Apply the StorageClass and check it has been created successfully:

  • It is possible to define multiple storage classes with different filesystems.

  • The same secret may be reused for multiple storage classes, as long as credentials are valid to access the filesystem

  • Several secrets may be used, e.g., for different organizations on the same Weka cluster, or for different Weka clusters spanning across the same Kubernetes cluster

Note: Multiple weka cluster connections from the same Kubernetes node are not supported in the current release of Weka software.

However, different Kubernetes nodes within the same cluster (e.g., in different regions or availability zones) can be connected to different Weka clusters. In such a case, provided that the Weka CSI plugin can access the Weka cluster REST API, a single CSI plugin instance can orchestrate persistent volume provisioning on multiple clusters.

Provision Usage

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

Persistent Volume Claim Parameters

Parameter

Description

Limitations

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:

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

Persistent Volume Parameters

Parameter

Description

Limitations

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:

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

Persistent Volume Claim for Static Provisioning Example

Parameter

Description

Limitations

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:

The PV will change the status to Bound and state the relevant claim it is bounded to:

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.

Now we will apply that pod:

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.

Upgrading Legacy Persistent Volumes for Capacity Enforcement

Binding Legacy Volumes to API

Capacity enforcement and integration with WekaFS directory quotas require several prerequisites:

  1. Weka CSI plugin version 0.7.0 and up

  2. WekaFS software version v3.13.0 and up

  3. Weka CSI plugin ability to communicate with WekaFS using REST API, and correlate between a certain persistent volume and the WekaFS cluster serving this volume.

In the API-Based communication model, Kubernetes StorageClass refers to a secret that describes all the required parameters for API calls to the Weka cluster. However, this is not the situation in the legacy communication model, where the storage class doesn't specify the API credentials.

Kubernetes does not allow modification of StorageClass parameters, hence every volume created with the legacy-model storage class will never report its credentials.

Weka CSI Plugin 0.7.0 provides a special configuration mode in which legacy volumes can be bound to a single secret, in turn referring to a single WekaFS cluster API connection parameters. In this configuration mode, every request to serve (create, delete, expand...) a legacy Persistent Volume (or Persistent Volume Claim) that originates from a Legacy Storage Class (without reference to an API secret) will be communicated to that cluster.

Note: Volumes provisioned by the CSI Plugin of version 0.7.0 in the API-Based communication model, but on older versions of the Weka cluster (below version 3.13.0), are still provisioned in legacy mode.

However, since the storage class already contains the secret reference, specifying the legacyVolumeSecretName parameter is unnecessary, and you can safely skip to the next chapter.

This configuration can be applied following these two steps:

  1. Create a Kubernetes secret that describes the API communication parameters for legacy volumes.

    1. The format of the secret is identical to the secret defined in the API-Based Communication Model section

    2. This secret must be located in the same Kubernetes namespace of the Weka CSI Plugin

  2. Set the legacyVolumeSecretName parameter to match the name of secret above during plugin upgrade or installation

    This can be done by directly modifying the values.yaml or by explicitly setting the parameter during the Helm upgrade:

Note: The Kubernetes secret must be created before executing the helm upgrade. Otherwise, the CSI Plugin components will remain in a Pending state after the upgrade.

Upgrading Legacy Volumes

Once the volume to API binding configuration described in the previous section is performed, the volumes may be migrated by binding a new WekaFS directory quota object to an existing persistent volume.

Weka provides a migration script that automates the process.

Note: This procedure must be performed only once, and can be performed from any Linux host that is connected to the same WekaFS cluster. Additional runs of the script will migrate only those volumes that were created in legacy mode after the migration process. It is safe to execute the migration script multiple times, although usually this should not be required.

Note: The migration process might take significant time to complete and depends on a number of persistent volumes and their actual capacity. The migration process is performed transparently and does not require downtime.

Check out the csi-wekafs repository from any host that is connected to WekaFS cluster:

Execute the migration script by issuing the following command, where <filesystem_name> states the filesystem name which the CSI volumes are located on, and optional <csi_volumes_dir> parameter states the directory inside the filesystem where CSI volumes are stored (only if the directory differs from default values)

Note: On a stateless client, the --endpoint-address must be specified in order to successfully mount a filesystem, while on a host which is part of the Weka cluster (either client or backend) this is not necessary.

Note: If multiple filesystems are used, the script must be executed for each filesystem

For example:

Note: The migration script requires several dependencies, which must be installed in advance: jq, xattr, getfattr, setfattr

Refer to the specific OS package management documentation to install the necessary packages.

Troubleshooting

Useful Commands

Here are some useful basic commands to check the status and debug the service:

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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