Initiated by the folks of Rancher Labs there's a new stripped-down version of Kubernetes called K3S that is targeted to edge deployments with low resources or other installations which require lower operational complexity than plain Kubernetes. The name of the project is a play on the K8S, the usual abbreviation of Kubernetes, that's supposed to mean "5 less than K8S".
K3S was introduced to the public in a Hackernews post in November, now the CNCF has followed up with a webinar on K3S "Introducing a Lightweight Kubernetes Distribution Built for the Edge".
According to the developers K3S is easy to operate and can run on x86 and ARM infrastructure without using more than 512 MB of memory. Legacy functionality and many plugins have been removed from the Kubernetes code base, and while etcd is still available K3S is using SQLite as the default storage engine.
The source code and instructions about installation can be found on the K3S GitHub repo.
Other lightweight alternatives to the Kubernetes orchestration software include Docker Swarm, Hashicorp Nomad or another indie open source project called Stellar.