# pimod [![CI: Tests](https://github.com/Nature40/pimod/actions/workflows/tests.yml/badge.svg)](https://github.com/Nature40/pimod/actions/workflows/tests.yml) [![CI: Shellcheck](https://github.com/Nature40/pimod/actions/workflows/shellcheck.yml/badge.svg)](https://github.com/Nature40/pimod/actions/workflows/shellcheck.yml) [![CI: Build and upload DockerHub image](https://github.com/Nature40/pimod/actions/workflows/dockerhub.yml/badge.svg)](https://github.com/Nature40/pimod/actions/workflows/dockerhub.yml) [![Docker Hub: Version](https://img.shields.io/docker/v/nature40/pimod?color=blue&label=Docker%20Hub&logo=docker&logoColor=lightgrey&sort=semver)](https://hub.docker.com/r/nature40/pimod/tags) Reconfigure Raspberry Pi images with an easy, Docker-like configuration file. ## About pimod overtakes a given Raspberry Pi image file by mounting a copy and modifying it within a QEMU chroot. This allows the execution of a Pi's ARM code on whatever target, e.g., a x86\_64 host. To ease the usability, a Docker-inspired recipe, called the Pifile, is used to instrument pimod. ``` # Example Pifile to create a customized version of the Raspberry Pi OS Lite # Based on a remote image, which will be cached locally, create the altered raspi_example.img file FROM https://downloads.raspberrypi.org/raspios_lite_arm64/images/raspios_lite_arm64-2023-02-22/2023-02-21-raspios-bullseye-arm64-lite.img.xz TO rapsi_example.img # Increase the image by 100 MB PUMP 100M # Install an ssh key from local sources RUN mkdir -p /home/pi/.ssh INSTALL id_rsa.pub /home/pi/.ssh/authorized_keys # Enable the serial console and SSH RUN raspi-config nonint do_serial 0 RUN raspi-config nonint do_ssh 0 # Install the important cowsay util RUN apt-get update RUN apt-get install -y cowsay ``` ## Installation, Usage ``` Usage: pimod.sh [Options] Pifile Options: -c --cache DEST Define cache location. -d --debug Debug on failure; run an interactive shell before tear down. -h --help Print this help message. -r --resolv TYPE Specify which /etc/resolv.conf file to use for networking. By default, TYPE "auto" is used, which prefers an already existing resolv.conf, only to be replaced by the host's if missing. TYPE "guest" never mounts the host's file within the guest, even when such a file is absent within the image. TYPE "host" always uses the host's file within the guest. Be aware that when run within Docker, the host's file might be Docker's resolv.conf file. -t --trace Trace each executed command for debugging. ``` ### Docker #### Getting or Building the Docker Image There are pre-built images available on [Docker Hub](https://hub.docker.com/r/nature40/pimod): ```sh docker pull nature40/pimod ``` Alternatively, you can simply build the image yourself locally. This is essential for development, among other things: ```sh git clone https://github.com/Nature40/pimod.git cd pimod docker build -t nature40/pimod . ``` #### Using the Docker Image Afterwards, the Docker image can either be used by `docker` or `docker compose`: ```sh # Using Docker: docker run --rm --privileged -v $PWD:/pimod nature40/pimod pimod.sh examples/RPi-OpenWRT.Pifile # Using Docker Compose: docker compose run pimod pimod.sh examples/RPi-OpenWRT.Pifile ``` ### Debian Of course, Docker isn't really necessary and pimod can also be used on, e.g., a Debian directly: ```sh sudo apt-get install \ binfmt-support \ exfatprogs \ fdisk \ file \ git \ kpartx \ lsof \ p7zip-full \ qemu-user-static \ rsync \ unzip \ wget \ xz-utils \ units sudo ./pimod.sh Pifile ``` ### GitHub Actions Pimod can also be used as a GitHub Action and is available on the [marketplace](https://github.com/marketplace/actions/run-pimod). ```yml name: tests on: push jobs: build: runs-on: ubuntu-26.04 steps: - name: Checkout repository uses: actions/checkout@v6 with: submodules: recursive - name: Run pimod OpenWRT example uses: Nature40/pimod@HEAD with: pifile: examples/RPi-OpenWRT.Pifile ``` ## Pifile The Pifile contains commands to modify the image. Those commands are grouped in stages which pimod executes in their corresponding order. - First, all _setup stage_ commands are being executed to download the base image and configure the output. - The _prepare stage_ follows which pre-flight commands, e.g., resizing the output image. - The action happens in the _chroot stage_ where the QEMU chroot is built, commands are executed within, files are copied and so on. - The _postprocess stage_ might clean up some things while the chroot is still active. - Finally, the _finalize stage_ runs after teardown for image-level operations such as `SHRINK`. However, as