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Celestia Light Node

Light nodes are the most efficient way to interact with the Celestia network. They perform data availability sampling to verify that block data is available without downloading the entire block.

What is a Light Node?​

A Celestia Light Node:

  • Downloads block headers but not the full block data
  • Performs data availability sampling to verify block data availability
  • Requires minimal resources (storage and bandwidth)
  • Provides security guarantees through fraud proofs
  • Can submit transactions and query network state

System Requirements​

System Requirements

Minimum Requirements

  • CPU: 1 core
  • RAM: 2 GB
  • Storage: 25 GB SSD
  • Network: 100 Mbps

Recommended Requirements

  • CPU: 2 cores
  • RAM: 4 GB
  • Storage: 50 GB SSD
  • Network: 100 Mbps

Prerequisites​

Ensure you have completed the Installation guide before proceeding.

Initialize Light Node​

Initialize light node
celestia light init --p2p.network blockspacerace
Backup Your Keys

Save the address and mnemonic phrase displayed after initialization! You'll need them to recover your node.

Configuration​

Basic Configuration​

Edit configuration
# Open configuration file
nano ~/.celestia-light-blockspacerace-0/config.toml

Key Configuration Options​

[Core]
# Core node RPC endpoint
IP = "127.0.0.1"
RPCPort = "26657"
GRPCPort = "9090"

[P2P]
# Network to connect to
Network = "blockspacerace"
# Listen address
ListenAddresses = ["/ip4/0.0.0.0/tcp/2121"]

[RPC]
# RPC server settings
Address = "127.0.0.1"
Port = "26658"

[Gateway]
# Gateway API settings
Address = "127.0.0.1"
Port = "26659"
Enabled = true

Start the Light Node​

Manual Start​

Start light node manually
celestia light start --p2p.network blockspacerace

Service Setup​

Service Management Commands

Start service
sudo systemctl start celestia-light
Stop service
sudo systemctl stop celestia-light
Restart service
sudo systemctl restart celestia-light
Check status
sudo systemctl status celestia-light

Verification​

Check Node Status​

Check if node is running
# Check service status
sudo systemctl status celestia-light

# Check if RPC is responding
curl -X GET http://localhost:26658/head

Check Sync Status​

Check sync status
celestia light header sync-state --p2p.network blockspacerace

Expected output when synced:

{
  "result": {
    "id": 1,
    "height": 123456,
    "from_height": 1,
    "to_height": 123456,
    "from_hash": "A1B2C3...",
    "to_hash": "D4E5F6...",
    "start": "2023-10-01T10:00:00Z",
    "end": "2023-10-01T10:05:00Z"
  }
}

API Usage​

Basic API Calls​

Test API endpoints
# Get latest header
curl -X GET http://localhost:26658/head

# Get header by height
curl -X GET http://localhost:26658/header/123456

# Submit blob data
curl -X POST http://localhost:26658/submit_pfb -H "Content-Type: application/json" -d '{
  "namespace_id": "0c204d39600fddd3",
  "data": "SGVsbG8gQ2VsZXN0aWE=",
  "gas_limit": 80000,
  "fee": 2000
}'

JavaScript SDK Example​

Connect with JS SDK
import { NodeHttpRpc } from "@celestiaorg/celestia-rpc";

const rpc = new NodeHttpRpc("http://localhost:26658");

// Get latest header
const header = await rpc.header.get();
console.log("Latest height:", header.height);

// Submit blob
const blob = {
namespace: new Uint8Array([0, 0, 0, 0, 0, 0, 0, 1]),
data: new TextEncoder().encode("Hello Celestia!")
};

const response = await rpc.blob.submit([blob], {
fee: 2000,
gasLimit: 80000
});
console.log("Blob submitted:", response);

Monitoring​

Log Analysis​

Monitor logs
# Follow logs in real-time
sudo journalctl -fu celestia-light

# Check for errors
sudo journalctl -u celestia-light | grep -i error

# Check sync progress
sudo journalctl -u celestia-light | grep -i "syncing"

Key Metrics to Monitor​

  • Sync Height: Should match network height
  • Peer Count: Should maintain stable connections
  • Sampling Rate: Data availability sampling success rate
  • API Response Time: RPC endpoint performance

Troubleshooting​

Common Issues​

Node Not Syncing​

Check peers and connectivity
# Check peer connections
celestia light p2p peers --p2p.network blockspacerace

# Reset and restart if needed
sudo systemctl stop celestia-light
celestia light unsafe-reset-store --p2p.network blockspacerace
sudo systemctl start celestia-light

RPC Not Responding​

Check RPC configuration
# Verify RPC is enabled in config
grep -A 5 "[RPC]" ~/.celestia-light-blockspacerace-0/config.toml

# Check if port is listening
netstat -tulpn | grep :26658

# Test local connection
curl -v http://localhost:26658/head

High Resource Usage​

Optimize resource usage
# Check disk usage
du -sh ~/.celestia-light-blockspacerace-0/

# Prune old data (if supported)
celestia light prune --p2p.network blockspacerace

# Monitor resource usage
htop
iotop

Security Best Practices​

  1. Firewall Configuration

    • Only expose necessary ports (26658 for RPC, 2121 for P2P)
    • Use firewall rules to limit access

  2. Key Management

    • Backup your node keys regularly
    • Store mnemonics securely offline
    • Use hardware security modules for production

  3. Monitoring

    • Set up alerts for node downtime
    • Monitor for unusual network activity
    • Keep software updated

Next Steps​

Resources​