Check docker unixsocket periodically through monit. If failed, restart docker.

cluster/saltbase/salt/monit/docker

@@ -3,4 +3,6 @@ group docker
 start program = "/etc/init.d/docker start"
 stop program = "/etc/init.d/docker stop"
 if does not exist then restart
-
+if failed unixsocket /var/run/docker.sock
+  protocol HTTP request "/version"
+  then restart