Testing OpenStack using tempest: all is packaged, try it yourself

tl;dr: this post explains how the new openstack-tempest-ci-live-booter package configures a machine to PXE boot a Debian Live system running on KVM in order to run functional testing of OpenStack. It may be of interest to you if you want to learn how to PXE boot a KVM virtual machine running Debian Live, even if you aren’t interested in OpenStack.

Moving my CI from one location to another leads to package it fully

After packaging a release of OpenStack, it’s kind of mandatory to functionally test the set of packages. This is done by running the tempest test suite on an already deployed OpenStack installation. I used to do that on a real hardware, provided by my employer. But since I’ve lost my job (I’m still looking for a new employer at this time), I also lost access to the hardware they were providing to me.

As a consequence, I searched for a sponsor to provide the hardware to run tempest on. I first sent a mail to the openstack-dev list, asking for such a hardware. Then Rochelle Grober and Stephen Li from Huawei got me in touch with Zachary Smith, the CEO of Packet.net. And packet.net gave me an account on their system. I am amazed how good their service is. They provide baremetal servers around the world (15 data centers), provisioned using an API (meaning, fully automatically). A big thanks to them!

Anyway, even if I planned for a few weeks to give a big thanks to the above people (they really deserves it!), this isn’t the only goal of this post. This is to introduce how to run your own tempest CI on your own machine. Because since I have been in the situation where my CI had to move twice, I decided to industrialize it, and fully automate the setup of the CI server. And what does a DD do when writing software? Package it of course. So I packaged it all, and uploaded it to the archive. Here’s how to use all of this.

General principle

The best way to run an OpenStack tempest CI is to run it on a Debian Live system. Why? Because setting-up a full OpenStack environment takes a lot of time, mostly spent on disk I/O. And on a live system, everything runs on a RAM disk, so installing under this environment is the fastest way one could do. This is what I did when working with Mirantis: I had a real baremetal server, which I was PXE booting on a Debian Live system. However nice, this imposes having access to 2 servers: one for running the Live system, and one running the dhcp/pxe/tftp server. Also, this means the boot server needs 2 nics, one on the internet, and one for booting the 2nd server that will run the Live system. It was not possible to have such specific setup at packet, so I decided to replicate this using KVM, so it would become portable. And since the servers at packet.net are very fast, it isn’t much of an issue anymore to not run on baremetal.

Anyway, let’s dive into setting-up all of this.

Network topology

We’ll assume that one of your interface has internet access, let’s say eth0. Since we don’t want to destroy any of your network config, the openstack-tempest-ci-live-booter package will use a dummy network interface (ie: modprobe dummy) and bridge it to the network interface of the KVM virtual machine. That dummy network interface will be configured with 192.168.100.1, and the Debian Live KVM will use 192.168.100.2. This convenient default can be changed, but then you’ll have to pass your specific network configuration to each and every script (just read the beginning of each script to read the parameters).

Configure the host machine

First install the openstack-tempest-ci-live-booter package. This runtime depends on the isc-dhcp-server, tftpd-hpa, apache2, qemu-kvm and all what’s needed to run a Debian Live machine, booting it over PXE / iPXE (the package support both, more on iPXE later). So, let’s do it:

apt-get install openstack-tempest-ci-live-booter

The package, once installed, doesn’t do much. To respect the Debian policy, it can’t touch configuration files of other packages in maintainer scripts. Therefore, you have to manually run:

openstack-tempest-ci-live-booter-config --configure-dummy-nick

Running this script will:

  • configure the kvm-intel module to allow nested visualization (by unloading the module, adding “options kvm-intel nested=y” to /etc/modprobe.d, and reloading the module)
  • modprobe the dummy kernel module, run “ip link set name tempestnic0 dev dummy0” to create a tempestnic0 dummy interface
  • create a tempestbr bridge, set 192.168.100.1 for the bridge IP, bridge the tempestnic0 and tempesttap
  • configure tftpd-hpa to listen on 192.168.100.1
  • configure isc-dhcp-server to dhcpreply 192.168.100.2 on the tempestbr, so that the KVM machine can boot up with an IP
  • configure apache2 to serve the filesystem.squashfs root filesystem, loaded by the Linux kernel at boot time. Note that you may need to manually start and/or reload apache after this setup though.

Again, you can change the IP addresses if you like. You can also use a real interface if you intend to boot a real hardware rather than a KVM machine (in which case, just omit the –configure-dummy-nick, and manually configure your 2nd interface).

Also, openstack-tempest-ci-live-booter provides a /etc/init.d/openstack-tempest-ci-live-booter script which will configure NAT on your server, so that the Debian Live machine has internet access (needed for apt-get operations). Edit the file if you need to change 192.168.100.1/24 by something else. The script will pick-up the interface that is connected to the default gateway by itself.

The dhcp server is configured to support both legacy PXE and the new iPXE standard. I had to support iPXE, because that’s what the standard KVM ROM does, and also I wanted to keep legacy support for older baremetal hardware. The way iPXE works is that dhcpd tells the client where to fetch the iPXE script, which itself chains to lpxelinux.0 (instead of the standard pxelinux.0). It’s rather easy to setup once you understood how it works.

Build the live image

Now that the PXE server is configured, it’s now time to build the Debian live image. Simply do this to build the image, and copy its resulting files in the PXE server folder (ie: /var/lib/tempest-live-booter):

mkdir live
cd live
openstack-tempest-ci-build-live-image --debian-mirror-addr http://ftp.nl.debian.org/debian

Since we need to login in that server later on, the script will create an ssh key-pair. If you want your own keys, simply drop the id_rsa and id_rsa.pub files in your current folder before running the script. Then make it so that this key-pair can be later on used by default by the user who will run the tempest script (ie: copy id_rsa and id_rsa.pub in the ~/.ssh folder).

Running the openstack-tempest-ci

What the openstack-tempest-ci script does is (re-)starting your KVM virtual machine, ssh into it, upgrade it to sid, install OpenStack, and eventually run all the tempest suite. There’s 2 ways to run it: either install the openstack-tempest-ci package, eventually configure it (in /etc/default/openstack-tempest-ci), and simply run the “openstack-tempest-ci” command. Or, you can skip the installation of the package, and simply run it from source:

git clone http://anonscm.debian.org/git/openstack/debian/openstack-meta-packages.git
cd openstack-meta-packages/src
./openstack-tempest-ci

Indeed, the script is designed to copy all scripts from source inside the Debian Live machine before using these scripts. The reason it’s doing that is because we want to avoid the situation where a modification needs to be uploaded to Debian before being able to test it, and also it was needed to be able to run the openstack-tempest-ci script without installing a package (which would need root access that I don’t have on casulana.debian.org, where running tempest is needed to test official OpenStack Debian images). So, definitively, feel free to hack everything in openstack-meta-packages/src before running the tempest script. Also, openstack-tempest-ci will look for a sources.list file in the current directory, and upload it to the Debian Live system before doing the upgrade/install. This way, it is easy to use the closest mirror.

Post a Comment

You must be logged in to post a comment.