[Update] Adding Alpine Linux support for IPv6 NAT migration (#4244)

Added restart options via openrc

update.sh

@@ -169,11 +169,16 @@ migrate_docker_nat() {
       echo "Working on IPv6 NAT, please wait..."
       echo ${NAT_CONFIG} > /etc/docker/daemon.json
       ip6tables -F -t nat
-      if ! systemctl restart docker.service; then
+      [[ -e /etc/alpine-release ]] && rc-service docker restart || systemctl restart docker.service
+      if [[ $? -ne 0 ]]; then
         echo -e "\e[31mError:\e[0m Failed to activate IPv6 NAT! Reverting and exiting."
         rm /etc/docker/daemon.json
-        systemctl reset-failed docker.service
-        systemctl restart docker.service
+        if [[ -e /etc/alpine-release ]]; then
+          rc-service docker restart
+        else
+          systemctl reset-failed docker.service
+          systemctl restart docker.service
+        fi
         return 1
       fi
     fi