Docker vs rkt: What are the differences?

Developers describe Docker as "Enterprise Container Platform for High-Velocity Innovation". The Docker Platform is the industry-leading container platform for continuous, high-velocity innovation, enabling organizations to seamlessly build and share any application — from legacy to what comes next — and securely run them anywhere. On the other hand, rkt is detailed as "App Container runtime". Rocket is a cli for running App Containers. The goal of rocket is to be composable, secure, and fast.

Docker and rkt belong to "Virtual Machine Platforms & Containers" category of the tech stack.

Some of the features offered by Docker are:

• Integrated developer tools
• open, portable images
• shareable, reusable apps

On the other hand, rkt provides the following key features:

• Composable. All tools for downloading, installing, and running containers should be well integrated, but independent and composable.
• Security. Isolation should be pluggable, and the crypto primitives for strong trust, image auditing and application identity should exist from day one.
• Image distribution. Discovery of container images should be simple and facilitate a federated namespace, and distributed retrieval. This opens the possibility of alternative protocols, such as BitTorrent, and deployments to private environments without the requirement of a registry.

"Rapid integration and build up" is the primary reason why developers consider Docker over the competitors, whereas "Security" was stated as the key factor in picking rkt.

Docker and rkt are both open source tools. It seems that Docker with 53.8K GitHub stars and 15.5K forks on GitHub has more adoption than rkt with 8.68K GitHub stars and 829 GitHub forks.