xen/automation/build

Docker Containers

These Docker containers should make it possible to build Xen in any of the available environments on any system that supports running Docker. They are organized by distro and tagged with the version of that distro. They are available from the GitLab Container Registry under the Xen project at the registry and can be pulled with Docker from the following path:

docker pull registry.gitlab.com/xen-project/xen/DISTRO:VERSION

To see the list of available containers run make in this directory. You will have to replace the / with a : to use them.

Building Xen

From the top level of the source tree it should be possible to run the following:

./automation/scripts/containerize make

Which will cause the top level make to execute within the default container, which is currently defined as Debian Stretch. Any arguments specified to the script will be executed within the container from the default shell.

There are several environment variables which the containerize script understands.

• DOCKED_CMD: Whether to use docker or podman for running the containers. podman can be used as a regular user (rootless podman), but for that to work, /etc/subuid and /etc/subgid needs to containe the proper entries, for such user. docker is the default, for running with podman, do:

  DOCKER_CMD=podman ./automation/scripts/containerize make
  

• CONTAINER: This overrides the container to use. For CentOS 7, use:

  CONTAINER=centos7 ./automation/scripts/containerize make
  

• CONTAINER_PATH: This overrides the path that will be available under the /build directory in the container, which is the default path.

  CONTAINER_PATH=/some/other/path ./automation/scripts/containerize ls
  

• CONTAINER_ARGS: Allows you to pass extra arguments to Docker when starting the container.

• CONTAINER_UID0: This specifies whether root is used inside the container.

• CONTAINER_NO_PULL: If set to 1, the script will not pull from docker hub. This is useful when testing container locally.

If your docker host has Linux kernel > 4.11, and you want to use containers that run old glibc (for example, CentOS 6 or SLES11SP4), you may need to add

vsyscall=emulate

to the host kernel command line. That enables a legacy interface that is used by old glibc.

Building a container

There is a makefile to make this process easier. You should be able to run make DISTRO/VERSION to have Docker build the container for you.

Xen's dockerfiles use heredocs, which depend on the standardised dockerfile syntax introduced by [BuiltKit]. This should work by default starting with docker 23.0, or podman/buildah v1.33. For older versions of docker, it can be activated with DOCKER_BUILDKIT=1 in the environment.

If you define the PUSH environment variable when running the former make command, it will push the container to the registry if you have access to do so and have your Docker logged into the registry.

To login you must run docker login registry.gitlab.com. For more information see the registry help.

This example shows how to refresh a container for a rolling release such as openSUSE Tumbleweed. Login with the gitlab.com credentials.

docker login registry.gitlab.com/xen-project/xen
make -C automation/build suse/opensuse-tumbleweed
env CONTAINER_NO_PULL=1 \
  CONTAINER=tumbleweed \
  CONTAINER_ARGS='-e CC=gcc -e CXX=g++ -e debug=y' \
  automation/scripts/containerize automation/scripts/build < /dev/null
make -C automation/build suse/opensuse-tumbleweed PUSH=1

Building/Running container for a different architecture

On a x86 host, it is possible to build and run containers for other arch (like running a container made for Arm) with docker taking care of running the appropriate software to emulate that arch. For this, simply install the package qemu-user-static, and that's it. Then you can start an Arm container on x86 host like you would start an x86 container.

If that doesn't work, you might find some information on multiarch/qemu-user-static.