On my test cluster: 3 RKE servers (Master + Node) and 1 Rancher server.
After an ubuntu upgrade, I got a not supported docker version.
The upgrade has no impact on the RKE cluster.
NAME STATUS ROLES AGE VERSION EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME 192.168.1.34 Ready controlplane,etcd,worker 1d v1.10.1 <none> Ubuntu 16.04.4 LTS 4.13.0-45-generic **docker://18.3.1** 192.168.1.39 Ready controlplane,etcd,worker 1d v1.10.1 <none> Ubuntu 16.04.4 LTS 4.13.0-45-generic docker://1.13.1 192.168.1.55 Ready controlplane,etcd,worker 1d v1.10.1 <none> Ubuntu 16.04.4 LTS 4.4.0-128-generic docker://17.3.2
I got docker version 18.3.1 not supported by Rancher.
If I like to install a new RKE version than the installation shall fail because of the docker version checks of the installation programs.
At the moment it seems that the snap releases are still in line, but snap cannot be used because of permission problems.
A solution is needed!