wait-for.sh

#!/bin/bash

set -e

hostport=(${1//:/ })
host=${hostport[0]}
port=${hostport[1]}
shift
cmd="$@"

if [[ "$host" == "" || "$port" == "" ]]; then
    echo "Usage: $0 host:port cmd"
    exit 1
fi

while ! nc -z $host $port; do
  >&2 echo "Service is unavailable - sleeping"
  sleep 1
done

>&2 echo "Service is up - executing command"
exec $cmd