Deploy - Important Notes - 《Longhorn v1.4.2 Documentation》

Notes

Important Notes

This page lists important notes for Longhorn v1.4.2. Please see here for the full release note.

Notes

Supported Kubernetes Versions

Please ensure your Kubernetes cluster is at least v1.21 before upgrading to Longhorn v1.4.2 because the supported Kubernetes version has been updated in v1.4.2.

Recurring Jobs

After the upgrade, the recurring job settings of volumes will be migrated to new recurring job resources, and the RecurringJobs field in the volume spec will be deprecated. [doc]

The behavior of the recurring job types Snapshot and Backup will attempt to delete old snapshots first if they exceed the retained count before creating a new snapshot. Additionally, two new recurring job types have been introduced, Snapshot Force Create and Backup Force Create. They retain the original behavior of taking a snapshot or backup first before deleting outdated snapshots.

Backup Migration Time

When upgrading from a Longhorn version >= 1.2.0 and <= v1.2.3 to v1.4.2, if your cluster has many backups, you may expect to have a long upgrade time (with 22000 backups, it could take a few hours). Helm upgrade may timeout and you may need to re-run the upgrade command or set a longer timeout. This is a known issue.

Longhorn 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. See more in the uninstall section.

Pod Security Policies Disabled & Pod Security Admission Introduction

Longhorn pods require privileged access to manage nodes’ storage. In Longhorn v1.3.x or older, Longhorn was shipping some Pod Security Policies by default, (e.g., link). However, Pod Security Policy has been deprecated since Kubernetes v1.21 and removed since Kubernetes v1.25, link. Therefore, we stopped shipping the Pod Security Policies by default. For Kubernetes < v1.25, if your cluster still enables Pod Security Policy admission controller, please do:
- Helm installation method: set the helm value enablePSP to true to install longhorn-psp PodSecurityPolicy resource which allows privileged Longhorn pods to start.
- Kubectl installation method: need to apply the podsecuritypolicy.yaml manifest in addition to applying the longhorn.yaml manifests.
- Rancher UI installation method: set Other Settings > Pod Security Policy to true to install longhorn-psp PodSecurityPolicy resource which allows privileged Longhorn pods to start.
As a replacement for Pod Security Policy, Kubernetes provides a new mechanism, Pod Security Admission. If you enable the Pod Security Admission controller and change the default behavior to block privileged pods, you must add the correct labels to the namespace where Longhorn pods run to allow Longhorn pods to start successfully (because Longhorn pods require privileged access to manage storage). For example, adding the following labels to the namespace that is running Longhorn pods:
```
apiVersion: v1
kind: Namespace
metadata:
  name: longhorn-system
  labels:
    pod-security.kubernetes.io/enforce: privileged
    pod-security.kubernetes.io/enforce-version: latest
    pod-security.kubernetes.io/audit: privileged
    pod-security.kubernetes.io/audit-version: latest
    pod-security.kubernetes.io/warn: privileged
    pod-security.kubernetes.io/warn-version: latest
```

Updating CSI Snapshot CRD `v1beta1` to `v1`, `v1beta1` Deprecated

The CSI snapshot CRDs v1beta1 version is being deprecated and replaced by v1 version, please follow the instruction Enable CSI Snapshot Support to update CSI snapshot CRDs and CSI snapshot controller. If you have manifests or scripts that are still using v1beta1 version, consider upgrading them to use v1 as well.

Add StorageClass Parameter `mkfsParams` and Custom mkfs.ext4 parameters Setting Deprecated

The Custom mkfs.ext4 parameters will be deprecated and replaced by a new parameter mkfsParams as a per-StorageClass mkfs option (e.g., -I 256 -b 4096 -O ^metadata_csum,^64bit).

Longhorn Supports Fast Replica Rebuilding, and It Is Enabled by Default

Fast replica rebuilding is supported by Longhorn, and is enabled by default. The feature relies on the change timestamps and checksums of snapshot disk files, so snapshot-data-integrity is also set to fast-check. The file checksums for snapshot disks will be calculated periodically, with a default check period of 7 days. For more information, please refer to Fast Replica Rebuild and Snapshot Data Integrity Check.

Each Kubernetes Node Must Have a Unique Hostname for RWX Volumes

Longhorn has a dedicated recovery backend service for NFS servers in the share-manager pods used by the RWX volumes. The clients’ information, including its hostname, will be stored in the recovery backend. The information will be used for connection recovery if the share-manager pod is abnormally terminated and a new one is created. The environment check script helps users to check all nodes have unique hostnames. More information please refer to ReadWriteMany (RWX) Volume.

Node Drain Policy

We introduce a new setting Node Drain Policy which will deprecate the old setting Allow Node Drain with the Last Healthy Replica, so it is recommended to keep the old setting Allow Node Drain with the Last Healthy Replica as default false value and use the new setting Node Drain Policy which has more options and controls.

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