FAQ

Why wctr?

wctr is the command line and wctrd the daemon that serves it. The name follows the convention of the container tools that came before it, ctr, nerdctl and crictl: a short name ending in ctr, for container. The w is for wasm: wctr reads as wasm container, and says that this is the WebAssembly variant.

Not docker

Docker is a product and a trademark of another organisation. This engine is not Docker and does not ship under its name: it is compatible with the Docker Engine API, which is a statement of compatibility and nothing more. That is why its socket is /var/run/wctr.sock and the address variable is WCTR_HOST.

Not ctr

ctr is the command line that containerd ships. Trainees meet it on Kubernetes nodes, where it means something different, so a lab teaching a ctr of its own would teach the wrong tool in the place they will use it.

Does anything work with existing Docker clients?

The API is meant to be compatible with the Docker Engine API (v1.47 is the reference the code is written against), so a client of that API can be pointed at /var/run/wctr.sock. Only the subset M1 needs is planned first; see the roadmap.