We usually think about successful open source in terms of user adoption, level of community contributions, or even vanity metrics like GitHub stars. But what if the success of many of the most popular open source projects in the cloud native ecosystem lies in the ability of external consumers to extend the project in ways the creators didn’t even envision?

In this talk we’ll look at the containerd project and its intentionally designed extensibility. These extensible capabilities have become key launching points for innovation created and even maintained outside of the core project. We’ll look at the details of our snapshotter and shim interfaces, two popular ways to extend containerd that have many examples after 10 years of project development. New features will be demonstrated that utilize these interfaces such as native macOS support that uses the brand new "nerdbox" shim and the erofs snapshotter.

We'll detail the concrete value provided by extensibility and invite other project creators and maintainers to consider how they are designing for extensibility to enable innovation.