pingbot.sh

#!/usr/bin/env bash
set -u

echo "Welcome to pingbot v0.0.0"
echo "Monitoring hosts: $HOSTS"

while true; do
  for machine in $HOSTS; do
    machinedir=results/$machine
    mkdir -p $machinedir
    # Make sure files exist without updating mtime
    touch -a $machinedir/failure
    sleep 1s
    touch -a $machinedir/success
    # Do the acutal ping
    if ping -qc2 $machine > /dev/null 2>&1; then
      # Success
      if [ $machinedir/failure -nt $machinedir/success ]; then
        # New success
        echo "$(date) $machine: Newly online"
        curl \
          -X POST \
          -H 'Content-type: application/json' \
          --data "{\"text\" : \":sunglasses: $machine is back online\"}" \
          $SLACK_WEBHOOK
      fi
      touch $machinedir/success
    else
      # Failure
      if [ $machinedir/success -nt $machinedir/failure ]; then
        # New failure
        echo "$(date) $machine: Newly offline"
        curl \
          -X POST \
          -H 'Content-type: application/json' \
          --data "{\"text\" : \":warning: $machine is newly offline\"}" \
          $SLACK_WEBHOOK
      fi
      touch $machinedir/failure
    fi
  done

  sleep 5m
done