alpine-rpigpio

Legacy Image

This image still uses the old-style format for Dockerfiles/makefile recipes, that may (or may not) be compatible with the newer image sources. The container should keep working as expected, but for building new images, a significant part of the code needs to be updated.

Container for Alpine Linux + S6 + Python3 + RPi.GPIO

This image serves as the base image for applications / services running on Raspberrpi Pi(s) that require GPIO access, using RPi.GPIO or serial access using PySerial, on Python3 and Pip to manage dependencies.

Based on Alpine Linux from the python3 image with the packages pyserial and RPi.GPIO and wiringpi installed in it.

Get the Image¶

Pull the image for your architecture if it's already available from Docker Hub.

docker pull woahbase/alpine-rpigpio

Image Tags

The image is tagged respectively for the following architectures,

latest tag is retagged from x86_64, so pulling without any tag fetches you that image. For any other architectures specify the tag for that architecture. e.g. for armv8 or aarch64 host it is alpine-rpigpio:aarch64.

non-x86_64 builds have embedded binfmt_misc support and contain the qemu-user-static binary that allows for running it also inside an x86_64 environment that has support for it.

Run¶

Run bash in the container to get a shell.

docker run --rm -it \
  --name docker_rpigpio \
  --device /dev/gpiomem \
  --cap-add SYS_RAWIO \
  --device /dev/ttyAMA0:/dev/ttyAMA0 \
woahbase/alpine-rpigpio \
  /bin/bash

Multi-Arch Support

If you want to run images for other architectures on a x86_64 machine, you will need to have binfmt support configured for your machine before running the image. multiarch, has made it easy for us containing that into a docker container, just run

docker run --rm --privileged multiarch/qemu-user-static --reset -p yes

Now images built for other architectures will also be executable. This is optional though, without the above, you can still run the image that is made for your architecture.

Configuration¶

Although --privileged is not usually required (unless your usecase demands it) for this image, you will still need to pass

--device /dev/gpiochip0 (previously /dev/gpiomem), and --cap-add SYS_RAWIO to access the gpio.
--device /dev/ttyAMA0:/dev/ttyAMA0 for serial access.

Build Your Own¶

Feel free to clone (or fork) the repository and customize it for your own usage, build the image for yourself on your own systems, and optionally, push it to your own public (or private) repository.

Here's how...

Setting up¶

Before we clone the /repository, we must have Git, GNU make, and Docker (optionally, with buildx plugin for multi-platform images) setup on the machine. Also, for multi-platform annotations, we might require enabling experimental features of Docker.

Clone the repo with,

git clone https://github.com/woahbase/alpine-rpigpio
cd alpine-rpigpio

Always Check Before You Make!

Did you know, we could check what any make target is going to execute before we actually run them, with

make -n <targetname> <optional args>

Build and Test¶

To create the image for your architecture, run the build and test target with

make build test

For building an image that targets another architecture, it is required to specify the ARCH parameter when building. e.g.

aarch64armhfarmv7l

make build test ARCH=aarch64

make build test ARCH=armhf

make build test ARCH=armv7l

Make to Run¶

Running the image creates a container and either starts a service (for service images) or provides a shell (can be either a root-shell or usershell) to execute commands in, depending on the image. We can run the image with

make run

But if we just need a root-shell in the container without any fance pre-tasks (e.g. for debug or to test something bespoke), we can run bash in the container with --entrypoint /bin/bash. This is wrapped in the makefile as

make shell

Nothing vs All vs Run vs Shell

By default, if make is run without any arguments, it calls the target all. In our case this is usually mapped to the target run (which in turn may be mapped to shell).

There may be more such targets defined as per the usage of the image. Check the makefile for more information.

Push the Image¶

If the build and test steps finish without any error, and we want to use the image on other machines, it is the next step push the image we built to a container image repository (like /hub), for that, run the push target with

make push

If the built image targets another architecture then it is required to specify the ARCH parameter when pushing. e.g.

aarch64armhfarmv7l

make push ARCH=aarch64

make push ARCH=armhf

make push ARCH=armv7l

That's all folks! Happy containerizing!

Maintenance¶

Sources at Github. Images at Docker Hub.

Maintained (or sometimes a lack thereof?) by WOAHBase.