Building in Docker (Debian stretch) fails: Module loop not found

[marians]

What were you doing?

I am trying to run the build process on my Mac in Docker, using debian:stretch as a base image.

If somebody has that working, I'd appreciate your help.

My Dockerfile so far:

FROM debian:stretch

WORKDIR /

RUN apt-get update -y
RUN apt-get install -y realpath p7zip-full qemu-user-static git wget kmod

RUN git clone https://github.com/guysoft/CustomPiOS.git
RUN git clone https://github.com/guysoft/FullPageOS.git

WORKDIR /FullPageOS/src/image

RUN wget -c --trust-server-names 'https://downloads.raspberrypi.org/raspbian_lite_latest'

WORKDIR /FullPageOS/src

RUN /CustomPiOS/src/update-custompios-paths

RUN modprobe loop

CMD ["bash", "-x", "./build_dist"]

What did you expect to happen?

I expected to be able to execute docker build to have a Docker image that I could use for building a FullPageOS image.

What happened instead?

docker build exited unsuccessfully with this error:

Step 12/13 : RUN modprobe loop
---> Running in 6090cf643b63
modprobe: ERROR: ../libkmod/libkmod.c:586 kmod_search_moddep() could not open
  moddep file '/lib/modules/4.9.60-linuxkit-aufs/modules.dep.bin'
modprobe: FATAL: Module loop not found in directory /lib/modules/4.9.60-linuxkit-aufs

Version of FullPageOS?

Current default branch, which is devel it seems.

[guysoft]

Not a docker expert, looks like the system does not support loopback devices. Its failing on the modprobe loop command, which is a kernel module, that image is missing it. Quick googeling returns this. They mention a switch there to make the container support loopback devices.

I never got docker to work (again, not an expert), but there is a vagrant script available and documented.

If you do get a docker method to work would love to add it to CustomPiOS.

[marians]

Thanks @guysoft for the quick reply! That link helped me out actually. I had to remove the modprobe command from the Dockerfile, as it would only work at runtime (docker run).

I got it working like this:

Dockerfile

FROM debian:stretch

WORKDIR /

RUN apt-get update -y
RUN apt-get install -y realpath p7zip-full qemu-user-static git wget kmod sudo python3

RUN git clone https://github.com/guysoft/CustomPiOS.git
RUN git clone https://github.com/guysoft/FullPageOS.git

WORKDIR /FullPageOS/src/image

RUN wget -c --trust-server-names 'https://downloads.raspberrypi.org/raspbian_lite_latest'

WORKDIR /FullPageOS/src

RUN /CustomPiOS/src/update-custompios-paths

WORKDIR /

ADD entrypoint.sh /entrypoint.sh
RUN chmod +x /entrypoint.sh

ENTRYPOINT ["/entrypoint.sh"]

entrypoint.sh

#!/bin/bash

modprobe loop

cd /FullPageOS/src

bash -x ./build_dist

Execution

docker build -t fullpageos .
docker run -ti --privileged=true fullpageos

So I guess all I have to do now is make sure the resulting image file is written to a volume instead of into the container. And I'll probably pass a few FULLPAGEOS_* environment variables for customization. Sweet!

[guysoft]

Take a look at the vagrant folder. If you can PR a docker folder that works for you, I can populate it to all CustomPiOS distros