fixes for bsc#1214406
- update `Wants` directive in [Unit] section of `kubelet.service`:
* add: `containerd.service`
* remove: `docker.service`
- updating container runtime prerequisites:
(Refer: k8s.io/docs/setup/production-environment/container-runtimes/#install-and-configure-prerequisites)
* update `90-kubeadm.conf` to add below iptables rules:
- net.bridge.bridge-nf-call-iptables = 1
- net.bridge.bridge-nf-call-ip6tables = 1
* update `kubeadm.conf` to add `overlay` kernel module
* update .spec file to:
- add post-installation scriptlet for `kubeadm` package to enable iptables rules defined in `90-kubeadm.conf` using sysctl
- add conditional checks to load kernel modules (br_netfilter, overlay) in `kubelet-common` package post-installation scriptlet
- update `kubelet-common` post scriptlet to correctly update `KUBELET_VER` var in `/etc/sysconfig/kubelet` file based on fillup template
- add below to `kubelet` subpackage to recommend installing correct version of package providing `kubernetes-kubelet-common` :
* `Recommends: kubernetes-kubelet-common = %{version}`
- add below to `kubeadm` subpackage to recommend installing correct version of `kubelet` and `kubelet-common` packages:
* `Recommends: kubernetes%{baseversion}-kubelet`