doc: update README.md

ref: longhorn/longhorn 6914

Signed-off-by: James Lu <james.lu@suse.com>

README.md

@@ -4,71 +4,91 @@ Longhorn Manager
 
 Manager for Longhorn.
 
-## Requirement
+## Requirements
 
-1. Existing Kubernetes Cluster 1.16+.
-2. Make sure `iscsiadm`/`open-iscsi` has been installed on the host.
+- Kubernetes cluster:
+  - Kubernetes v1.21 or later is installed.
+  - [Mount propagation](https://kubernetes-csi.github.io/docs/deploying.html#enabling-mount-propagation) is enabled.
+- Host:
+  - `iscsiadm`/`open-iscsi` and `nfs-common`/`nfs-utils`/`nfs-client` are installed.
+  - The filesystem (ext4 or XFS) supports the `file extents` feature for data storage.
+
+Run the [environment_check.sh](https://raw.githubusercontent.com/longhorn/longhorn/master/scripts/environment_check.sh) script to check if your system meets the listed requirements. For more information, see the [Longhorn documentation](https://longhorn.io/docs/latest/deploy/install/#installation-requirements).
 
 ## Build
 
 `make`
 
 ## Deployment
 
-`kubectl create -Rf deploy/install`
+- `kubectl create -f https://raw.githubusercontent.com/longhorn/longhorn/master/deploy/longhorn.yaml`
 
 It will deploy the following components in the `longhorn-system` namespace:
-1. Longhorn Manager
-2. Longhorn Flexvolume Driver for Kubernetes
-3. Longhorn UI
+
+- Longhorn Manager
+- Longhorn Instance Manager
+- Longhorn CSI plugin components
+- Longhorn UI
+
+For more information, see the [Longhorn documentation](https://longhorn.io/docs/latest/deploy/install/).
 
 ## Cleanup
 
 Longhorn CRD has finalizers in them, so user should delete the volumes and related resource first, give manager a chance to clean up after them.
 
 To prevent damage to the Kubernetes cluster, we recommend deleting all Kubernetes workloads using Longhorn volumes (PersistentVolume, PersistentVolumeClaim, StorageClass, Deployment, StatefulSet, DaemonSet, etc).
 
-1. Create the uninstallation job to cleanly purge CRDs from the system and wait for success:
-  ```
-  kubectl create -f deploy/uninstall/uninstall.yaml
-  kubectl get job/longhorn-uninstall -w
-  ```
+1. Ensure that the value of the Longhorn setting `deleting-confirmation-flag` is `true`.
 
-Example output:
+```bash
+kubectl -n longhorn-system edit setting deleting-confirmation-flag
 ```
-$ kubectl create -f https://raw.githubusercontent.com/rancher/longhorn/master/uninstall/uninstall.yaml
+
+2. Create the uninstallation job to cleanly purge CRDs from the system. Verify that uninstallation was successful.
+
+```bash
+kubectl create -f https://raw.githubusercontent.com/longhorn/longhorn/master/uninstall/uninstall.yaml
+kubectl get job/longhorn-uninstall -w
+```
+
+Example output:
+
+```bash
+$ kubectl create -f https://raw.githubusercontent.com/longhorn/longhorn/master/uninstall/uninstall.yaml
 serviceaccount/longhorn-uninstall-service-account created
 clusterrole.rbac.authorization.k8s.io/longhorn-uninstall-role created
 clusterrolebinding.rbac.authorization.k8s.io/longhorn-uninstall-bind created
 job.batch/longhorn-uninstall created
 
-$ kubectl get job/longhorn-uninstall -w
+$ kubectl -n longhorn-system get job/longhorn-uninstall -w
 NAME                 COMPLETIONS   DURATION   AGE
 longhorn-uninstall   0/1           3s         3s
 longhorn-uninstall   1/1           20s        20s
 ^C
 ```
 
-2. Remove remaining components:
-  ```
-  kubectl delete -Rf deploy/install
-  kubectl delete -f deploy/uninstall/uninstall.yaml
-  ```
+3. Remove remaining components.
+
+```bash
+kubectl delete -f https://raw.githubusercontent.com/longhorn/longhorn/master/uninstall/uninstall.yaml
+kubectl delete -f https://raw.githubusercontent.com/longhorn/longhorn/master/deploy/longhorn.yaml
+
+```
 
 Tip: If you try `kubectl delete -Rf deploy/install` first and get stuck there, pressing `Ctrl C` then running `kubectl create -f deploy/uninstall/uninstall.yaml` can also help you remove Longhorn. Finally, don't forget to cleanup remaining components by running `kubectl delete -f deploy/uninstall/uninstall.yaml`.
 
 ## Unit Test
 
 To execute all unit tests, make sure there are no uncommitted changes and run:
 
-```
+```bash
 make test
 ```
 
 If there are uncommitted changes, only the affected modules will be tested.
 To execute specific unit tests or all tests matching a regex, run:
 
-```
+```bash
 TESTS=="NodeControllerSuite.*" make test
 ```
 
@@ -81,7 +101,8 @@ See [longhorn-tests repo](https://github.com/rancher/longhorn-tests/tree/master/
 Please check [the Longhorn repo](https://github.com/longhorn/longhorn#community) for the contributing guide.
 
 ## License
-Copyright (c) 2014-2021 The Longhorn Authors
+
+Copyright (c) 2014-2024 The Longhorn Authors
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.