How to configure NFS Backup in Longhorn using YAML

Article Number: 000021917

Environment

SUSE Rancher Longhorn

Situation

While the Longhorn UI offers a convenient way to configure backup targets and manage backups, using the CLI or YAML is often more practical in environments where the UI is unavailable—such as air-gapped setups—or when users prefer working directly with Kubernetes resources.

Resolution

Ensure that you have a running NFS server. In this example, we are using a Linux NFS server; however, it can also be a Windows NFS server. Longhorn only requires an accessible NFS share for backups.

Step 1: Configure the NFS Export on Your Server

This step involves setting up an NFS share on your chosen server where Longhorn will store its backups.

Edit the NFS exports file:
Open the /etc/exports file using a text editor with root privileges:

sudo vi /etc/exports

2. Add the NFS export line:
Add the following line to the end of the file. This example sets up /opt/longhorn-backupstore as the shared directory.

/opt/longhorn-backupstore *(rw,sync,no_subtree_check,no_root_squash)

Tip: For enhanced security, replace * with the specific Kubernetes cluster's subnet (e.g., 192.168.0.0/24) to restrict access to only your cluster nodes. Remember to create the directory /opt/longhorn-backupstore if it doesn't already exist. 3. Apply the export changes:
After saving the /etc/exports file, apply the new export rules without restarting the entire NFS service:

sudo exportfs -ra

4. Enable and restart the NFS server:
Ensure the NFS server service is enabled to start on boot and then restart it to apply all changes:

sudo systemctl enable nfs-server
sudo systemctl restart nfs-server

Step 2: Add the NFS Backup Target in Longhorn

Now, you need to configure Longhorn to recognise your newly created NFS share as a backup target. You can do this via the Longhorn UI or by applying a Kubernetes Custom Resource (CR).

Option A: Using Longhorn UI

1. Navigate to Longhorn UI:
  Open your web browser and go to the Longhorn UI.
Go to Settings:
From the left navigation pane, click on Settings.
Configure Backup Target:
Scroll down or search for the "Backup Target" setting.
- Set the target as:
  Enter the NFS server IP and the exported path, along with recommended NFS mount options. Replace <nfs-server-ip> with the actual IP address of your NFS server.
```
nfs://<nfs-server-ip>:/opt/longhorn-backupstore?nfsOptions=soft,timeo=330,retrans=3
```
  4. Credential Field: Leave the credential field empty unless your NFS server requires specific authentication. 5. Save Changes: Click Save. Longhorn will attempt to validate the connection to the NFS target. Wait for the validation to complete successfully.

Option B: Using YAML (Custom Resource)

This method involves creating a BackupTarget Custom Resource Definition (CRD) directly.

Create a YAML file (e.g., nfs-backup-target.yaml) with the following content. Remember to replace <nfs-server-ip> with the actual IP address of your NFS server.

apiVersion: longhorn.io/v1beta2
kind: BackupTarget
metadata:
  name: nfs-backup-target  # Choose a descriptive name for your backup target
  namespace: longhorn-system
spec:
  backupTargetURL: "nfs://<nfs-server-ip>:/opt/longhorn-backupstore?nfsOptions=soft,timeo=330,retrans=3"
  credentialSecret: "" # Leave empty if no credentials are required
  pollInterval: 5m0s # How often Longhorn checks the backup target for new backups

2. Apply the resource:

kubectl apply -f nfs-backup-target.yaml

3. Confirm the status:

Check if the BackupTarget resource has been created and is active:

kubectl get backuptargets -n longhorn-system

You should see an entry for nfs-backup-target (or whatever name you chose)

Step 3: Create and Trigger a Volume Backup

Once your NFS backup target is configured, you can start creating backups of your Longhorn volumes. This typically involves first creating a snapshot and then creating a backup from that snapshot.

Create a YAML file (e.g., volume-backup.yaml) to define both a snapshot and a backup. Replace <snapshot-name> and <volume-name> with appropriate values for your scenario.

apiVersion: longhorn.io/v1beta2
kind: Snapshot
metadata:
  name: <snapshot-name> # e.g., my-app-volume-snapshot-initial
  namespace: longhorn-system
spec:
  createSnapshot: true
  volume: <volume-name> # The name of the Longhorn volume you want to back up
---
apiVersion: longhorn.io/v1beta2
kind: Backup
metadata:
  name: <backup-name> # e.g., my-app-volume-backup-initial
  namespace: longhorn-system
  labels:
    backup-volume: <volume-name> # Label for easy identification
spec:
  snapshotName: <snapshot-name> # Must match the name of the snapshot created above

Note: A snapshot of the volume is always required before a backup can be triggered. The above YAML effectively creates a snapshot and then initiates a backup using that snapshot. 2. Apply the resource:

kubectl apply -f volume-backup.yaml

Step 4: Verify the Resources

After initiating a backup, you can monitor its progress and confirm its creation using kubectl commands.

Check the status of snapshots:

kubectl get snapshots.longhorn.io -n longhorn-system

Look for your snapshot; its State should eventually show Ready. 2. Check the status of backups:

kubectl get backups.longhorn.io -n longhorn-system

Monitor the State of your backup. It should progress through Creating, InProgress, and finally Completed.

Once your Backup resource shows a Completed state, your NFS backup target is functional, and the volume data has been successfully backed up to your configured NFS share.