shell function to check if a instance is sshable (can be used for cloud instaces)

sshable_function.sh

function sshable () {
  [[ $# -ne 3 ]] && { echo "requires instance, ssh_user, ssh_key arguments"; return; }
  instance=$1
  ssh_user=$2
  ssh_key=$3
  command=$(ssh -t -t -o ConnectTimeout=2 -o StrictHostKeyChecking=no -o BatchMode=yes -o UserKnownHostsFile=/dev/null -p 22 -i ${ssh_key} ${ssh_user}@${instance} "echo" &>/dev/null)
  until $command; do
    echo -e ".\c"
  done
  echo ""
  echo "Instance ${instance} is now shhable"
}

This function can be used in startup scripts and can be used as a command.

Fix: this function hangs indefinitely, add timeout logic