Re: Guix "ops"

["Thompson, David" <dthompson2@worcester.edu>]

On Wed, May 27, 2015 at 3:41 PM, Ludovic Courtès <ludo@gnu.org> wrote:
> David Thompson <dthompson2@worcester.edu> skribis:
>
>> Ludovic Courtès <ludo@gnu.org> writes:
>>
>>> Perhaps one addition eventually would be to allow IPs to be
>>> automatically allocated and have host name lookup DTRT in each VM.
>>
>> Do you have any idea how we could do that for local VMs?  There's no
>> daemon managing the provision of these resources, so I don't know what
>> strategy can be used to automatically allocate static IPs.
>
> QEMU allows you to specify the guest’s IP, I think, and apparently it
> can create VLANs and connect several unprivileged QEMU instances
> together via -net socket (info "(qemu-doc) sec_invocation").
>
> Things like libvirt probably provide a higher-level interface to that.
> (I don’t know if it justifies the extra dependency.)

If libvirt's API was really useful, perhaps it could be an optional
dependency for users that want to deploy QEMU VMs?

>> The automagic hostname lookup part is particularly interesting to me.  A
>> more complete deployment configuration would have the web server
>> dependent on the db server.  I originally intended to handle this by
>> delaying the creation of the web server until after the db server was
>> made, and invoking a procedure that accepted the db server's state as
>> input and output the correct configuration for the web server.
>
> I’ve seen that Docker can do that.  ;-)  IIRC it populates /etc/hosts in
> each container.  That’s something we could do.  Another possibility
> would be to rely on mDNS.

If Docker can do it, so can we! :)

>> Thinking out loud here: Maybe 'guix deploy' can kick off the
>> provisioning for all machines first, and afterwards the OS configs can
>> be altered to include the correct /etc/hosts file.
>
> The transform procedure could force the right /etc/hosts in each OS, I
> suppose?

Yes.  Perhaps the extensibility I had in mind could be better achieved
by allowing additional, user specified transformations in the machine
declaration.

Thanks for your input!

- Dave