The Size Paradox: 4 Techniques to Slim Down Windows Container Images

In our previous post, we discussed my experience working with Windows Containers, and why it was the most viable bridge to the cloud when trying to modernize your applications (.NET Framework). Sometimes, in a world where Linux images are measured in megabytes, seeing a Windows build log report a 5GB image can be a bit shocking. For us, as software engineers, image size isn't just about disk space, it’s about deployment velocity. A 5GB image means slower cold starts in Kubernetes, longer CI/CD wait times, and higher egress costs. Here is how we managed to lower those numbers down by modifying our Dockerfiles. The Base Image One of the most important decisions is made in the very first line of the Dockerfile. Microsoft provides four primary images, and choosing the wrong one can cost you up to 4GB before you even add your code (Yes, that's true). Base Image Typical Size Use Case Nano Server ~100MB The "Alpine" equivalent of Windows. Built for the newest .NET versions (.NET 6+). No Power