wtf is docker-upx?

This project packages a popular file-compression tool called UPX into a ready-to-use container, and cleverly uses that same tool to shrink its own size. UPX is an open-source program that makes executable files, think of those as ready-to-run applications, smaller, so they take up less storage space and download faster. At a high level, the project uses a two-step build process. In the first stage, it compiles the UPX program from scratch. Then it runs that freshly built copy of UPX on itself, compressing the program down to a more compact version. This kind of setup is useful because it produces a self-contained, portable package that anyone can grab and use without needing to set up a build environment or compile code themselves. The main audience is developers or technical tinkerers who already work with containerized applications and want an easy way to compress their own executable files. For example, if you have a small application you want to distribute, you could use this tool to run UPX's compression on it, making the final file significantly smaller. You can also pull the pre-built tool directly into your own project setup, dropping it in as a single step to get a working copy of UPX without any extra configuration. What stands out is the clever, self-referential approach: using the compression tool to minimize its own footprint. It is a small, focused utility with a single job, designed to be grabbed and used quickly rather than being a large, feature-rich platform.