downtime-monitor.sh : Monitor HTTP status changes on some URL with curl

downtime-monitor.sh

#!/bin/bash

#
# request some URL and report HTTP status changes
# ./downtime-monitor.sh https://some.url
#

URL="$1"

INTERVAL=0.1
TIMEOUT=1

_COUNT=0
_LAST_STATUS="";
_LAST_STATUS_DATE="";
while (true); do
    printf "."
    _STATUS=$(curl -L --max-time $TIMEOUT --connect-timeout $TIMEOUT -o /dev/null --fail --silent --show-error -w "%{http_code}" "${URL}")
    _COUNT=$((_COUNT+1));
    NOW=$(date +"%Y%m%dT%H:%M:%S")
    if [ "$_LAST_STATUS" != "$_STATUS" ]
    then
      if [ "$_LAST_STATUS" ]
      then
        printf "\n%s: status : %s -> %s after %s requests (since %s)" "$NOW" "$_LAST_STATUS" "$_STATUS" "$_COUNT" "$_LAST_STATUS_DATE"
      else
        printf "\n%s: status : %s" "$NOW" "$_STATUS"
      fi
      #printf "\n%s: ⚠️ status %s" "$NOW" "$_STATUS";
      _COUNT=0
      _LAST_STATUS_DATE="$NOW"
    fi
    _LAST_STATUS="$_STATUS";
    sleep $INTERVAL;
done;