Troubleshooting some frequent problems with Docker.

A dependency job for docker.service failed (on etna)

Problem: cannot start docker.dock service (we don't yet understand why).

Workaround: sudo dockerd (followed by Ctrl+Z and bg)

Cannot write /home/<user>/.docker

Problem: sudo on Machine X != ustica cannot write /home/<user> (different root users on different machines)

Solution 1: Remove /home/<user>/.docker (not sure whether this always works)

Solution 2: sudo docker --config /tmp build -t <name> . (and maybe also for sudo docker run)