entrypoint.sh

#!/bin/bash

function wait_for_it()
{
    echo $1
    local serviceport=$1
    local service=${serviceport%%:*}
    local port=${serviceport#*:}
    local retry_seconds=5
    local max_try=100
    let i=1

    nc -z $service $port
    result=$?

    until [ $result -eq 0 ]; do
      echo "[$i/$max_try] check for ${service}:${port}..."
      echo "[$i/$max_try] ${service}:${port} is not available yet"
      if (( $i == $max_try )); then
        echo "[$i/$max_try] ${service}:${port} is still not available; giving up after ${max_try} tries. :/"
        exit 1
      fi

      echo "[$i/$max_try] try in ${retry_seconds}s once again ..."
      let "i++"
      sleep $retry_seconds

      nc -z $service $port
      result=$?
    done
    echo "[$i/$max_try] $service:${port} is available."
}

#DO NOT DOUBLE QUOTE
for i in ${SERVICE_PRECONDITION[@]}
do
    wait_for_it ${i}
done

exec /usr/bin/supervisord -c /app/supervisord.conf