Open Stack

From: Steven Dake (stdake) [mailto:stdake at cisco.com]
Sent: Friday, May 6, 2016 6:56 PM
To: OpenStack Development Mailing List (not for usage questions) <openstack-dev at lists.openstack.org>
Subject: Re: [openstack-dev] [kolla] [bifrost] bifrost container.

Sean,

Thanks for taking this on :)  I didn't know you had such an AR :)
[Mooney, Sean K] well if other want to do the work that ok with me too but I was planning on deploying bifrost
At home again anyway so I taught I  might as well try to automate the process while im at it.

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
https://etherpad.openstack.org/p/kolla-newton-summit-kolla-kolla-host-repo
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.
[Mooney, Sean K] that is certainly an option but bifrost is an installer for ironic and its supporting service. Not using its installation scripts significantly reduces the value of
Integrating with bifrost vs fixing the existing ironic support in kolla and using that to provision the undercloud.

The reason we would ignore the install playbook is because it runs the services.  We need to run the services in a different way.  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.
[Mooney, Sean K] if we don't use the  bifrost install playbook then yes supervisord would be a good choice for the init system.
Looking at the official centos docker image https://hub.docker.com/_/centos/  they do provided instruction for running systemd containers tough I have had issues with this in the past.

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.

4.
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.
[Mooney, Sean K]  I have briefly used supervisord before for a pet project https://github.com/SeanMooney/docker-devstack to create a container for running devstack so it did hot pollute my host.
supervisord  is a nice tool. Im just about to head home for the weekend but I might grab you on irc on Monday to follow up.


Regards
-steve

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 :)
[Mooney, Sean K]  yes I would prefer not to break that too. This was basically the option of we don't actually do the integration and instead just tell
The user how to use bifrost to do the deployment but leave it up to them do decide how to install it. so for me that was plan Z so we have a couple of letter
Go through first.

These would essentially be a no op for kolla as we would simply have to document how to install bifrost which is covered
Quite well as part of the bifrost project.

Regards
Sean.

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