CoreOS – a 2013 San Francisco startup backed by Google Ventures and $20 million in funding – is offering an alternative to the wildly popular Docker application container runtime that is sweeping the market.
Alex Polvi, CEO of CoreOS, says the company has developed a more security-conscious way to run application containers compared to Docker, which they call rkt. CoreOS released the 1.0 general availability open source release of rkt on Thursday.
“The way we approach open source software is that we build modular components,” says Polvi, who before starting CoreOS ran Rackspace’s Bay Area product team. Rkt is one of those components. To understand CoreOS, it’s helpful to understand where rkt fits in CoreOS’s broader offerings.
The company started by developing CoreOS – a Linux-based operating system meant for the new world of distributed computing. As application containers took off, Polvi and his team were less than impressed with some of the design decisions made by Docker, which has been the dominant container company.
So, CoreOS began developing rkt. It’s different from Docker in a couple of different ways. For example, Docker uses a daemon architecture that provides root access to Linux. Poliv says that’s not such a good idea: If Docker is downloading container images from the Internet, there should be some buffer between images downloaded and the container runtime in case one of those images is nefarious. Rkt, on the other hand, downloads the container image, but there’s a separate process for executing it. Polvi says CoreOS is “borrowing decades of Unix best practices” to make rkt.
The broader point here is that CoreOS is trying to provide a market alternative for Docker’s application container runtime. Is it more secure? Well, many customers have found secure ways to run Docker, so it’s not like Docker is not safe. But a market of options is good.
CoreOS has other projects too. In addition to the aforementioned CoreOS Linux operating system, the company also sells a packaged distribution of CoreOS, rkt and the open source container orchestrator Kubernetes. That package is named Tectonic. CoreOS has a container image library it sells too.
Containers continue to be a hot topic in application development and infrastructure management, expect to hear more about CoreOS vs. Docker.