Major changes

Update kubernetes version to 1.21.6 (#8142, @oomichi)
Add a new option metrics_server_resizer (default to false) to control the addon-resizer container deployment in metrics-server pod (#8018, @oomichi)
Add an optional fallback to node drain during cluster upgrades using --disable-eviction flag (#8102, @utkuozdemir)
Ensure apparmor is installed on Ubuntu (#8036, @rtsp)
Default DNS replica count is now set to the minimum value between 2 and the length of k8s_cluster inventory group (#8109, @smasset)

Applications

[Openstack] Fix a bug where Openstack cloud provider could not be used with username/password (#8021, @bl0m1)

[Calico] Check if 'plugins' key exists in calico_cni_config object allowing user to add nodes using both playbooks (#7717, @dlouks)
[Calico] Fix typha prometheus causing a deployment error (#8005, @ericlake)
[Calico] Increase node probe timeouts and add calico_node_readinessprobe_timeout/calico_node_livenessprobe_timeout to tune them (#7981, @cristicalin)
[Cilium] Fix operator metrics activation (enable-metrics key missing) (#8000, @L3o-pold)

Add missing proxy settings for subscription-manager in RHEL OS (if http_proxy is defined) (#8012, @oomichi)
Fix CentOS7 issue with allowPrivilegeEscalation value from metrics-server (#8014, @oomichi)
Fix k8s-certs-renew cp path wrongly using /usr/bin/ (#7992, @lazybetrayer)
Fix containerd failed to start if apparmor is not installed (#8011, @rtsp)

Use kube_config_dir for kubeconfig instead of hard path in multiple plays (#7996, @oomichi)