Gets a list of domains with curl, sending an email if the curl exit code is non-zero

check_domains.sh

#!/bin/bash

ERROR_EMAIL="billg@microsoft.com"

DOMAINS=(
  "https://github.com"
)

ERRORED_DOMAINS=()

# joins the rest of the input args with the first arg
function join_by { local IFS="$1"; shift; echo "$*"; }

for i in "${DOMAINS[@]}"
do
  DOMAIN="$i"
  curl --silent --output /dev/null $DOMAIN
  STATUS="$?"
  if [ "$STATUS" -ne 0 ]; then
    echo "`date +\"%Y-%m-%d %H:%M:%S\"` $DOMAIN curl-exit-code=$STATUS"
    ERRORED_DOMAINS+=("$DOMAIN curl-exit-code=$STATUS")
  else
    echo "`date +\"%Y-%m-%d %H:%M:%S\"` $DOMAIN curl-exit-code=$STATUS"
  fi
done

if [ ${#ERRORED_DOMAINS[@]} -eq 0 ]; then
    echo "`date +\"%Y-%m-%d %H:%M:%S\"` No errors found"
else
    echo "`date +\"%Y-%m-%d %H:%M:%S\"` Errors found, emailing $ERROR_EMAIL"
    BODY=$(join_by $'\n'  "${ERRORED_DOMAINS[@]/#/}" "$1")
    echo "$BODY" | mail -E -s "check_domains error" $ERROR_EMAIL
fi