Re: Dynamic hostname in rc.conf (for bhyve VMs)

On 17/09/22 21:22, John Kennedy wrote:
> On Sat, Sep 10, 2022 at 10:52:01AM +0200, Guido Falsi wrote:
>> Since rc.conf is just a shell script I'd like to be able to set hostname
>> dynamically.
> 
>    AFAIK, not a shell-script (although variables are set in that syntax).

I'm sure about this, rc.conf is sourced through the shell. So it is a 
shell script.

You can verify this by checking the load_rc_config() function in 
/etc/rc.subr which runs (beyond a lot of other things):

. /etc/rc.conf


I was wrong about vm-bhyve machine configuration file, which is a simple 
key/value pair file.

> 
>    I wasn't trying to do exactly what you are, but one thing I did was set the
> MAC address as one of the bhyve options:
> 
> 	...
> 	-s 5,virtio-net,tap2,mac=00:01:02:03:04:05
> 	...
> 
>    (Changed the MAC address in the example, but pick a safe one for your setup)
> 
>    Should be able to provide your own rc.d configuration file that does
> something like do a switch on MAC and call the hostname script directly.
> 
> 

I already succeeded by adding "-e bhyve_vm_name=${_name}" (where _name 
contains the name of the vm) to bhyveload arguments, then reading it 
with kenv from rc.conf:

hostname="$(/bin/kenv bhyve_vm_name).internal.vms"


Works like a charm.

-- 
Guido Falsi <mad@madpilot.net>