[openstack-dev] Unified Guest Agent, PoC for os-collect-config

Clint Byrum clint at fewbar.com
Tue Jan 21 23:38:41 UTC 2014

Excerpts from Dmitry Mescheryakov's message of 2014-01-21 09:30:17 -0800:
> Hello folks,
> At the end of the previous discussion on the topic [1] I've decided to make
> a PoC based on oslo.messaging. Clint suggested and I agreed to make it for
> os-collect-config. Actually I've made a PoC for Savanna first :-) but
> anyway here is the one for os-collect-config [2].
> I've made a couple of observations:
> First, the os-collect-config naturally becomes an RPC server. That gives an
> advantage of having feedback, i.e. knowing that the desired config was
> actually received and applied.
> Second, with the oslo.messaging approach seems like there is almost nothing
> to extract to common code. It is rather well seen on the minimal example
> like os-config-apply. I thought there would be something to share between
> projects using the agent, but so far it
> looks like oslo.messaging already covers all the needs. Which IMHO is great!
> So, any thoughts?

Pretty cool! Thanks for diving down this rabbit hole Dmitry.

I have a few thoughts:

I had originally thought that RPC would just become another collector. One
that is updated more actively. The loss of ec2/cfn/heat_local means that
this can't be used in the boot-strapping of the RPC itself the way we
use heat_local right now to bootstrap cfn.

However, perhaps with Heat changes, cloud-init can just bootstrap the
appropriate credentials and connection information in and this tool can
just read that and only speak RPC.

Seems like the next hurdle is to change from calling a single command
with some json populated to actual plugins that implement RPC calls.
Also replies would probably be important. :)

Anyway, I'm very interested to see how this progresses. Keep us posted!

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