Container technology was major news last year, and if you bring up the container arena to most people, Docker is what they think of. OStatic has highlighted some of Docker's instabilities, though, and, as noted in this post, significant competition is coming in Docker's direction.
Google has set its sights on Docker by transforming its Kubernetes platform into a full-fledged part of Google Cloud Platform with Google Container Engine. Canonical is leaping into the into the virtualization arena with a new hypervisor called LXD that uses the same Linux container tools that have allowed Docker to isolate instances from one another. Also, we've reported on how the CoreOS team is developing a Docker competitior dubbed Rocket. Rocket is a new container runtime, designed for composability, security, and speed, according to the CoreOS team. Here is more about Rocket, and whether it is intended to compete with Docker.