Date: Sun, 11 Sep 2022 02:22:59 +0900 From: Tomoaki AOKI <junchoon@dec.sakura.ne.jp> To: Guido Falsi <mad@madpilot.net> Cc: freebsd-hackers@freebsd.org Subject: Re: Dynamic hostname in rc.conf (for bhyve VMs) Message-ID: <20220911022259.a51af1f585f24af6bfb6d4e4@dec.sakura.ne.jp> In-Reply-To: <f76151eb-8374-5691-b158-d3c7be9f6169@madpilot.net> References: <f76151eb-8374-5691-b158-d3c7be9f6169@madpilot.net>
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On Sat, 10 Sep 2022 10:52:01 +0200 Guido Falsi <mad@madpilot.net> wrote: > Hi, > > Since rc.conf is just a shell script I'd like to be able to set hostname > dynamically. > > This is bhyve related because what I'd like to do is pass an hostname to > VMs via the -e option to bhyveload(8), and then read it in rc.conf, > maybe via sysctl to set the hostname accordingly. > > By the way I'm using vm-bhyve [1] to manage my VMs. its configuration > files are also shell scripts, so I was planning to hack some simple > logic there, host side, to derive the hostname from filesystem (useful > for cloned VMs). > > Could not find any example or documentation about any step of this. > > Is this even possible with current tools? I'm open to hacky solutions to > start with, then maybe refine them. > > > I'm trying to do this because I'm using a local dnsmasq that exposes DNS > with the hostnames provided by VMs, but clones get the same naem as the > machien they're cloned from and mask those in this small internal DNS. > If each clone could provide it's different name it would be much better. > > > Thanks in advance for any help/suggestions. > > > [1] https://github.com/churchers/vm-bhyve > > -- > Guido Falsi <mad@madpilot.net> > IIUC, and if you obtain IP addresses of each VMs via DHCP, just keeping hostname on rc.conf would be suffice. /etc/rc.d/hostname has a functionality to get hostname by hostname=`/bin/kenv dhcp.host-name`, meaning hostname is set using what DHCP server supplied, if NOT in a jail. See the script for details. -- Tomoaki AOKI <junchoon@dec.sakura.ne.jp>
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