kubernetes - Deploying Openstack Magnum on bare metal

Question

When speaking about Openstack Magnum deployment of Kubernetes cluster (on bare metal nodes), is it somehow possible to leverage local disks on those nodes to act as persistent storage for containers?

In advance, thanks a lot.

Answer 1

Openstack Magnum uses Cinder to provision storage for kubernetes cluster. As you can read here:

In some use cases, data read/written by a container needs to persist so that it can be accessed later. To persist the data, a Cinder volume with a filesystem on it can be mounted on a host and be made available to the container, then be unmounted when the container exits.

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Kubernetes allows a previously created Cinder block to be mounted to a pod and this is done by specifying the block ID in the pod YAML file. When the pod is scheduled on a node, Kubernetes will interface with Cinder to request the volume to be mounted on this node, then Kubernetes will launch the Docker container with the proper options to make the filesystem on the Cinder volume accessible to the container in the pod. When the pod exits, Kubernetes will again send a request to Cinder to unmount the volume’s filesystem, making it available to be mounted on other nodes.

Its usage is described in this section of the documentation.

If setting up Cinder seems like too much overhead, you can use local volume type which allows to use local storage device such as a disk, partition or directory already mounted on a worker node's filesystem.