Permission denied while deploying/activating docker image in Rancher-Kubernetes
That's the problem, you are not running as 'root' and the container entrypoint executes a call to setgroups which requires 'root'. You will have to either run as 'root' somehow or you can modify your container image and the entrypoint to perhaps make those calls where 'root' is require using something like 'sudo'.
Note that whatever user call 'sudo' needs to have 'root' like permissions to execute setgroups