After updating GitLab and GitLab Runner to v15.8.1 on a Ubuntu 20.04.05 LTS suddenly none of our pipelines succeeded anymore.
Every job showed the following error message:
ERROR: Preparation failed: adding cache volume: set volume permissions: running permission container "XXXXXXX" for volume "runner-zx-dagtx-project-41-concurrent-0-cache-YYYYYYY": starting permission container: Error response from daemon: AppArmor enabled on system but the docker-default profile could not be loaded: running
apparmor_parser apparmor_parser --versionfailed with output: error: exec: "apparmor_parser": executable file not found in $PATH (linux_set.go:105:0s)
Google miss leaded me to re-installations of Docker and the GitLab Runner, to deleting all docker volumes, images and containers and so on. All without success.
How to get GitLab Runner back to work?
What fixed the problem was the installation of AppArmour and the AppArmour Utilities.
sudo apt-get install apparmor apparmor-utils
Another solution would have been to disable AppArmour during the boot process by adding apparmor=0 as boot parameter to the grub file (what I didn't try, so no guarantee for that).