Using Dev Containers to Standardise Development Environments

After running my own homelab for a while, I’ve become pretty familiar with using containers - mostly via Docker, though I may have to make the switch to podman after a recent announcement. One thing I wasn’t aware of was the ability to run containers for the specific purpose of creating a development environment.

Configuring a Dev Container

I first came across this feature in Visual Studio Code (I try to avoid it, but sometimes its a necessary evil :P), there is a lot of great documentation which covers the topic in far more detail than I plan to.

The pre-requisites for setting up a Dev Container are Visual Studio Code (VSCode) and the Dev Containers plugin.

The basic idea is that you create a Dockerfile or docker-compose file, which sets up a container, you can then specify a devcontainer.json file which lets you configure additional settings unique to VSCode e.g. plugins that you want installed inside of the container, and/or VSCode settings you want active whilst in the container.

VSCode will even walk you through the process of creating the container itself if you don’t have a Dockerfile already on hand: Ctrl + Shift + P -> Dev Containers: New Dev Container... will get you started.

Follow this link for a list of all the options available when configuring devcontainer.json.

Here is an example of a quick setup I configured:

{
  "name": "Python 3",
  // Base image provided by Microsoft or use a Dockerfile or Docker Compose file. More info: https://containers.dev/guide/dockerfile
  "image": "mcr.microsoft.com/devcontainers/python:0-3.9",
  // Install pre-configured features into the container - in this case the fish shell
  "features": {
    "ghcr.io/meaningful-ooo/devcontainer-features/fish:1": {
      "fisher": true
    }
  },
  // Specify extensions which should be made available inside of the container
  "customizations": {
    "vscode": {
      "extensions": [
        "vscodevim.vim",
        "ms-python.python",
        "ms-python.pylance",
        "ms-python.black",
        "ms-python.flake8",
        "ms-python.isort"
      ],
      "settings": {
        "python.linting.flake8Enabled": true,
        "python.linting.flake8Path": "/usr/local/bin/flake8",
        "python.formatting.blackPath": "/usr/local/bin/black"
      }
    }
  }
}

Adding Dotfiles

One feature which I thought was really handy is the ability to specify a repository containing dotfiles (linux personalised configuration settings, such as my dwm dotfiles), which can be cloned and configured once the Dev Container is up and running.

This means you can create a Dev Contianer and share it across a team, so that everyone has a standardised development environment. Then you can add your own configuration after the container has been started by using the dotfiles functionality - no one is subjected to your strange configuration (e.g. running the vim extension).

Use of Dev Containers in Neovim

Naturally the first thing I did after discovering this feature in VSCode was to explore whether it is also available in Neovim (my editor of choice) - sure enough I found a plugin. I need to play around with this more to get it configured, but I’m glad to know the option is there.