Robust way of opening an closing ssh tunnels without having to depend on active connections

open-and-keep-alive.sh

#!/usr/bin/env bash
#set -x # for debugging

SSH_HOST="user@www.sample.com"

# using -f and -o exitOnForwardFailure is helpful, but if you are managing processes that restart and you want to keep
#   the tunnel open even after a restart this can be difficult (e.g. nodemon with a remote mongo, mysql, elasticsearch, etc)
#
# instead you can open the tunnels and close them on script exit

echo "opening ssh tunnels"
(ssh -N -L 27018:localhost:27017 -M -S /tmp/ssh_tunnel_27018_%h.sock $SSH_HOST)&
(ssh -N -L 9200:localhost:9200   -M -S /tmp/ssh_tunnel_9200_%h.sock  $SSH_HOST)&

function finish {
  echo "closing ssh tunnels"
  ssh -S /tmp/ssh_tunnel_27018_%h.sock -O exit $SSH_HOST
  ssh -S /tmp/ssh_tunnel_9200_%h.sock  -O exit $SSH_HOST
}

trap finish EXIT