Claudie storage solution

Concept

Running stateful workloads is a complex task, even more so when considering the multi-cloud environment. Claudie therefore needs to be able to accommodate stateful workloads, regardless of the underlying infrastructure providers.

Claudie orchestrates storage on the kubernetes cluster nodes by creating one "storage cluster" across multiple providers. This "storage cluster" has a series of zones, one for each cloud provider instance. Each zone then stores its own persistent volume data.

This concept is translated into longhorn implementation, where each zone is represented by a Storage Class which is backed up by the nodes defined under the same cloud provider instance. Furthermore, each node uses separate disk to the one, where OS is installed, to assure clear data separation. The size of the storage disk can be configured in storageDiskSize field of the nodepool specification.

Longhorn

A Claudie-created cluster comes with the longhorn deployment preinstalled and ready to be used. By default, only worker nodes are used to store data.

Longhorn installed in the cluster is set up in a way that it provides one default StorageClass called longhorn, which, if used, creates a volume that is then replicated across random nodes in the cluster.

Besides the default storage class, Claudie can also create custom storage classes, which force persistent volumes to be created on specific nodes based on the provider instance they have. In other words, you can use a specific provider instance to provision nodes for your storage needs, while using another provider instance for computing tasks.

Example

To follow along, have a look at the reference example input manifest file.

When Claudie applies this input manifest, the following storage classes are installed:

• longhorn - the default storage class, which stores data on random nodes
• longhorn-<provider instance>-zone - storage class, which stores data only on nodes of the specific provider instance (see the list of supported providers), i.e. longhorn-gcp-1-zone, longhorn-gcp-2-zone, longhorn-aws-1-zone, ...

For more information on how Longhorn works you can check out Longhorn's official documentation.