Re: [Qemu-devel] [PATCH RFC v4 4/4] docker: Add debootstrap-arm image

["Alex Bennée" <alex.bennee@linaro.org>]

Fam Zheng <famz@redhat.com> writes:

> On Mon, 07/11 20:06, Alex Bennée wrote:
>>
>> Fam Zheng <famz@redhat.com> writes:
>>
>> > Signed-off-by: Fam Zheng <famz@redhat.com>
>> > ---
>> >  tests/docker/dockerfiles/debootstrap-arm.docker | 35 +++++++++++++++++++++++++
>> >  1 file changed, 35 insertions(+)
>> >  create mode 100644 tests/docker/dockerfiles/debootstrap-arm.docker
>> >
>> > diff --git a/tests/docker/dockerfiles/debootstrap-arm.docker b/tests/docker/dockerfiles/debootstrap-arm.docker
>> > new file mode 100644
>> > index 0000000..cb15f2f
>> > --- /dev/null
>> > +++ b/tests/docker/dockerfiles/debootstrap-arm.docker
>> > @@ -0,0 +1,35 @@
>> > +FROM debian:testing
>> > +
>> > +RUN apt-get update
>> > +RUN apt-get install -y fakeroot debootstrap qemu-user-static
>> > +
>> > +RUN mkdir /debootstrap-arm
>> > +
>> > +RUN cd /debootstrap-arm && fakeroot debootstrap --variant=buildd --foreign \
>> > +    --arch=armhf testing . http://httpredir.debian.org/debian
>> > +
>> > +RUN sed -i 's/in_target mount/echo not for docker in_target mount/g' \
>> > +    /debootstrap-arm/debootstrap/functions
>> > +
>> > +RUN mkdir -p /debootstrap-arm/usr/local/bin
>> > +
>> > +RUN ln /usr/bin/qemu-arm-static /debootstrap-arm/usr/bin/qemu-arm && \
>> > +    ln /usr/bin/qemu-arm-static /debootstrap-arm/usr/bin/qemu-arm-static && \
>> > +    ln /usr/bin/qemu-arm-static /debootstrap-arm/usr/local/bin/qemu-arm && \
>> > +    ln /usr/bin/qemu-arm-static /debootstrap-arm/usr/local/bin/qemu-arm-static
>> > +
>> > +# Run stage 2
>> > +RUN if ! chroot /debootstrap-arm /debootstrap/debootstrap --second-stage; then \
>> > +        echo "Failed to chroot and do stage 2"; \
>> > +        echo "Please set up binfmt_misc to point arm binary to one of:"; \
>> > +        echo "  /usr/bin/qemu-arm"; \
>> > +        echo "  /usr/bin/qemu-arm-static"; \
>> > +        echo "  /usr/local/bin/qemu-arm"; \
>> > +        echo "  /usr/local/bin/qemu-arm-static"; \
>> > +        exit 1; \
>> > +    fi
>> > +RUN chroot /debootstrap-arm sh -c 'cat /etc/apt/sources.list | sed "s/deb/deb-src/" >> /etc/apt/sources.list'
>> > +RUN chroot /debootstrap-arm apt-get update
>> > +RUN chroot /debootstrap-arm apt-get build-dep -y qemu
>> > +RUN chroot /debootstrap-arm apt-get install -y ccache
>> > +ENV QEMU_CHROOT /debootstrap-arm
>>
>> OK I've done some more experimenting and two things are apparent:
>>
>>   debootstrap is widely packaged for various distros
>>
>> And
>>
>>   The script it fairly portable so we can always run it directly
>>
>> I hacked up the .pre script to do the following and tested on my Arch
>> VM:
>>
>> #!/bin/sh
>> #
>> # Simple wrapper for debootstrap, run in the docker build context
>> #
>> FAKEROOT=`which fakeroot 2> /dev/null`
>> DEBOOTSTRAP=`which debootstrap 2> /dev/null`
>> DEBOOTSTRAP_SOURCE=https://anonscm.debian.org/git/d-i/debootstrap.git
>>
>> if [ -z $FAKEROOT ]; then
>>     echo "Please install fakeroot to enable bootstraping"
>>     exit 1
>> fi
>>
>> if [ -z $DEBOOTSTRAP ]; then
>>     echo "No debootstrap installed, attempting to install from SCM"
>>     git clone ${DEBOOTSTRAP_SOURCE} ./debootstrap.git
>>     export DEBOOTSTRAP_DIR=./debootstrap.git
>>     DEBOOTSTRAP=./debootstrap.git/debootstrap
>> fi
>>
>> echo "Building a rootfs using ${FAKEROOT} and ${DEBOOTSTRAP}"
>>
>> ${FAKEROOT} /bin/sh -x ${DEBOOTSTRAP} --variant=buildd --foreign --arch=$DEB_ARCH $DEB_TYPE . http://httpredir.debian.org/debian
>> exit 0
>>
>> So I think it is feasible to but the pre-requisite checking and work
>> around in the pre script and be done with it. It seems neater than the
>> chroot within a container approach.
>>
>> Thoughts?
>
> Yes, makes sense to me.  Two more questions:
>
> Can we have "make docker-images" to update the docker image if pre script has
> been updated?

We could, I'm not sure what the dependency should be for a file that may
or may not exist?

The larger problem is what to do about the fact that debootstrap is a
multi-arch script? Currently I can manually build the
qmu:debian-bootstrap image from the command line for any linux-user
architecture.

Once this is done I can then run all the tests under that single
emulated architecture. The question is should the "make docker" expand
debian-bootstrap into all the various architecture targets and build
them all or just assume what ever one is set-up by the user is the one
that gets tested?

Currently:

  make docker-image-debian-bootstrap DEB_ARCH=arm64 DEB_TYPE=testing V=1 J=9

Will fail because the build machinery doesn't know what
--include-executable to pass to the docker.py script.

However after that everything should work.

My current state is at:

   https://github.com/stsquad/qemu/tree/misc/docker-linux-user-v4

I'll post v5 shortly after I've done some basic testing.

>
> Can we skip debootstrap (i.e. skip .pre script) if it's only the dockerfile
> that has changed?

No, because a running a dockerfile implies re-building the container
from scratch and the .pre script needs to pre-seed the build context.

>
> Thanks,
>
> Fam


--
Alex Bennée