A script to check ngrok and reset if necessary.

run_ngrok.sh

#!/usr/bin/env bash
#
#
SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
set -xe
NGROK_DIR=${SCRIPT_DIR}/ngrok
mkdir -p $NGROK_DIR || true
NGROK_CONFIG=${NGROK_DIR}/ngrok.yml

which ngrok || brew install ngrok
which jq || brew install jq

PARAMS=""

while (( "$#" )); do
  case "$1" in
    -c|--config)
      if [ -n "$2" ] && [ ${2:0:1} != "-" ]; then
        NGROK_CONFIG=$2
        shift 2
      else
        echo "Error: Argument for $1 is missing" >&2
        exit 1
      fi
      ;;
    -*|--*=) # unsupported flags
      echo "Error: Unsupported flag $1" >&2
      exit 1
      ;;
    *) # preserve positional arguments
      PARAMS="$PARAMS $1"
      shift
      ;;
  esac
done
# set positional arguments in their proper place
eval set -- "$PARAMS"


function get_proxy_url() {
    # Check ngrok's api for the alexa tunnel
    # See: https://ngrok.com/docs#list-tunnels
    echo $(curl -s http://localhost:4040/api/tunnels |jq '.tunnels[] | select(.name=="demo") | .public_url' -r || echo "")
}


# Use ngrok for the proxy to the laptop. https://ngrok.com/
#
# Run ngrok
#
proxy_url=$(get_proxy_url)
# If a ngrok proxy is running then check if it has an active session
if [ ! -z ${proxy_url} ]; then
    proxy_status_code=$(curl -s -o /dev/null -I -w "%{http_code}" $proxy_url || echo 0)
    if [ $proxy_status_code == 402 ]; then proxy_url=""; fi
fi
if [ -z ${proxy_url} ]; then
    NGROK_PID=$(cat ${NGROK_DIR}/ngrok.pid || echo "")
    if [ ! -z ${NGROK_PID} ]; then kill ${NGROK_PID} || true; fi
    ngrok start alexa --config ${NGROK_CONFIG} >> ${NGROK_DIR}/ngrok.log 2>&1 &
    echo $! > ${NGROK_DIR}/ngrok.pid
    sleep 1
    proxy_url=$(get_proxy_url)
fi