Local Storage

Using local storage for Kubernetes workloads implies that the pod will be bound to the node where the local storage is available. Local storage is not replicated, so in case of a machine failure contents of the local storage will be lost.

hostPath mounts

The simplest way to use local storage is to use hostPath mounts. When using hostPath mounts, make sure the root directory of the mount is mounted into the kubelet container:

machine:
  kubelet:
    extraMounts:
      - destination: /var/mnt
        type: bind
        source: /var/mnt
        options:
          - bind
          - rshared
          - rw

Both EPHEMERAL partition and user disks can be used for hostPath mounts.

Local Path Provisioner

Local Path Provisioner can be used to dynamically provision local storage. Make sure to update its configuration to use a path under /var, e.g. /var/local-path-provisioner as the root path for the local storage. (In Talos Linux default local path provisioner path /opt/local-path-provisioner is read-only).

For example, Local Path Provisioner can be installed using kustomize with the following configuration:

# kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
- github.com/rancher/local-path-provisioner/deploy?ref=v0.0.26
patches:
- patch: |-
    kind: ConfigMap
    apiVersion: v1
    metadata:
      name: local-path-config
      namespace: local-path-storage
    data:
      config.json: |-
        {
                "nodePathMap":[
                {
                        "node":"DEFAULT_PATH_FOR_NON_LISTED_NODES",
                        "paths":["/var/local-path-provisioner"]
                }
                ]
        }    
- patch: |-
    apiVersion: storage.k8s.io/v1
    kind: StorageClass
    metadata:
      name: local-path
      annotations:
        storageclass.kubernetes.io/is-default-class: "true"    
- patch: |-
    apiVersion: v1
    kind: Namespace
    metadata:
      name: local-path-storage
      labels:
        pod-security.kubernetes.io/enforce: privileged    

Put kustomization.yaml into a new directory, and run kustomize build | kubectl apply -f - to install Local Path Provisioner to a Talos Linux cluster. There are three patches applied:

• change default /opt/local-path-provisioner path to /var/local-path-provisioner
• make local-path storage class the default storage class (optional)
• label the local-path-storage namespace as privileged to allow privileged pods to be scheduled there

As for the hostPath mounts (see above), this will require the kubelet to bind mount the node’s folder you chose (eg: /var/local-path-provisioner). Otherwise, you’ll have erratic behavior, especially when using the subPath statement in a volumeMount, which may lead to data loss and/or data never freed after PV deletion.

machine:
  kubelet:
    extraMounts:
      - destination: /var/local-path-provisioner
        type: bind
        source: /var/local-path-provisioner
        options:
          - bind
          - rshared
          - rw

To test the Local Path Provisioner, you can refer to the Usage section of the official guide.

You can check that directories for PVCs are created on the node’s filesystem with the talosctl ls /var/local-path-provisioner command.