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 <[email protected]> > > To: [email protected], > > 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. _______________________________________________ OpenStack-dev mailing list [email protected] http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
