WebAssembly in Action

Author of the book "WebAssembly in Action"
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The book's original source code can be downloaded from the Manning website and GitHub. The GitHub repository includes an updated-code branch that has been adjusted to work with the latest version of Emscripten (currently version 3.1.44).

Wednesday, April 14, 2021

From ConFoo to deploying web applications with Docker

The story of how discovering Docker helped me create the demos for my ConFoo 2021 presentation about the WebAssembly System Interface (WASI). Then the continued learning about Windows containers resulting in my latest Uno Platform article about Deploying C# web applications with Docker.
In 2020, ConFoo opened a call for papers for their February 2021 conference. I submitted several proposals and was pleased to find out in January 2021 that one of them had been accepted.

The talk was going to be about the WebAssembly System Interface (WASI). I knew what I wanted to talk about but I wanted a couple demos that were more real-world than the typical 'hello world' style. I had an idea for the applications I wanted to write but, to write them, I needed to compile some C libraries. Unfortunately, I was having some difficulties getting things set up on Windows.

My first thought for a workaround was to set up a Linux virtual machine but I was curious if there was another way. One thought that crossed my mind was, can Docker help here?


I had seen Docker demonstrated at a couple user group events but I hadn't used it myself so I needed to get up to speed quickly. Thankfully, I found the following YouTube video that not only explained the Docker theory but also walked through several examples that I was able to follow along with: https://www.youtube.com/watch?v=3c-iBn73dDE

After watching the video, I started looking though the images on Docker Hub and discovered that there's a Docker image for the Emscripten SDK. This is useful to me for a couple of reasons:
  • I prefer to have Emscripten use the versions of the tools it installed rather than a different version on my machine just in case the changes impact things when compiling a module. Being in a container, all the tools Emscripten needs are in the container with it allowing me to adjust the tools on my machine as needed.
  • I often switch between versions of Emscripten to test different things. Having an image for each version I need makes things a lot easier. Sometimes I've had to uninstall a version of Emscripten before being able to install the next one. Now, I just need to pull and run the image with the version I need.

In the end, I created a Docker image derived from an Emscripten image and was able to build the demos I wanted for my ConFoo talk.

A few days before the ConFoo conference started, I was talking with the Uno Platform team about Docker. I thought Docker might be useful for C# developers for one-click deployment because I saw on Docker Hub that there was an image with IIS (Internet Information Services).

An article about Docker

After the conference was over, I started looking into Docker from a C# perspective. Unfortunately, every time I tried to build a Windows Docker image, I'd get errors. I spent a number of evenings reading about Windows containers and trying different things but kept spinning my wheels.

I learned a lot about Windows containers in the process but I felt a little dumb when I ran across an article that explained my problem. It turns out that you can't create Linux and Windows containers at the same time. You need to switch Docker Desktop to use one or the other and I was trying to create a Windows container while configured for Linux.

Today, I'm pleased to announce that my latest article "Deploying C# Web Applications with Docker" has been published on the Uno Platform's blog. The article walks you through building an image with IIS and .NET Core, publishing it to a private registry, pulling the image, and running the container.

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