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

[Fam Zheng <famz@redhat.com>]

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?

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

Thanks,

Fam