Add a check in `check-config.sh` to see if we are running on a RHEL7 or
CentOS7 system, which may report that CONFIG_USERNS is OK/enabled, but
user namespaces still won't work because of the experimental feature
flag added by Redhat.
This will add a warning if it is actually disabled and notes what has to
be added to the grub/boot command line to enable it.
Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)
Upstream-commit: 23551515564b54128e882dda5eae659883947d39
Component: engine