domain SSL cert checker | bash script

gistfile1.txt

#!/bin/bash

DOMAINS="nodes.txt"
RECIPIENT="[email protected]"
DAYS="14"

# Mailgun settings
MAILGUN_API_KEY=""
MAILGUN_DOMAIN=""
MAILGUN_URL="https://api.mailgun.net/v3/$MAILGUN_DOMAIN/messages"
# Slack Webhook URL
SLACK_WEBHOOK_URL=""

while read -r TARGET; do
    echo "checking if $TARGET expires in less than $DAYS days"
    expirationdate=$(date -d "$(: | openssl s_client -connect "$TARGET":443 -servername "$TARGET" 2>/dev/null \
                                    | openssl x509 -text \
                                    | grep 'Not After' \
                                    | awk '{print $4,$5,$7}')" '+%Y-%m-%d')
    in14days=$(date -d "+$DAYS days" '+%Y-%m-%d')

    echo "Expiration date: $expirationdate"
    echo "In 14 days: $in14days"

    if [[ "$in14days" > "$expirationdate" ]]; then
        subject="Certificate expiration warning for $TARGET"
        body="KO - Certificate for $TARGET expires in less than $DAYS days, on $expirationdate"

        # Send email using Mailgun
        curl -s --user "api:$MAILGUN_API_KEY" \
             "$MAILGUN_URL" \
             -F from="[ApiVPN] SSL Checker Bot <mailgun@${MAILGUN_DOMAIN}>" \
             -F to=$RECIPIENT \
             -F subject="$subject" \
             -F text="$body"
    # Send message to Slack
        slack_message="Certificate for $TARGET expires in less than $DAYS days, on $expirationdate"
        curl -X POST -H 'Content-type: application/json' --data "{\"text\":\"${slack_message}\"}" $SLACK_WEBHOOK_URL
    else
        echo "OK - Certificate for $TARGET expires on $expirationdate"
    fi
done < "${DOMAINS}"