Fix multi-node cluster not working after restarting docker

In a multi-node cluster with single controlplane node, if the
controlplane node's IP changes, kube-controller-manager and
kube-scheduler would fail to connect kube-apiserver.

enable_network_magic in the entrypoint of the node image has taken care
of fixing up stale IPs in configuration files. This patch does the same
for server address in kubeconfig file. But we update it to loopback
address as the server certificate isn't valid for the new IP.

Signed-off-by: Quan Tian <[email protected]>

images/base/files/usr/local/bin/entrypoint

@@ -372,6 +372,13 @@ enable_network_magic(){
       sed -i "s#${old_ipv4}#${curr_ipv4}#" /etc/kubernetes/manifests/*.yaml || true
       # this is no longer required with autodiscovery
       sed -i "s#${old_ipv4}#${curr_ipv4}#" /var/lib/kubelet/kubeadm-flags.env || true
+      # controller-manager and scheduler connect to local API endpoint. If the Node's IP changes, server address in
+      # kubeconfig should be updated. However, the server certificate isn't valid for the new IP. We update it to
+      # loopback address as it's an alternative address of the certificate.
+      if [[ "${old_ipv4}" != "${curr_ipv4}" ]]; then
+        sed -i "s#${old_ipv4}#127.0.0.1#" /etc/kubernetes/controller-manager.conf || true
+        sed -i "s#${old_ipv4}#127.0.0.1#" /etc/kubernetes/scheduler.conf || true
+      fi
   fi
   if [[ -n $curr_ipv4 ]]; then
     echo -n "${curr_ipv4}" >/kind/old-ipv4
@@ -391,6 +398,13 @@ enable_network_magic(){
       sed -i "s#${old_ipv6}#${curr_ipv6}#" /etc/kubernetes/manifests/*.yaml || true
       # this is no longer required with autodiscovery
       sed -i "s#${old_ipv6}#${curr_ipv6}#" /var/lib/kubelet/kubeadm-flags.env || true
+      # controller-manager and scheduler connect to local API endpoint. If the Node's IP changes, server address in
+      # kubeconfig should be updated. However, the server certificate isn't valid for the new IP. We update it to
+      # loopback address as it's an alternative address of the certificate.
+      if [[ "${old_ipv6}" != "${curr_ipv6}" ]]; then
+        sed -i "s#${old_ipv6}#::1#" /etc/kubernetes/controller-manager.conf || true
+        sed -i "s#${old_ipv6}#::1#" /etc/kubernetes/scheduler.conf || true
+      fi
   fi
   if [[ -n $curr_ipv6 ]]; then
     echo -n "${curr_ipv6}" >/kind/old-ipv6