Dev containers

“Works on my machine”

I worked on a project on and off for a few years. One day, a new colleague joined the project and tried to set it up on his machine. The project is pretty complex to set up, requiring the installation of various software. I thought the readme is very detail and up-to-date, but it turned out it wasn’t. The colleague spent over a day fixing some weird errors that I couldn’t reproduce on my machine. I did the setup a few years back when I onboarded to the project, and it worked, so I never changed the settings again. I hope there is a way to make the setup consistent and easy for everyone.

What is devcontainer?

The Visual Studio Code Remote - Containers extension allows you to use a Docker container as a full-featured development environment. This helps ensure a consistent environment across developer machines and makes it easy for new team members and contributors to get up and running.

Do I have to use vscode?

Yes, I know what you’re thinking, but trust me, once you appreciate the benefits of devcontainers, switching to vscode will be a no-brainer. vscode is the best IDE that supports devcontainers.

System requirements

• Install Docker.
• Install vscode and the “Dev Containers” extension.
• Install the vscode code command.

Demo

I created a GoLang project to demonstrate the use of devcontainers.

• Option 1: Click the “Dev Containers Open” Badge

  • This is a truly one-click spin up! This automatically clones the project to a devcontainer volume and launches it in vscode

• Option 2: Open the project in vscode and open it in devcontainer

  • Manually clone the project to your machine and run code /path/to/project to open the project in vscode. vscode detects the configurations in .devcontainer and prompts you to open the project in the devcontainer:

  

It can be a bit slow to start the container for the first time, but the subsequent start up should be much faster because of caching. Once the devcontainer has started, it already includes all the software (e.g., Python, Go, pre-commit, etc.) and vscode extensions for you. To try it out, launch the terminal in vscode and try a few exercises:

• Run pre-commit run -a to run pre-commit hooks on all files.
• Run make test to run Go unit tests.
• Run docker-compose up --build to run Docker in the devcontainer.
• Add a whitespace to the end of a line in a file, and notice that the space will be automatically removed when you save the file. This is done by the shardulm94.trailing-spaces extension.
• Add a typo or misspelled word to the file, and notice that it will show a warning message for the unknown word. This is triggered by the streetsidesoftware.code-spell-checker extension.

This is great! With the devcontainer configuration, everyone working on the project will have the exact same setup. No more it works on my machine dramas.