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rancher-charts/charts/longhorn/103.2.0+up1.5.1/README.md

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Longhorn Chart

Important: Please install the Longhorn chart in the longhorn-system namespace only.

Warning: Longhorn doesn't support downgrading from a higher version to a lower version.

Source Code

Longhorn is 100% open source software. Project source code is spread across a number of repos:

  1. Longhorn Engine -- Core controller/replica logic https://github.com/longhorn/longhorn-engine
  2. Longhorn Instance Manager -- Controller/replica instance lifecycle management https://github.com/longhorn/longhorn-instance-manager
  3. Longhorn Share Manager -- NFS provisioner that exposes Longhorn volumes as ReadWriteMany volumes. https://github.com/longhorn/longhorn-share-manager
  4. Backing Image Manager -- Backing image file lifecycle management. https://github.com/longhorn/backing-image-manager
  5. Longhorn Manager -- Longhorn orchestration, includes CSI driver for Kubernetes https://github.com/longhorn/longhorn-manager
  6. Longhorn UI -- Dashboard https://github.com/longhorn/longhorn-ui

Prerequisites

  1. A container runtime compatible with Kubernetes (Docker v1.13+, containerd v1.3.7+, etc.)
  2. Kubernetes >= v1.21
  3. Make sure bash, curl, findmnt, grep, awk and blkid has been installed in all nodes of the Kubernetes cluster.
  4. Make sure open-iscsi has been installed, and the iscsid daemon is running on all nodes of the Kubernetes cluster. For GKE, recommended Ubuntu as guest OS image since it contains open-iscsi already.

Upgrading to Kubernetes v1.25+

Starting in Kubernetes v1.25, Pod Security Policies have been removed from the Kubernetes API.

As a result, before upgrading to Kubernetes v1.25 (or on a fresh install in a Kubernetes v1.25+ cluster), users are expected to perform an in-place upgrade of this chart with enablePSP set to false if it has been previously set to true.

Note: If you upgrade your cluster to Kubernetes v1.25+ before removing PSPs via a helm upgrade (even if you manually clean up resources), it will leave the Helm release in a broken state within the cluster such that further Helm operations will not work (helm uninstall, helm upgrade, etc.).

If your charts get stuck in this state, you may have to clean up your Helm release secrets. Upon setting enablePSP to false, the chart will remove any PSP resources deployed on its behalf from the cluster. This is the default setting for this chart.

As a replacement for PSPs, Pod Security Admission should be used. Please consult the Longhorn docs for more details on how to configure your chart release namespaces to work with the new Pod Security Admission and apply Pod Security Standards.

Uninstallation

To prevent Longhorn from being accidentally uninstalled (which leads to data lost), we introduce a new setting, deleting-confirmation-flag. If this flag is false, the Longhorn uninstallation job will fail. Set this flag to true to allow Longhorn uninstallation. You can set this flag using setting page in Longhorn UI or kubectl -n longhorn-system patch -p '{"value": "true"}' --type=merge lhs deleting-confirmation-flag

To prevent damage to the Kubernetes cluster, we recommend deleting all Kubernetes workloads using Longhorn volumes (PersistentVolume, PersistentVolumeClaim, StorageClass, Deployment, StatefulSet, DaemonSet, etc).

From Rancher Cluster Explorer UI, navigate to Apps page, delete app longhorn then app longhorn-crd in Installed Apps tab.

Please see link for more information.