On 11/20/2013 09:29 PM, Clint Byrum wrote: > Excerpts from Thomas Spatzier's message of 2013-11-19 23:35:40 -0800: >> Excerpts from Steve Baker's message on 19.11.2013 21:40:54: >>> From: Steve Baker <sba...@redhat.com> >>> To: openstack-dev@lists.openstack.org, >>> Date: 19.11.2013 21:43 >>> Subject: Re: [openstack-dev] [Heat] HOT software configuration >>> refined after design summit discussions >>> >> <snip> >>> I think there needs to a CM tool specific agent delivered to the server >>> which os-collect-config invokes. This agent will transform the config >>> data (input values, CM script, CM specific specialness) to a CM tool >>> invocation. >>> >>> How to define and deliver this agent is the challenge. Some options are: >>> 1) install it as part of the image customization/bootstrapping (golden >>> images or cloud-init) >>> 2) define a (mustache?) template in the SoftwareConfig which >>> os-collect-config transforms into the agent script, which >>> os-collect-config then executes >>> 3) a CM tool specific implementation of SoftwareApplier builds and >>> delivers a complete agent to os-collect-config which executes it >>> >>> I may be leaning towards 3) at the moment. Hopefully any agent can be >>> generated with a sufficiently sophisticated base SoftwareApplier type, >>> plus maybe some richer intrinsic functions. >> This is good summary of options; about the same we had in mind. And we were >> also leaning towards 3. Probably the approach we would take is to get a >> SoftwareApplier running for one CM tool (e.g. Chef), then look at another >> tool (base shell scripts), and then see what the generic parts art that can >> be factored into a base class. >> >>>>> The POC I'm working on is actually backed by a REST API which does >> dumb >>>>> (but structured) storage of SoftwareConfig and SoftwareApplier >> entities. >>>>> This has some interesting implications for managing SoftwareConfig >>>>> resources outside the context of the stack which uses them, but lets >> not >>>>> worry too much about that *yet*. >>>> Sounds good. We are also defining some blueprints to break down the >> overall >>>> software config topic. We plan to share them later this week, and then >> we >>>> can consolidate with your plans and see how we can best join forces. >>>> >>>> >>> At this point it would be very helpful to spec out how specific CM tools >>> are invoked with given inputs, script, and CM tool specific options. >> That's our plan; and we would probably start with scripts and chef. >> >>> Maybe if you start with shell scripts, cfn-init and chef then we can all >>> contribute other CM tools like os-config-applier, puppet, ansible, >>> saltstack. >>> >>> Hopefully by then my POC will at least be able to create resources, if >>> not deliver some data to servers. >> We've been thinking about getting metadata to the in-instance parts on the >> server and whether the resources you are building can serve the purpose. >> I.e. pass and endpoint to the SoftwareConfig resources to the instance and >> let the instance query the metadata from the resource. Sounds like this is >> what you had in mind, so that would be a good point for integrating the >> work. In the meantime, we can think of some shortcuts. >> > Note that os-collect-config is intended to be a light-weight generic > in-instance agent to do exactly this. Watch for Metadata changes, and > feed them to an underlying tool in a predictable interface. I'd hope > that any of the appliers would mostly just configure os-collect-config > to run a wrapper that speaks os-collect-config's interface. > > The interface is defined in the README: > > https://pypi.python.org/pypi/os-collect-config > > It is inevitable that we will extend os-collect-config to be able to > collect config data from whatever API these config applier resources > make available. I would suggest then that we not all go off and reinvent > os-collect-config for each applier, but rather enhance os-collect-config > as needed and write wrappers for the other config tools which implement > its interface. > > os-apply-config already understands this interface for obvious reasons. > > Bash scripts can use os-apply-config to extract individual values, as > you might see in some of the os-refresh-config scripts that are run as > part of tripleo. I don't think anything further is really needed there. > > For chef, some kind of ohai plugin to read os-collect-config's collected > data would make sense. > I'd definitely start with occ as Clint outlines. It would be nice if occ only had to be configured to poll metadata for the OS::Nova::Server to fetch the aggregated data for the currently available SoftwareAppliers.
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