the Pifile being just a Bash script by itself and the commands are functions, which are loaded in different stages, Bash scripting is possible within the Pifile to some extend. More internals are documented in our [our scientific paper](https://jonashoechst.de/assets/papers/hoechst2020pimod.pdf). If you stumble upon details there that you think belong in this README, feel free to create an issue or pull request. ### Example ``` $ 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 ``` Further and more expressive examples are available in this repository's `./examples` directory. Please take a look and feel free to submit your own examples if they are covering a current blind spot. ### Commands #### Stage independent ##### `INCLUDE PATH_TO_PIFILE`, `INCLUDE URL` `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. `INCLUDE` can also accept URLs to remote Pifiles, such as raw GitHub URLs, allowing you to use public modules directly. Remote Pifiles are cached locally (see `--cache` option) and will be reused on subsequent runs. ``` # Include a local module INCLUDE modules/setup # Include a remote module from GitHub (omits Pifile extension) INCLUDE https://raw.githubusercontent.com/user/repo/main/modules/module ``` #### 1. Setup Stage ##### `FROM PATH_TO_IMAGE [PARTITION_NO]`, `FROM URL [PARTITION_NO]` `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 PATH_TO_IMAGE` `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 FROM_ARGS...` `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`. #### 2. Prepare Stage ##### `PUMP SIZE` `PUMP` increases the image's size about the given amount (suffixes K, M, G are allowed). ##### `ADDPART SIZE PTYPE FS` `PUMP` appends a partition of the size (suffixes K, M, G are allowed) using a partion type and file system (ext4, exfat, ...). #### 3. Chroot Stage ##### `INSTALL SOURCE DEST` `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. ##### `EXTRACT SOURCE DEST` `EXTRACT` copies a given file or directory from the image to the destination. ##### `PATH /my/guest/path` `PATH` adds the given path to an overlaying PATH variable, used within the `RUN` command. ##### `WORKDIR /my/guest/path` `WORKDIR` sets the working directory within the image. ##### `ENV KEY [VALUE]` `ENV` either sets or unsets an environment variable to be used within the image. If two parameters are given, the first is the key and the second the value. If one parameter is given, the environment variable will be removed. An environment variable can be either used via `$VAR` within another sub-shell (`sh -c 'echo $VAR'`) or substituted beforehand via `@@VAR@@`. ``` ENV FOO BAR RUN sh -c 'echo FOO = $FOO' # FOO = BAR - substituted within a sh in the image RUN echo FOO = @@FOO@@ # FOO = BAR - substituted beforehand via pimod ENV FOO ``` ##### `RUN CMD [PARAMS...]` `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 CMD [PARAMS...]` `HOST` executed a command on the local host and can be used to prepare files, cross-compile software, etc. #### 4. Postprocess Stage ##### `ZERO` `ZERO` fills unused space in the filesystem with zeros. This allows for better compression of the resulting image, resulting in smaller image files. Useful when creating images for distribution. #### 5. Finalize Stage ##### `SHRINK [SIZE]` `SHRINK` reduces the image file size by shrinking the filesystem and partition. The operation performs a filesystem check, resizes the filesystem, updates the partition table, and truncates the image file. **Without SIZE parameter**: Shrinks to the minimum filesystem size plus a 5% safety buffer to prevent the filesystem from being 100% full. **With SIZE parameter**: Shrinks the image to the exact target size (suffixes K, M, G are allowed). The target size must be large enough to contain the minimum required filesystem size plus partition overhead. If the current image is already smaller than the target size, no action is taken. Examples: ```sh SHRINK # Shrink to minimum size + 5% buffer SHRINK 2G # Shrink to exactly 2GB (if possible) SHRINK 500M # Shrink to exactly 500MB (if possible) ``` Note: `SHRINK` cannot be used with block devices, only image files. ### Pifile Extensions Because the *Pifile* is just a Bash script, some ~~dirty~~ brilliant hacks and extensions are possible. #### Bulk execution Sub shells can be used with the `RUN` command. ```sh RUN sh -c ' apt-get update DEBIAN_FRONTEND=noninteractive apt-get -y dist-upgrade apt-get install -y sl ' ``` #### Inplace Files Here documents can also be used to create files inside of the guest system, e.g., by using `tee` or `dd`. ```bash RUN tee /bin/example.sh <