My work on Kolla

During last month I was working on one of OpenStack projects: Kolla. My job was adding support for non-x86 architectures: aarch64 and ppc64le. Also resurrecting Debian support.

A bit of background

At Linaro we work on getting AArch64 (64-bit ARM, arm64) to be present in many places. We have at least two OpenStack instances running at the moment – on AArch64 hardware only.

First we used Debian/jessie and Openstack ‘liberty’ version. Was working. Not best but we helped many projects by providing virtual machines for porting software.

It was built from packages and later (when ‘mitaka’ was released) we moved to virtualenv per component. Out second “cloud” runs that. With proper Neutron networking, live migration and few other nice things.

But virtualenvs were done as quick solution. We decided to move to Docker containers for next release.

And Kolla was chosen as a tool for it. We do not like to reinvent the wheel again and again…

Non-x86 support in Kolla

The problem was typical: Kolla being x86-64 centric. As most of software nowadays. But thanks to work done by Sajauddin Mohammad I had something to use as a base for adding aarch64 support.

I took his patch, slashed out most of it and concentrated on getting minimal changes needed to get something built on AArch64 . Effect was sent for review and is now at 10th version.

Docker images started to appear. But at beginning I was building Ubuntu ones as Debian support was “basically abandoned, on a way out”. From CentOS guys I got confirmation that official Docker image will be generated (it is done already).

I spent some time on making sure that whole non-x86 support is free from any hardcoding wherever possible. As you can see in my working branch it went quite well. Most of arch related changes are related to “distro does not provide package ZYS for that architecture” or to handling of external repositories.

Debian support

And here we come to Debian support. At Linaro we decided to support two community based distributions: CentOS and Debian. But Debian was on a way out in Kolla…

As this was not related much to non-x86 work I decided to use one of x86-64 machines for that stuff.

First builds were against ‘jessie-backports’ base tag. I had to make a patch to tell APT that if I want backports then I really want them. It was sent for review as rest of patches.

Images were building but not so many as for Ubuntu. So I went through all of them and enabled Debian where it was possible. Resulting patch went for review as usual.

Effect was quite nice (on x86-64):

  • debian-binary: 158
  • debian-source: 201

But ‘jessie’ was missing several packages even with backports enabled. So after discussion with my team I decided to drop it and go for Debian/testing ‘stretch’ one instead. It is already frozen for release so no big changes are allowed. Patch in review of course.

At that moment I abandoned one of previous patches as ‘jessie-backports’ was not something I planned to support.

Turned out that ‘stretch’ images have a bit different set of packages installed than ‘jessie’ had. So ‘gnupg’ and ‘dirmngr’ were missing while we need them for importing GPG keys into APT. Proper patch went to review again.

Did rebuild on x86-64:

  • stretch-binary: 137
  • stretch-source: 195

A bit less than ‘jessie-backports’ had, right? Sure, but it also shows that I have to make a new build to check numbers (laptop already has ~1500 docker images generated by kolla).

Cleaning of old Power patch

Remember the patch which all that started from? I did not forgot it and after building all those images I went back to it.

Some parts are just fugly so I skipped them but others were useful if done properly. That’s how new changes were done and some updates to previous ones.

Then I managed to put remote hands on one of Power machines at Red Hat and started builds:

  • debian-binary: 134
  • debian-source: 184
  • ubuntu-binary: 147
  • ubuntu-source: 190

No CentOS builds as there was no centos/ppc64le image available.

Summary

Non-x86 support looks quite nice. There are some images which can not be built as they rely on external repositories so no aarch64 nor ppc64le packages to use.

Debian ‘stretch’ support is not perfect yet but it is something which I plan to maintain so situation will be going to improve. Note that most of my work will go into ‘source’ type of builds as we want to have same images for both Debian and CentOS systems.