This comes with a "no blame - no claim" warning, proceed at your own risk. Mistakes can render your "Docker VM" un-bootable. My test was done on FreeNAS11.2-U3 only.
Assumption: you have already created at least one "Docker VM" on your system.
1. Within your "Docker VM" use the appropriate ros command to upgrade to v1.5.1 Answer "NO" to re-boot now, and "poweroff" the docker VM. (Repeat for each Docker VM already installed)
2. Locate the grub.cfg file associated with each "Docker VM" within the hidden dataset .bhyve_containers in your pool. Edit grub.cfg to update the kernel to 4.14.85 and initrd to 1.5.1
3. Edit system file /usr/local/lib/python3.7/site-packages/middlewared/plugins/vm.py to update the
grub_additional_args at lines 516-517, replacing the vmlinuz and initrd numbers with 4.14.85 and 1.5.1 respectively.
Restart your Docker VM and it should boot into the upgrade version 1.5.1
Things to consider:
AFAIK all Docker VMs must run with the same rancheros version, as the system can only create the same fixed grub.cfg for each VM. If you have more than one Docker VM you must repeat step 1 for each VM before carrying out steps 2 &3. After making these changes you cannot create a new "Docker VM" without first shutting down all upgraded 1.5.1 docker Vms, and reversing the changes in step3. Then after Installing the new "Docker VM" , follow steps 1,2 and 3. (I have not properly tested this action)
