Docker privileged:true hangs Ubuntu 20.04

[nurturenature]

Currently have to use volumes: cgroup vs privileged:true or Ubuntu 20.04 hard hangs when docker-composing.

Suspect it's a local dev configuration? (libc6 version or other dependencies that had to be upgraded?)

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Think it's cgroup v1, v2, hybrid, impedance between host Ubuntu hybrid, docker v2, and container Debain hybrid interactions.

Tried forcing Ubuntu to v2:

# edit /etc/default/grub
# GRUB_CMDLINE_LINUX="systemd.unified_cgroup_hierarchy=1 systemd.legacy_systemd_cgroup_controller=0"
sudo update-grub
sudo reboot

All permutations in docker:

# commented out, :ro, :rw  
  volumes:
    - "/sys/fs/cgroup:/sys/fs/cgroup:ro"
# commented out, true, with & w/o cap_add:
privileged: true
cap_add:
  - ALL

With base Ubuntu, privileged:true hangs and required power cycle :warning:.

With GRUB explicitly using cgroup v2, container fails with various cgroup issues depending on privileged, /sys/fs/cgroup settings.

# look at cgroup usage

grep cgroup /proc/filesystems
cat /proc/self/cgroup 
stat -c"%T" -f /sys/fs/cgroup

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Tested with current jepsen/master.

Docker logs

• db nodes clean, all services brought up
• control node sort: cannot read: /var/jepsen/shared/nodes: No such file or directory

Bringing up an individual db node -> :boom: and a power cycle to recover.

[nurturenature]

LXC is required vs Docker.