Script to wait for a host to become available locally

docker_wait_hosts.sh

wait_single_host() {
  local host=$1
  shift
  local port=$1
  shift

  echo "==> Check host ${host}:${port}"
  while ! nc ${host} ${port} > /dev/null 2>&1 < /dev/null; do echo "   --> Waiting for ${host}:${port}" && sleep 1; done;
}

wait_all_hosts() {
  if [ ! -z "$WAIT_FOR_HOSTS" ]; then
    local separator=':'
    for _HOST in $WAIT_FOR_HOSTS ; do
        IFS="${separator}" read -ra _HOST_PARTS <<< "$_HOST"
        wait_single_host "${_HOST_PARTS[0]}" "${_HOST_PARTS[1]}"
    done
  else
    echo "IMPORTANT : Waiting for nothing because no $WAIT_FOR_HOSTS env var defined !!!"
  fi
}

wait_all_hosts