Re-visiting Dev Container Features

A few months ago I wrote a post that described how you can add custom features to your Dev Containers. That didn’t age very well 😅

But good news is that there is a better way to add or extend functionality for your Dev Containers. 🥳

Since my original post, @BrigitMurtaugh published a post on the VS Code blog announcing new repos, the open dev container specification and discussed a new way of adding features. If you haven’t read the post, go check it out here.

Exploring .NET WebAssembly with WASI

Overview

WebAssembly (Wasm) is something that the Cloud Native Advocacy team has been exploring. It has been around for a few years and has mostly been used within browser-based applications. There are many blog posts on what makes WebAssembly an ideal target for running applications (e.g., smaller footprint with .wasm files compared to containers, code isolation, and sandboxing). My colleague Steven Murawski wrote a blog series on getting started with hosting Wasm apps on an emerging PaaS platform called Hippo which is developed by folks at Fermyon. In Part 1 of the series, he introduces topics and define some of the acronyms like “Wagi” and “WASI”. He also introduced a runtime called Wasmtime which implements the WebAssembly System Interface (WASI) standard. This article will walk you through how Steven and I went about getting a .NET console app running as a Wasm app on the Wasmtime runtime in a Dev Container. The .NET console app produced in this article has also been contributed as a csharp template in the yo-wasm repo which is also maintained by Fermyon; so you can quickly test it out for yourself later.

Extending Visual Studio Code Dev Container Features

UPDATE: The dev-container-features-template repo referenced in this post has been archived. Please see my new post here or visit containers.dev for the latest on this topic.

Have you ever wanted to try an Azure CLI extension without having to install the extension yourself on your local machine? VSCode Dev Containers may be a good option.

What is a Dev Container?

Visual Studio Code has an extension called Remote - Containers. This extension lets you use a Docker container as a development environment and is the technology that powers GitHub Codespaces. If you don’t have the option to use Codespaces, the remote container technology also allows you to open build/open the container within your local environment as long as you have Docker Desktop,or Rancher Desktop (with dockerd as the container runtime since containerd will not work with remote containers), or Docker Engine running on your local machine.