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Alex Spinov
Alex Spinov

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Longhorn Has a Free API — Cloud-Native Storage for Kubernetes

#kubernetes #storage #api #devops

Longhorn is the CNCF lightweight distributed block storage system for Kubernetes. It turns your cluster nodes' disks into a highly available storage pool with snapshots, backups, and disaster recovery.

Free, open source, and backed by SUSE/Rancher. No license keys, no storage fees.

Why Use the Longhorn API?

  • Distributed block storage — replicated across nodes for HA
  • Automated snapshots — recurring snapshot schedules via API
  • Disaster recovery — backup to S3/NFS with one API call
  • Volume management — create, resize, and clone volumes programmatically

Quick Setup

1. Install Longhorn 

helm repo add longhorn https://charts.longhorn.io
helm install longhorn longhorn/longhorn --namespace longhorn-system --create-namespace

# Access UI
kubectl port-forward -n longhorn-system svc/longhorn-frontend 8080:80
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2. List Volumes 

LONGHORN_URL="http://localhost:8080"

curl -s "$LONGHORN_URL/v1/volumes" | jq '.data[] | {name: .name, size: .size, state: .state, robustness: .robustness, replicas: (.numberOfReplicas)}'
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3. Create a Volume 

curl -s -X POST "$LONGHORN_URL/v1/volumes" \
  -H "Content-Type: application/json" \
  -d '{"name":"my-data-vol","size":"10Gi","numberOfReplicas":3,"frontend":"blockdev"}'
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4. Create a Snapshot 

curl -s -X POST "$LONGHORN_URL/v1/volumes/my-data-vol?action=snapshotCreate" \
  -H "Content-Type: application/json" \
  -d '{"name":"backup-before-upgrade"}'
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5. Backup to S3 

# First configure backup target in settings
curl -s -X PUT "$LONGHORN_URL/v1/settings/backup-target" \
  -H "Content-Type: application/json" \
  -d '{"value":"s3://my-backups@us-east-1/longhorn"}'

# Create backup from snapshot
curl -s -X POST "$LONGHORN_URL/v1/volumes/my-data-vol?action=snapshotBackup" \
  -H "Content-Type: application/json" \
  -d '{"name":"backup-before-upgrade"}'
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Python Example 

import requests

LONGHORN = "http://localhost:8080"

# List volumes
vols = requests.get(f"{LONGHORN}/v1/volumes").json()
for v in vols["data"]:
    size_gb = int(v["size"]) / (1024**3)
    print(f"Volume: {v['name']} | Size: {size_gb:.0f}GB | State: {v['state']} | Replicas: {v['numberOfReplicas']}")

# List nodes
nodes = requests.get(f"{LONGHORN}/v1/nodes").json()
for n in nodes["data"]:
    conditions = {c['type']: c['status'] for c in n.get('conditions', [])}
    print(f"Node: {n['name']} | Schedulable: {n.get('allowScheduling')} | Ready: {conditions.get('Ready','?')}")
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Key Endpoints

Use Case Endpoint Method
List volumes /v1/volumes GET
Create volume /v1/volumes POST
Snapshot /v1/volumes/{name}?action=snapshotCreate POST
Backup /v1/volumes/{name}?action=snapshotBackup POST
List nodes /v1/nodes GET
List backups /v1/backupvolumes GET
Settings /v1/settings GET/PUT
Recurring jobs /v1/recurringjobs GET/POST

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