Open Stack

On 15/10/14 06:13, Thomas Spatzier wrote:
> Hi all,
>
> I have been experimenting a lot with Heat software config to  check out
> what works today, and to think about potential next steps.
> I've also worked on an internal project where we are leveraging software
> config as of the Icehouse release.
>
> I think what we can do now from a user's perspective in a HOT template is
> really nice and resonates well also with customers I've talked to.
> One of the points where we are constantly having issues, and also got some
> push back from customers, are the requirements on the in-instance tools and
> the process of building base images.
> One observation is that building a base image with all the right stuff
> inside sometimes is a brittle process; the other point is that a lot of
> customers do not like a lot of requirements on their base images. They want
> to maintain one set of corporate base images, with as little modification
> on top as possible.
>
> Regarding the process of building base images, the currently documented way
> [1] of using diskimage-builder turns out to be a bit unstable sometimes.
> Not because diskimage-builder is unstable, but probably because it pulls in
> components from a couple of sources:
> #1 we have a dependency on implementation of the Heat engine of course (So
> this is not pulled in to the image building process, but the dependency is
> there)
> #2 we depend on features in python-heatclient (and other python-* clients)
> #3 we pull in implementation from the heat-templates repo
> #4 we depend on tripleo-image-elements
> #5 we depend on os-collect-config, os-refresh-config and os-apply-config
> #6 we depend on diskimage-builder itself
>
> Heat itself and python-heatclient are reasonably well in synch because
> there is a release process for both, so we can tell users with some
> certainty that a feature will work with release X of OpenStack and Heat and
> version x.z.y of python-heatclient. For the other 4 sources, success
> sometimes depends on the time of day when you try to build an image
> (depending on what changes are currently included in each repo). So
> basically there does not seem to be a consolidated release process across
> all that is currently needed for software config.
>
> The ideal solution would be to have one self-contained package that is easy
> to install on various distributions (an rpm, deb, MSI ...).
> Secondly, it would be ideal to not have to bake additional things into the
> image but doing bootstrapping during instance creation based on an existing
> cloud-init enabled image. For that we would have to strip requirements down
> to a bare minimum required for software config. One thing that comes to my
> mind is the cirros software config example [2] that Steven Hardy created.
> It is admittedly no up to what one could do with an image built according
> to [1] but on the other hand is really slick, whereas [1] installs a whole
> set of things into the image (some of which do not really seem to be needed
> for software config).

Building an image from git repos was the best chance of having a single 
set of instructions which works for most cases, since the tools were not 
packaged for debian derived distros. This seems to be improving though; 
the whole build stack is now packaged for Debian Unstable, Testing and 
also Ubuntu Utopic (which isn't released yet). Another option is 
switching the default instructions to installing from pip rather than 
git, but that still gets into distro-specific quirks which complicate 
the instructions. Until these packages are on the recent releases of 
common distros then we'll be stuck in this slightly awkward situation.

I wrote a cloud-init boot script to install the agents from packages 
from a pristine Fedora 20 [3] and it seems like a reasonable approach 
for when building a custom image isn't practical. Somebody submitting 
the equivalent for Debian and Ubuntu would be most welcome. We need to 
decide whether *everything* should be packaged or if some things can be 
delivered by cloud-init on boot (os-collect-config.conf template, 
55-heat-config, the actual desired config hook...)

I'm all for there being documentation for the different ways of getting 
the agent and hooks onto a running server for a given distro. I think 
the hot-guide would be the best place to do that, and I've been making a 
start on that recently [4][5] (help welcome!). The README in [1] should 
eventually refer to the hot-guide once it is published so we're not 
maintaining multiple build instructions.

> Another issue that comes to mind: what about operating systems not
> supported by diskimage-builder (Windows), or other hypervisor platforms?
The Cloudbase folk have contributed some useful cloudbase-init templates 
this cycle [6], so that is a start.  I think there is interest in 
porting os-*-config to Windows as the way of enabling deployment 
resources (help welcome!).
> Any, not really suggestions from my side but more observations and
> thoughts. I wanted to share those and raise some discussion on possible
> options.
Thanks Thomas, that was useful.

cheers

>
> [1]
> https://github.com/openstack/heat-templates/blob/master/hot/software-config/elements/README.rst
> [2]
> https://github.com/openstack/heat-templates/tree/master/hot/software-config/example-templates/cirros-example
[3] 
https://review.openstack.org/#/c/119282/1/hot/software-config/example-templates/pristine-image/install_config_agent.sh
[4] 
http://git.openstack.org/cgit/openstack/openstack-manuals/tree/doc/hot-guide/source/software_deployment.rst
[5] https://review.openstack.org/#/c/127109/
[6] http://git.openstack.org/cgit/openstack/heat-templates/tree/hot/Windows

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