Kong not get started because of postgres

When ever i am restart the services of postgresql database or reboot the machine.
the postgres comes in running mode but while starting the kong services it gives the error like

error: /usr/local/share/lua/5.1/kong/cmd/start.lua:28 :[Postgres error] could not retrive the current migration : [Postgres error] connection refused.
Run with --v (verbose) or - - vv (debug) form more details

Please help