How to place SQLite database outside of NFS Persistent Volume

Question

I have a multi-node (2) Kubernetes cluster running on bare metal. I understand that 1. hostPath is bad for production and 2. hostPath Persistent Volumes are not supported for multi-node setups. Is there a way that I can safely run apps that are backed by a SQLite database? Over NFS the database locks a lot and really hurts the performance of the apps.

I would probably place the SQLite databases for each app on the hostPath volume and everything would run smoothly again. But I was wondering if there are some workarounds to achieve this, even if I have to restrict apps to a specific node.

Answer 1

It seems you should use Local Persistent Volumes GA.

As per documentation:

A local volume represents a mounted local storage device such as a disk, partition or directory.

Compared to hostPath volumes, local volumes can be used in a durable and portable manner without manually scheduling Pods to nodes, as the system is aware of the volume’s node constraints by looking at the node affinity on the PersistentVolume.

However:

At GA, Local Persistent Volumes do not support dynamic volume provisioning.

More information you can find here, and here.

As one example:

apiVersion: v1
kind: PersistentVolume
metadata:
  name: example-pv
spec:
  capacity:
    storage: 100Gi
  # volumeMode field requires BlockVolume Alpha feature gate to be enabled.
  volumeMode: Filesystem
  accessModes:
  - ReadWriteOnce
  persistentVolumeReclaimPolicy: Delete
  storageClassName: local-storage
  local:
    path: /mnt/disks/ssd1
  nodeAffinity:
    required:
      nodeSelectorTerms:
      - matchExpressions:
        - key: kubernetes.io/hostname
          operator: In
          values:
          - example-node

With Local Persistent Volumes, the Kubernetes scheduler ensures that a pod using a Local Persistent Volume is always scheduled to the same node