Mounting storage

git-csi-driver mounts a git repository as a volume, and per-node-csi-driver gives a pod a directory on the node it runs on. Kubernetes has neither kind of volume built in. Both are CSI drivers, so a pod mounts the volume like any other and sees a plain directory.

For example, Home Assistant can keep its configuration in a git repository on a writeable volume. Home Assistant edits its own files, and after 30 seconds with no writes the driver commits the changes and pushes them with a deploy key. If you delete the claim, a new claim on the same repository starts from the last push.

The operators

git-csi-driver mounts a git repository as a volume, under the driver name git.liken.sh. A read-only volume can be inline in a pod spec, or a claim, and its pull attribute is never, on-demand, or an interval. Pods on one node that mount the same repository share one fetch. A writeable volume commits what the pod writes and pushes it upstream, by the policy of a VolumeAttributesClass. Several applications can share one repository, with one directory each, and none of them reads the files of another.

per-node-csi-driver gives a pod a directory on the node it runs on, under the driver name per-node.liken.sh. A volume has one copy on each node, and the driver does not keep the copies in agreement. Use it for a cache that a pod on a new node fills again, or for a replicated store, where each pod holds a full copy and the pods keep the copies in agreement over the network. library-operator keeps its replicated catalog on this driver.

What they depend on

Each driver runs a node plugin as a privileged DaemonSet, which the kubelet reaches through its plugin directories. Each driver keeps its data on the partition that a Machine declares for pod storage, under /var/lib/liken/pod-storage. A machine with no such partition keeps that data in its RAM root, so it does not survive a reboot.

Neither driver uses the operators for claiming hardware.

Extension points

• Webhooks. git-csi-driver serves one Service that a forge posts to on each push, and the driver pulls the volume that the request names. GitHub, GitLab, Gitea, and Forgejo work. The Service speaks plain HTTP, and the Ingress that you write terminates TLS.
• The commit and push policy. A VolumeAttributesClass sets how long the driver waits before it commits, the longest delay before a push, the commit author, and the files to ignore. You can change the class of a live claim.
• A pull by hand. An annotation on the PersistentVolume asks the driver to pull now.
• Credentials. A Secret that you name on the volume holds the key or token for a private repository.