Troubleshooting some frequent problems with Docker.

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= 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) 

= tar cannot change ownership =

Problem: the tar command wants to preserve ownership, but has problems even as root because auf UID and GID mismatches.

Solution: add the option --no-same-owner at the end(!) of the tar command

Source: https://www.krenger.ch/blog/linux-tar-cannot-change-ownership-to-permission-denied/