Sending VMware vCenter Alerts to Telegram/Discord – Part 2

Now it’s the hard part on how to redirect the email alerts to Telegram or Discord. As Discord provides webhooks directly, we can format the the received email stream and then use the curl command to send the alert to Discord.

We can get the webhook from Copy Webhook URL.

As said in the previous post we can forward an email to a script, we now do this through vCenter’s built-in Sendmail server and use an email alias to do it. The aliases file is the file to do it and it is located in /etc/mail/aliases on vCenter. Add an entry like the following in aliases.

vm-alert: "| /usr/local/bin/send-alert VCenter"

The above will forward the email stream to the script file /usr/local/bin/send-alert after the command “newaliases” is run to add the entry to the aliases db.

Before we write our script to process the email stream and send to Discord, we need to know the content of a typical email. The following is an example alert from vCenter.

A typical email has extra headers that are not needed in the alert text. So our script file has to address this.

The following is my script with minor changes.

#!/bin/bash

HEADER=`echo -n "\n**$1:**  \n\n"`
TIMESTAMP=`date +%Y-%m%d-%H%M.%S`
FILE="/dev/shm/mail-${TIMESTAMP}"

STATS=https://discord.com/api/webhooks/124521219726154XXXX/ht4ZiRUEFYbgQ4YDU9mUl1rtcdLsNGVFB95XW_UKIICd5Xppf-QvwzlMEqn-xxxxxxxx
WARNING=https://discord.com/api/webhooks/124556384469752XXXX/3pzyh5NuQdqnJD8zuqI8a44JR608rPAdXXQHBu7oqToNvJW4v9OzI0ubeylzXxxxxxxx

### This redirects the email stream to a file.
sed '' > $FILE

MSG=$(sed '/^From /,/^To:/d' $FILE | sed '2,/^$/d' | sed 's/^Subject.*/&\n/' | sed 's/$/\\n/' | tr -d '\n')
MSG="${HEADER}${MSG}"

### 
grep MIME-Version $FILE

if [ $? -eq 0 ]
then
        exit
fi

###
grep "New Status: Red" $FILE

if [ $? -eq 0 ]
then
        curl -H "Content-Type: application/json" -d "{\"content\": \"$MSG\"}" $WARNING
else
        curl -H "Content-Type: application/json" -d "{\"content\": \"$MSG\"}" $STATS
fi

rm $FILE

After the script is ready and set to executable, the same email stream shown in the above screenshot will result in a Discord message like the screenshot shown below.