"docker.sock" is used to access Docker API which is required to: 1. subscribe to Docker events to configure-arp, 2. query Docker network info to detect whether multicast should be enabled. 3. get list of Swarm peers before starting the plugin. (1) is currently not implemented. (2) is replaced by WEAVE_MULTICAST env var which can enable multicast for all Weave networks created by the plugin (not ideal, but better than nothing). (3) is fixed by not removing "restart.sentinel".
Weave network driver extension for Docker and Kubernetes
This directory implements both a Docker plugin to integrate Weave Net with Docker, and a Container Network Interface (CNI) plugin, to integrate Weave Net with Kubernetes.
The Docker plugin runs automatically when you weave launch, provided your
Docker daemon is version 1.9 or newer.
More detail on the Docker plugin here.
More detail on the CNI plugin here.