Nerves development environment with Docker (and VS Code)

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How do you feel that you can acquire the development environment for Nerves without affecting the host environment?:thinking: The Docker can do it with minimal steps!!:tada::tada::tada:

We want to offer the Docker solution mainly for beginners and Windows users.

Dockerfile:
https://github.com/NervesJP/docker-nerves

Docker Hub (pre-built image)

VS Code dev-container:
https://github.com/NervesJP/nerves-devcontainer

Main contributions and use cases

  • If you are new to Nerves, you can easily try out its development without any affect on your host PC.
  • It will be convenient for hands-on training to provide a unified environment for all participants.
  • Even if you are already using Nerves, you can quickly try out the latest development environment. Docker does not affect your host environment.
  • The Docker Hub repository here publishes the pre-built image. You can try it right away by just pulling it (but it may not always be up to date).
  • You can also experience a better development environment by using the Visual Studio Code and its extension.

How to use with Docker alone

You need to install Docker Desktop
Docker has some requirements for host PC to be operated. See details: Windows / macOS

from Docker Hub repository

You can try the Nerves development with pre-built image.

$ docker pull nervesjp/nerves
$ docker run -it -w /workspace nervesjp/nerves
root@6e304327bd2e:/workspace#

from GitHub repository

You can build Docker image locally, and customize it to your needs.

$ git clone https://github.com/NervesJP/docker-nerves
$ cd docker-nerves

$ docker build -t docker-nerves .
$ docker run -it -w /workspace docker-nerves 
root@9bc88d0fc7b8:/workspace# pwd
/workspace
root@9bc88d0fc7b8:/workspace# echo ${HOME}
/root
root@9bc88d0fc7b8:/workspace# ls ~/.mix/*
/root/.mix/rebar  /root/.mix/rebar3

/root/.mix/archives:
hex-0.20.6  nerves_bootstrap-1.10.0

Tips: Mount volumes on host

Since a filesystem into Docker image will disappear when an image rebuild/execute, it is useful to mount a volume on host to keep files of Nerves project. -v ${PWD}:/workspace can mount current directory on host to Docker image.

$ docker run -it -w /workspace -v ${PWD}:/workspace docker-nerves

It is also efficient to mount Nerves related setting files, such as ~/.ssh/ and ~/.nerves. Following is an example to share setting files between host and image.

$ docker run -it -w /workspace -v ${PWD}:/workspace  -v ~/.ssh:/root/.ssh -v ~/.nerves:/root/.nerves docker-nerves

More convenient with VS Code

Visual Studio Code is one of the most popular editor for engineers.
Remote - Containers extensions provides an awesome experience with Docker development containers.

See details:

How to use

  1. Clone the repository
git clone https://github.com/NervesJP/nerves-devcontainer

  1. Start VS Code, run the Remote-Containers: Open Folder in Container… command from the Command Palette (F1) or quick actions Status bar item, and select the project folder you cloned at Step 1.

  2. After a while, you can enjoy Nerves/Elixir development with Bash on Docker image and VS Code like as follows.

root@ebc5e1a19ae3:/workspaces/nerves-devcontainer# ls 
LICENSE.txt  README.md
root@ebc5e1a19ae3:/workspaces/nerves-devcontainer# ls ~/.mix/*
/root/.mix/rebar  /root/.mix/rebar3

/root/.mix/archives:
hex-0.20.6  nerves_bootstrap-1.10.0
root@ebc5e1a19ae3:/workspaces/nerves-devcontainer# elixir --version 
Erlang/OTP 23 [erts-11.1.3] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1] [hipe]

Elixir 1.11.2 (compiled with Erlang/OTP 23)
root@ebc5e1a19ae3:/workspaces/nerves-devcontainer# iex 
Erlang/OTP 23 [erts-11.1.3] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1] [hipe]

Interactive Elixir (1.11.2) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)>
  1. Note that you need to generate your SSH keys, only for the first time to login Docker image.
root@ebc5e1a19ae3:/workspaces/nerves-devcontainer# ssh-keygen -t rsa -N "" -f .ssh/id_rsa`

Tips

Manual build of Docker image locally

This repository will clone pre-built image on Docker Hub.

You can also build Docker image locally by locating above Dockerfile to ./devcontainer and uncommenting //"dockerFile": "Dockerfile", on ./devcontainer/devcontainer.json.
It means you can customize your own Nerves development environment as you want.

Mounted files about Nerves settings

Each time an image is execute, a filesystem into Docker image will disappear. So Nerves related setting directories are mounted in the current (this) directory on the host.

First directory is ${PWD}/.ssh that is expected to contain id_rsa and id_rsa.pub SSH key pairs.
They are used for the construction of Nerves firmware and secure connection to Nerves devices.
It is mounted to ~/.ssh/ on Docker image.
To generate your SSH keys, you need to operate ssh-keygen -t rsa -N "" -f /workspaces/nerves-devcontainer/.ssh/id_rsa after logging into Docker image for the first time.

Second is ${PWD}./nerves that is mounted to ~/.nerves. It keeps archives of Nerves toolchains and nerves_system_br.
If it disappeared when Docker container was restarted, you need to download archives every time you operate mix deps.get.
So we decided to mount it on this directory.
Although mix deps.get at first will take a while to unzip archives to ./nerves/artifacts due to poor performance about bindings between host and container filesystems, we think it is acceptable compared that we always have to wait when running mix deps.get for a long time.

In addition, your Nerves project can be kept on the current directory by the VS Code automatic feature.

Current limitation(s)

burn Nerves firmware to microSD card

Docker has restrict policies to avoid effecting host environment. Therefore, mix burn cannot be operated from Docker image because there is no right to access /dev to on host as a root user.

One way to burn Nerves firmware is just operating fwup on the host. fwup is an utility for constructing/burning Nerves firmware.
https://github.com/fhunleth/fwup

After installing fwup on the host according to this step, please do following command on the host terminal (e.g., PowerShell as Administrator, Terminal.app).

$ cd <your_nerves_project_dir>
$ fwup _build/${MIX_TARGET}_dev/nerves/images/<project_name>.fw

Please let us know if you have a cool solution! (issue)

Any questions, suggestions and comments (including English quality :smile: ) are welcome!!

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