Reconfigure Raspberry Pi images with an easy, Docker-like configuration file.

pimod overtakes a given Raspberry Pi image by mounting a copy and modifying this copy through QEMU chroot. Therefore one can execute Pi's ARM-code easily on its x86_64 host.

# Create a customized version of the Raspberry Pi OS Lite

FROM 2020-05-27-raspios-buster.img
TO raspbian-buster-upgraded.img

# Increase the image by 100 MB
PUMP 100M

# Enable serial console using built-in configuration tool
RUN raspi-config nonint do_serial 0

# Upgrade the operating system image
RUN apt-get update
RUN bash -c 'DEBIAN_FRONTEND=noninteractive apt-get -y dist-upgrade'

# Install an ssh key from local sources
INSTALL id_rsa.pub /home/pi/.ssh/authorized_keys

For detailed information read our paper.

pimod pimod.sh -h
Usage: pimod.sh [Options] Pifile

Options:
  -c cache  Define cache location.
  -d        Debug on failure; run an interactive shell before tear down
  -t        Trace each executed command for debugging.
  -h        Print this help message.

sudo apt-get install binfmt-support file kpartx lsof p7zip-full parted qemu qemu-user-static unzip wget xz-utils

sudo ./pimod.sh Pifile

# build the docker container
docker build -t pimod .

# run the container privileged to allow loop device usage or…
docker run --rm --privileged -v $PWD:/pimod pimod pimod.sh examples/RPi-OpenWRT.Pifile

# …alternatively use docker-compose
docker-compose run pimod pimod.sh examples/RPi-OpenWRT.Pifile

name: tests
on: push

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v1
        with:
          submodules: recursive
      - name: Run pimod OpenWRT example
        uses: Natur40/pimod@master
        with:
          pifile: examples/RPi-OpenWRT.Pifile

The Pifile contains commands to modify the image.

However, the Pifile itself is just a Bash script and the commands are functions, which are loaded in different stages.

$ cat Upgrade.Pifile
FROM 2018-11-13-raspbian-stretch-lite.img

PUMP 100M

RUN raspi-config nonint do_serial 0

RUN apt-get update
RUN bash -c 'DEBIAN_FRONTEND=noninteractive apt-get -y dist-upgrade'
RUN apt-get install -y sl


# The Upgrade.Pifile will create, called by the following command, a new
# Upgrade.img image based on the given Raspbian image. This image's size is
# increased about 100MB, has an enabled UART/serial output, the latest software
# and sl installed.
$ sudo ./pimod.sh Upgrade.Pifile

# Write the new image to a SD card present at /dev/sdc.
$ dd if=Upgrade.img of=/dev/sdc bs=4M status=progress

FROM sets the SOURCE_IMG variable to a target. This might be a local file or a remote URL, which will be downloaded. This file will become the base for the new image.

By default, the Raspberry Pi's default partition number 2 will be used, but can be altered for other targets.

TO sets the DEST_IMG variable to the given file. This file will contain the new image. Existing files will be overridden.

Instead of calling TO, the Pifile's filename can also indicate the output file, if the Pifile ends with ".Pifile". The part before this suffix will be the new DEST_IMG.

If neither TO is called nor the Pifile indicates the output, DEST_IMG will default to rpi.img in the source file's directory.

INPLACE does not create a copy of the image, but performs all further operations on the given image. This is an alternative to FROM and TO.

INCLUDE includes the provided Pifile in the current one for modularity and re-use. The included file has to have a .Pifile extension which need not be specified.

PUMP increases the image's size about the given amount (suffixes K, M, G are allowed).

INSTALL installs a given file or directory into the destination in the image. The optionally permission mode (chmod) can be set as the first parameter.

PATH adds the given path to an overlaying PATH variable, used within the RUN command.

RUN executes a command in the chrooted image based on QEMU user emulation.

Caveat: because the Pifile is just a Bash script, pipes do not work as one might suspect. A possible workaround could be the usage of bash -c:

RUN bash -c 'hexdump /dev/urandom | head'

HOST executed a command on the local host and can be used to prepare files, cross-compile software, etc.

Because the Pifile is just a Bash script, some dirty brilliant hacks and extensions are possible.

Here documents can be used with the RUN command.

RUN <<EOF
apt-get update
DEBIAN_FRONTEND=noninteractive apt-get -y dist-upgrade
apt-get install -y sl
EOF

Here documents can also be used to create files inside of the guest system, e.g., by using tee or dd.

RUN tee /bin/example.sh <<EOF
#!/bin/sh

echo "Example output."
EOF

If you happen to use pimod in a scientific project, we would very much appreciate if you cited our scientific paper:

@inproceedings{hoechst2020pimod,
  author = {{Höchst}, Jonas and Penning, Alvar and Lampe, Patrick and Freisleben, Bernd},
  title = {{PIMOD: A Tool for Configuring Single-Board Computer Operating System Images}},
  booktitle = {{2020 IEEE Global Humanitarian Technology Conference (GHTC 2020)}},
  address = {Seattle, USA},
  days = {29},
  month = oct,
  year = {2020},
  keywords = {Single-Board Computer; Operating System Image; System Provisioning},
}

• Debian Wiki, qemu-user-static
• raspberry-pi-chroot-armv7-qemu.md
• chroot-to-pi.sh
• PiShrink
• pi-bootstrap