This is the Docker application deployment mechanism.

AppArmor profiles have been moved to /var/lib/apparmor/profiles, default profile has been modified.

Data is stored in /var/lib/apps/docker/${version_of_snap_package}/ (symlinked to /var/lib/apps/docker/current).

If you need to pass through proxies or adjust default DNS for your containers, edit /apps/docker/current/etc/docker.conf accordingly and restart the Docker daemon service:

FTP_PROXY=http://your.proxy:3128
HTTP_PROXY=http://your.proxy:3128
HTTPS_PROXY=http://your.proxy:3128
DOCKER_OPTIONS="--dns 8.8.8.8"

Restarting the daemon can be accomplished via sudo systemctl restart docker_docker-daemon_${version_of_snap_package}.service.

If you need privileged access in containers (docker run --privileged), you can issue docker-privilege on (disable again with docker-privilege off and check the current configuration with docker-privilege status); however, be forewarned: the confinement will be nearly nonexistent (full root access to the host system is possible).