Docker Development Workflow Setup

As I write code in a lot of different languages using a lot of different frameworks, it makes sense for me to virtualise my development environments in such a way that they’re given their own isolated space so that they can’t infect each other. In today’s post, I’m going to walkthrough my development environment setup using Docker.

Setting up a Clojure environment

The example that I’ll use is the development container that I have setup for Clojure. First of all, I create a workspace for my Clojure development on my host machine, under my source directory like anything else. I’ll put this in ~/src/clojure.

In that folder, I create two scripts. run.sh which just gets a disposable container up and running and Dockerfile which is based off of the clojure:latest image from the docker hub repository, but just adds a couple of extra bits and pieces to help the development environment get started.

Dockerfile

The Dockerfile is pretty straight forward but relies on some magic. Unfortunately, here’s my solution loses its portability. DOH! But, I’m still unsure of how to get around this. To keep permissions and ownerships common between the host and the container (because we’ll be mounting a volume from the host), I create my developer account called michael as the next account after root. This is how it is on my host machine, so there’s no conflicting user/group ids.

FROM clojure:latest

RUN apt-get update && \
    apt-get install -y sudo && \
    apt-get clean && \
    rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

RUN adduser --disabled-password --gecos '' michael && \
    adduser michael sudo && \
    echo '%sudo ALL=(ALL) NOPASSWD:ALL' >> /etc/sudoers

WORKDIR /home/michael
ENV HOME /home/michael
VOLUME ["/home/michael"]

USER michael

A couple of small things to note.

After installing sudo, I clean up any dead weight that apt-get may have left behind. This is just container maintenance to ensure that the image that’s generated is as small as possible.

We add the michael account with no password and directly into the sudo group. We also adjust the sudo config so that users in the sudo group can issue administrative commands without needing to supply a password.

From there, it’s all about making the home directory of michael centre stage for the container and switching to the michael user.

run.sh

The run script is fairly straight forward. All we need it to do is mount our current directory as a volume in the container and start bash. Of course, if you need to publish ports or create other volume mounts; here is where you’d do it.

#!/bin/bash

docker run -ti --rm -v $(pwd):/home/michael clojure:latest /bin/bash

Start developing

You’re done now. Everything creates in context of your non-root user. Your tools are available to you in your container and you’re free to develop using your editor on your host.