Wait for a port to be open (i.e. for the db to be ready)

wait-port.sh

#!/bin/bash
set -e

echo "Waiting for port opening on ${1}:${2}..."

function check_port() {
    local host=${1} && shift
    local port=${1} && shift
    local retries=90
    local wait=1

    until( $(nc -zv ${host} ${port}) ); do
        ((retries--))
        if [ $retries -lt 0 ]; then
            echo "Service ${host} didn't become ready in time."
            exit 1
        fi
        sleep "${wait}"
    done
}

check_port ${1} ${2}

echo "PORT ${2} is open"