Re: [OSSTEST Nested PATCH v8 5/7] Add new script to customize nested test configuration

[Ian Campbell <ian.campbell@citrix.com>]

On Thu, 2015-04-23 at 12:30 +0100, Ian Campbell wrote:
> This is the same problem I mentioned above arising from $l1 doing double
> duty as both host and guest. There are places in osstest which are
> pretty fluid about this (if the object has the approrpaite props you can
> use it as either), but it can be a bit confusing for the poor programmer
> or reader...
> 
> Perhaps having a
>    our $l1ho = make_nested_host($l0ho, $l1guest);
> construct, which does copies $l1guest and propagates some properties as
> above and then using $l1guest + $l1host in the appropriate places only
> would help keep things straight?

I had a thought here: would it be at all useful to add some light syntax
to the idents to help represent the nested scenario in sg-run-jobs and
to make select* behave more naturally in these cases?

e.g. "l0host:l1guest" as a host ident would, when given to selecthost,
return a $ho relating to the nested l1 hypervisor running in the guest
with ident l1guest on the physical host with ident l0host. Certain
properties of the l0host (such as dhcp-watch-method) would automatically
be applied to that host.

Along those lines ts_get_host_guest would handle ("l0host:l1guest",
"l2guest") by returning a host object for the l1 hypervisor running in
l1guest on l0host and a guest object for the l2guest. This falls out
basically for free given ts_get_host_guest just calls selecthost.

I considered whether a similar syntax for a guest ident, i.e.
"l1host:l2guest" would be useful, but given that selectguest already
takes the host (in this case that would be l1host) as an argument I
couldn't see the need.

> (Best to wait for Ian's feedback on this before doing anything, he may
> not like it)

This is still true of course...

Ian.