containerd is, in its own words, “an industry-standard container runtime with an emphasis on simplicity, robustness and portability.” It runs as a daemon on Linux and Windows and manages the complete container lifecycle on a host: image transfer and storage, container execution and supervision, and low-level storage and network attachments.
The project was extracted from Docker’s own platform. On March 29, 2017, at CloudNativeCon and KubeCon Europe in Berlin, the Cloud Native Computing Foundation announced that Docker had contributed containerd to the CNCF, where its Technical Oversight Committee accepted it as an incubating project. The CNCF described it as “Docker’s core container runtime,” extracted to provide “an open, stable and extensible base for building non-Docker products and container solutions” and noted it served as “a key foundation for Kubernetes.”
By design, containerd sits beneath higher-level tools rather than facing end users directly. Docker uses it under the hood, and Kubernetes can drive it through the CRI (Container Runtime Interface). It in turn shells out to a lower-level runtime such as runc to actually create and run the container according to the OCI runtime specification.
containerd graduated within the CNCF on February 28, 2019, joining the foundation’s most mature tier alongside projects such as Kubernetes and Prometheus.