Checkpoint/Restore on Mac findings

[ghost]

I'm running Version 17.09.0-ce-mac35 (19611) and I wanted to post my findings because I was troubleshooting for a loooong time. This is not an issue with this repo, just a reference for others.

-When a checkpoint directory is not specified, the checkpoint lives inside the docker VM.

-If CRIU crashes and a checkpoint directory is specified, the crash log is inaccessible (fails to map the file I believe). I docker'd into the Docker VM by using:

docker run -it --privileged --pid=host debian nsenter -t 1 -m -u -n -I sh

Then copied my checkpoint into the VM to avoid this issue. Then if CRIU crashes, you docker back into the VM to access the log.

-I accessed the Docker API using a nodejs client and the default network adapter caused a CRIU crash. Setting the network adapter to Host solved the crash.