[pve-devel] [PATCH installer 0/6] fix #5811: add option to retrieve FQDN from DHCP configuration

[Daniel Kral]

On 3/27/25 16:17, Christoph Heiss wrote:
> Fixes #5811 [0].
> 
> Adds a new option to the answer file for specifying to use the
> DHCP-provided hostname and domain. For the domain, an additional
> fallback/default can be specified, in case the DHCP server only provides
> hostnames. The hostname is always required in this mode.
> 
> The addition to the answer file format is done in a backwards-compatible
> way.
> 
> Users can now specify the following to use the DHCP-provided domain:
> 
> ```
> [global]
> fqdn.source = "from-dhcp"
> ```
> 
> or additionally with a custom domain:
> 
> ```
> [global.fqdn]
> source = "from-dhcp"
> domain = "custom.domain.local"
> ```
> 
> Patches #1 through #4 can all be applied independently, #1 & #4 are pure
> cleanups.
> 
> [0] https://bugzilla.proxmox.com/show_bug.cgi?id=5811
> 
> Diffstat
> ========
> 
> Christoph Heiss (6):
>    auto: utils: avoid a force unwrap()
>    auto: tests: parse-answer: allow per-test runtime env
>    auto: tests: allow testing for serde parse errors of answer files
>    tui, common: move network option tests to correct crate
>    common: options: allow user-supplied domain for network options
>    fix #5811: auto: add option to retrieve FQDN from DHCP configuration

Tested this patch series with setting up a DHCP server through dnsmasq, 
where I set up the dnsmasq with `dhcp-fqdn` and `domain=something.com` 
for the domain part, and `dhcp-host=<MAC>,<IPaddr>,<HOSTNAME>`.

I tested `global.fqdn.source = 'from-dhcp'` with both 
`global.fqdn.domain` set and unset for:

- not setting hostnames nor domain at all -> correctly errors for both,
- setting a hostname but no domain -> correctly errors for unset domain, 
works as expected with fallback domain,
- setting no hostname but a domain -> correctly errors for both,
- setting both a hostname and a domain -> works as expected.

Also tested that for the working cases these are set as the fqdn after 
installation, and also tested that setting `fqdn = "some.local.domain"` 
also still works as expected as before.

Works great!

Just wanted to ask: Would it make sense to also have a fallback for the 
hostname if the DHCP server does only provide a domain but no hostname 
here or should the DHCP provide the full FQDN?

Else, consider this series as:

Tested-by: Daniel Kral <d.kral at proxmox.com>