system_health | Kusama RPC Docs

Check node health status on Kusama. Returns peer count, sync status, and connectivity — essential for monitoring, load balancing, and infrastructure management on Polkadot's canary network for real-world testing with live economic conditions.

Returns the health status of the Kusama node, including peer count, sync state, and whether the node expects to have peers.

Why Kusama? Build on Polkadot's canary network for real-world testing with live economic conditions with 7-day governance cycles (vs 1 month on Polkadot), lower bonding requirements, live KSM token economy, and first-to-market feature testing.

When to Use This Method

system_health is essential for experimental dApp developers, parachain teams, and early adopters validating new features:

Health Checks — Monitor node availability and readiness before routing traffic on Kusama
Load Balancing — Route requests only to healthy, fully synced nodes for parachain experimentation, early feature deployment, and production-grade testing with real value
Sync Status — Verify a node is caught up before trusting its state queries
Infrastructure Alerts — Trigger alerts when peers drop or sync stalls

Code Examples

Common Use Cases

1. Readiness Probe for Kubernetes

Use as a health check endpoint for container orchestration on Kusama:

JavaScript

import express from 'express';
import { ApiPromise, WsProvider } from '@polkadot/api';

const app = express();
const provider = new WsProvider('wss://kusama-rpc.n.dwellir.com');
const api = await ApiPromise.create({ provider });

app.get('/healthz', async (req, res) => {
  try {
    const health = await api.rpc.system.health();
    const isReady = !health.isSyncing.isTrue && health.peers.toNumber() > 0;

    if (isReady) {
      res.status(200).json({ status: 'healthy', peers: health.peers.toNumber() });
    } else {
      res.status(503).json({
        status: 'not ready',
        syncing: health.isSyncing.isTrue,
        peers: health.peers.toNumber()
      });
    }
  } catch (error) {
    res.status(503).json({ status: 'unreachable', error: error.message });
  }
});

2. Multi-Node Load Balancer

Route traffic only to healthy Kusama nodes:

JavaScript

async function selectHealthyNode(endpoints) {
  const results = await Promise.allSettled(
    endpoints.map(async (endpoint) => {
      const response = await fetch(endpoint, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({
          jsonrpc: '2.0',
          method: 'system_health',
          params: [],
          id: 1
        })
      });

      const { result } = await response.json();
      return { endpoint, ...result };
    })
  );

  const healthy = results
    .filter(r => r.status === 'fulfilled' && !r.value.isSyncing)
    .map(r => r.value)
    .sort((a, b) => b.peers - a.peers);

  return healthy.length > 0 ? healthy[0].endpoint : null;
}

3. Continuous Health Monitor

Periodically check node health and alert on degradation:

Python

import requests
import time

def monitor_health(endpoint, interval=30, min_peers=5):
    while True:
        try:
            payload = {
                'jsonrpc': '2.0',
                'method': 'system_health',
                'params': [],
                'id': 1
            }

            response = requests.post(endpoint, json=payload, timeout=5)
            health = response.json()['result']

            peers = health['peers']
            syncing = health['isSyncing']

            if syncing:
                print(f'WARNING: Node is syncing (peers: {peers})')
            elif peers < min_peers:
                print(f'WARNING: Low peer count: {peers}')
            else:
                print(f'OK: peers={peers}, syncing={syncing}')

        except Exception as e:
            print(f'ERROR: Node unreachable — {e}')

        time.sleep(interval)

monitor_health('https://kusama-rpc.n.dwellir.com')

Error Handling

Error Code	Description	Solution
-32603	Internal error	Node may be starting up — retry after delay
-32601	Method not found	Verify the node exposes the `system` RPC module
HTTP 429 / -32029	Rate limit exceeded	Reduce polling frequency and retry with backoff
Connection refused	Node is down	Check node process and network connectivity

system_version — Get node software version
system_chain — Get chain name
system_syncState — Get detailed sync progress
system_peers — Get detailed peer information

system_health - Kusama RPC Method