Reroute dynamic docker port to fixed local port

reroute.sh

function pgreroute() {
  re=':::([0-9]{1,5})->5432';
  [[ $(docker ps -f "expose=5432") =~ $re ]];
  port=${BASH_REMATCH[1]};
  sudo iptables -t nat -I PREROUTING -p tcp --dport 5432 -j REDIRECT --to-ports $port;
  sudo iptables -t nat -I OUTPUT -p tcp -o lo --dport 5432 -j REDIRECT --to-ports $port;
}