Adding HTTP check

wait.sh

#!/bin/bash

set -e

sleep_seconds=2

function usage() {
  echo "Usage: ./wait <tcp/http> <host>:<port>"
}

function check() {
  if [[ -z "$1" ]]; then
    echo "Error: invalid $2"
    usage
    exit 2
  fi
}

function tcp() {
  IFS=: read -r host port <<< "$1"
  while ! nc -z $host $port; do
    echo "Waiting TCP connection to $host:$port"
    sleep $sleep_seconds
  done
}

function http() {
  while [[ "$(curl -s -o /dev/null -I -w ''%{http_code}'' $1)" != "200" ]]; do echo "Waiting HTTP connection to $1" && sleep $sleep_seconds; done
}

if [[ $# -eq 0 ]]; then
  usage
  exit 1
fi

check "$2" "host:port"

case "$1" in
'tcp') tcp $2 $3 ;;
'http') http $2 $3 ;;
*) usage ;;
esac