[openstack-dev] [kolla] [bifrost] bifrost container.

Steven Dake (stdake) stdake at cisco.com
Mon May 9 21:41:22 UTC 2016

From: Devananda van der Veen <devananda.vdv at gmail.com<mailto:devananda.vdv at gmail.com>>
Reply-To: "OpenStack Development Mailing List (not for usage questions)" <openstack-dev at lists.openstack.org<mailto:openstack-dev at lists.openstack.org>>
Date: Monday, May 9, 2016 at 1:12 PM
To: "OpenStack Development Mailing List (not for usage questions)" <openstack-dev at lists.openstack.org<mailto:openstack-dev at lists.openstack.org>>
Subject: Re: [openstack-dev] [kolla] [bifrost] bifrost container.

On Fri, May 6, 2016 at 10:56 AM, Steven Dake (stdake) <stdake at cisco.com<mailto:stdake at cisco.com>> wrote:

Thanks for taking this on :)  I didn't know you had such an AR :)

From: "Mooney, Sean K" <sean.k.mooney at intel.com<mailto:sean.k.mooney at intel.com>>
Reply-To: "OpenStack Development Mailing List (not for usage questions)" <openstack-dev at lists.openstack.org<mailto:openstack-dev at lists.openstack.org>>
Date: Friday, May 6, 2016 at 10:14 AM
To: "OpenStack Development Mailing List (not for usage questions)" <openstack-dev at lists.openstack.org<mailto:openstack-dev at lists.openstack.org>>
Subject: [openstack-dev] [kolla] [bifrost] bifrost container.

Hi everyone.

Following up on my AR from the kolla host repository session
I started working on creating a kolla bifrost container.

Are some initial success it have hit a roadblock with the current install playbook provided by bifrost.
In particular the install playbook both installs the ironic dependencies and configure and runs the services.

What I'd do here is ignore the install playbook and duplicate what it installs.  We don't want to install at run time, we want to install at build time.  You weren't clear if that is what your doing.

That's going to be quite a bit of work. The bifrost-install playbook does a lot more than just install the ironic services and a few system packages; it also installs rabbit, mysql, nginx, dnsmasq *and* configures all of these in a very specific way. Re-inventing all of this is basically re-inventing Bifrost.

Sean's latest proposal was splitting this one operation into three smaller decomposed steps.

The reason we would ignore the install playbook is because it runs the services.  We need to run the services in a different way.

Do you really need to run them in a different way? If it's just a matter of "use a different init system", I wonder how easily that could be accomodated within the Bifrost project itself.... If there's another reason, please elaborate.

To run in a container, we cannot use systemd.  This leaves us with supervisord, which certainly can and should be done in the context of upstream bifrost.

 This will (as we discussed at ODS) be a fat container on the underlord cloud – which I guess is ok.  I'd recommend not using systemd, as that will break systemd systems badly.  Instead use a different init system, such as supervisord.

The installation of ironic and its dependencies would not be a problem but the ansible service module is not cable able of starting the
Infrastructure services (mysql,rabbit …) without a running init system which is not present during the docker build.

When I created a biforst container in the past is spawned a Ubuntu upstart container then docker exec into the container and ran
Bifrost install script. This works because the init system is running and the service module could test and start the relevant services.

This leave me with 3 paths forward.

1.       I can continue to try and make the bifrost install script work with the kolla build system by using sed to modify the install playbook or try start systemd during the docker build.

2.       I can use the kolla build system to build only part of the image

a.        the bifrost-base image would be build with the kolla build system without running the bifrost playbook. This
would allow the existing allow the existing features of the build system such as adding headers/footers to be used.

b.      After the base image is built by kolla I can spawn an instance of bifrost-base with systemd running

c.       I can then connect to this running container and run the bifrost install script unmodified.

d.      Once it is finished I can stop the container and export it to an image “bifros-postinstall”.

e.      This can either be used directly (fat container) or as the base image for other container that run each of the ironic services (thin containers)

3.       I can  skip the kolla build system entirely and create a script/playbook that will build the bifrost container similar to 2.

Make a supervisord set of init scripts and make the docker file do what it was intended – install the files.  This is kind of a mashup of your 1-3 ideas.  Good thinking :)

While option 1 would fully use the kolla build system It is my least favorite as it is both hacky and complicated to make work.
Docker really was not designed to run systemd as part of docker build.

For option 2 and 3 I can provide a single playbook/script that will fully automate the build but the real question I have
Is should I use the kolla build system to make the base image or not.

If anyone else has suggestion on how I can progress  please let me know but currently I am leaning towards option 2.

If you have questions about my suggestion to use supervisord, hit me up on IRC.  Ideally we would also contribute these init scripts back into bifrost code base assuming they want them, which I think they would.  Nobody will run systemd in a container, and we all have an interest in seeing BiFrost as the standard bare metal deployment model inside or outside of containers.


The only other option I see would be to not use a container and either install biforst on the host or in a vm.
GROAN – one advantage containers provide us is not mucking up the host OS with a bajillion dependencies.  I'd like to keep that part of Kolla intact :)

Right - don't install it on the host, but what's the problem with running it in a VM?

FWIW, I already run Bifrost quite successfully in a VM in each of my environments.

There isn't a super specific problem with running it in a VM other than Kolla is about containers not VMs.  OpenStack can obviously be run in a VM – our major reason for wanting containers is upgradability which Vms don't offer atomically.

That said, we could run in a VM initially and over time port to run in a container.  What we are after long term is a container–based approach to bifrost in upstream bifrost, not replicating or duplicating a bunch of work.

I believe Sean's approach of splitting out the 3 separate steps makes logical sense (to me) in the sense that the one major installation step is broken into the separate build & deploy steps that Kolla uses.

Hope that helps


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