[Bug] Different A record for nodes with the same name

[nblock]

Is this a support request?

• This is not a support request

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

While testing #1369 (comment), I noticed the following behavior:

Setup

• Node with name laptop assigned to user alice : 100.64.0.2, fd7a:115c:a1e0::2
• Node with name laptop assigned to user bob: 100.64.0.3, fd7a:115c:a1e0::3
• Config:

  dns:
    use_username_in_magic_dns: false
    base_domain: tn.example.com

• Content of /etc/resolv.conf on both nodes:

  nameserver 100.100.100.100
  search tn.example.com
  

On alice's node

alice:~$ tailscale ip
100.64.0.2
fd7a:115c:a1e0::2

alice:~$ dig +short laptop.tn.example.com
100.64.0.3

On bob's node

bob:~$ tailscale ip
100.64.0.3
fd7a:115c:a1e0::3

bob:~$ dig +short laptop.tn.example.com
100.64.0.2

You get a different IP depending on depending on where you ask. Interestingly, Tailscale resolves to the IP of the other node.

Expected Behavior

Not sure which IP address, but I'd expect to always get the same one.

Steps To Reproduce

• Create two users
• Register a node for each user (using unique names, e.g. laptop for user alice and server for user bob)
• Run: headscale nodes rename -i ID_OF_SERVER_BOB laptop
• Node list:

$ headscale nodes list
ID | Hostname  | Name      | MachineKey | NodeKey | User  | IP addresses                  | Ephemeral | Last seen           | Expiration          | Connected | Expired
4  | laptop    | laptop    | [fLttA]    | [J2GVN] | alice | 100.64.0.2, fd7a:115c:a1e0::2 | false     | 2024-09-10 07:53:41 | 0001-01-01 00:00:00 | online    | no
5  | server    | laptop    | [BxUYW]    | [e4Bjc] | bob   | 100.64.0.3, fd7a:115c:a1e0::3 | false     | 2024-09-10 07:55:01 | 0001-01-01 00:00:00 | online    | no

Environment

- OS: Debian 12
- Headscale version: 0.23.0-beta.4
- Tailscale version: 1.72.1

Runtime environment

• Headscale is behind a (reverse) proxy
• Headscale runs in a container

Anything else?

No response

[kradalby]

Ah, I can see there is no check to validate the uniqueness of the name in the rename.

one of the nodes gets a unique name if it is not renamed right?

[nblock]

one of the nodes gets a unique name if it is not renamed right?

Yes, it looks like this when both join with the same hostname:

ID | Hostname  | Name            | MachineKey | NodeKey | User  | IP addresses                  | Ephemeral | Last seen           | Expiration          | Connected | Expired
6  | laptop    | laptop          | [SYCPl]    | [JKsUY] | alice | 100.64.0.4, fd7a:115c:a1e0::4 | false     | 2024-09-11 10:55:08 | 0001-01-01 00:00:00 | online    | no
7  | laptop    | laptop-klnwimod | [IcRoJ]    | [MjqjD] | bob   | 100.64.0.5, fd7a:115c:a1e0::5 | false     | 2024-09-11 10:55:10 | 0001-01-01 00:00:00 | online    | no

Probably a unique constraint will be required for the name column?