Floating IP Addresses

What Is a Floating IP?

A floating IP is a static public IP address that can be instantly reassigned between servers. Use it to:

• Perform zero-downtime server migrations
• Implement manual failover between primary and standby servers
• Maintain a stable IP while replacing the underlying server

Reserving a Floating IP

1. Go to Network → Floating IPs → Reserve IP.
2. Choose a region.
3. The IP is reserved immediately.

Cost: $0.005/hr (~$3.60/month) while reserved but unattached.

Attaching to a Server

1. Go to Network → Floating IPs → [Your IP] → Attach.
2. Select the target server.
3. The IP is routed to the server within seconds.

Configuring the OS

The floating IP must be configured on the server's loopback interface:

$# Ubuntu 22.04
$ip addr add <FLOATING_IP>/32 dev lo

Make persistent:

$cat >> /etc/netplan/99-floating.yaml << EOF
$network:
$  version: 2
$  ethernets:
$    lo:
$      addresses:
$        - <FLOATING_IP>/32
$EOF
$netplan apply

Failover Script Example

$#!/bin/bash
$# Run on the standby server to claim the floating IP
$
$FLOATING_IP="203.0.113.100"
$SERVER_ID="your-standby-server-id"
$API_KEY="your-api-key"
$
$curl -X POST "https://api.lightyear.host/v1/floating-ips/$FLOATING_IP/attach"   -H "Authorization: Bearer $API_KEY"   -d "server_id=$SERVER_ID"