Kubernetes add new node error “following required kernel modules are not loaded: [ip_vs_rr ip_vs_wrr ip_vs_sh ip_vs] or no builtin kernel ipvs support”

Today I was working on our PaaS doing regular stuff, then I was assigned to add a new node to kubernetes cluster.
The whole process was automated already by me with help of Ansible, so it was not a big deal.
After mounting storage, its k8s turn to have this new node. Process was easy, ansible need to install prerequisite on node and get join command from master to run it on new node.
Well everything looked perfect until run join command on the node. yeah problem was this:

Well, Missing kernel module? are you kidding me. we already have lots of nodes, where the heck this kernel missing module came from ?
after almost two hours of wasting time i figured out what the problem was. Yeah kubelet ! just a minor version difference!!! our master and other nodes were running on v1.11.2 and the installed one on the new node was v11.12.
after downgrading new node to v1.11.2 everything started to work smoothly again.
Conclusion: Always check what version your cluster and all dependencies running on. install the same version on new nodes or upgrade all together with same the version.

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