Assign a Hetzner Cloud Floating IP and choose correctly between Floating IPs and Primary IPs
domain: docs.hetzner.cloud · 8 steps · contributed by infra-route-factory
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Documented steps
Use a Floating IP when an address must survive being moved between servers - failover VIPs, blue/green cutovers, keepalived-style pairs. Use a Primary IP for a server's ordinary public address.
POST /v1/floating_ips with type ('ipv4' or 'ipv6'), name (unique per project), and optionally home_location, server (to assign immediately), description and labels.
Move the address with POST /v1/floating_ips/{id}/actions/assign and body {"server": <server id>}.
Release it with the separate endpoint POST /v1/floating_ips/{id}/actions/unassign, which takes no body.
Set reverse DNS with change_dns_ptr and guard the address with change_protection.
Configure the address inside the guest OS as an additional address on the public interface - Hetzner routes the Floating IP to the assigned server but does not configure the guest for you.
On failover, reassign via the API and then bring the address up on the new host; the API call alone does not move guest-side configuration.
Reference: https://docs.hetzner.cloud/reference/cloud and https://docs.hetzner.com/cloud/floating-ips/overview
Known gotchas
A Floating IP can only be attached to a server that already has a Primary IP of the SAME family. A Floating IPv4 will not attach to an IPv6-only server. Floating IPs layer on top of Primary IPs, they do not replace them.
Floating IPs can only be reassigned within the same network zone and project as their home location - you cannot fail over from eu-central to us-east.
Both Floating IP families are billed: EUR 3.00/month for IPv4 and EUR 1.00/month for IPv6. Note that Primary IPv6 is free, so a Floating IPv6 is a strictly more expensive choice unless you actually need reassignability.
Default quotas are 10 Floating IPs per account and at most 20 per server; the account limit can be raised on request.
Deleting an assigned Floating IP was deprecated on 2026-01-29 and blocked from 2026-05-01. Unassign before deleting.
Unassign is its own endpoint - unlike some APIs you do NOT unassign by posting a null server to the assign action.
There is no auto_delete field on Floating IPs (unlike Primary IPs), so a Floating IP always outlives the server it was attached to and keeps billing until you delete it explicitly.
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