Comments, comments everywhere.

dns_updater.sh

@@ -1,11 +1,31 @@
 #!/bin/bash
+#
+#. Description:
+#.      This script will keep a CloudFlare DNS record up to date with your current public IP address
+#.      It will use 'dig' to query the IP address for the DNS record, then compare that IP to your current public IP.
+#.      If the two IP's do not match, the DNS record will be updated with the current IP address via
+#.      Cloudfare's API.
+#
+#. Usage:
+#.      Enter your details for the variables below, then schedule this script to run every 15 or 30 min via cron.
+#.      The script will output Success/Failure/Skip details that can be easily redirected to a log file.
+#
+#.      Example Crontab Entry:
+#.              */15 *       * * *   root    /path/to/dns_updater.sh >> /var/log/dns_updater.log 2>&1
+#
+#. Author: Rich Oberholtzer (2/2021)
 
 CLOUDFLARE_API_KEY="API KEY HERE"
 AUTH_EMAIL="user@example.com"
-#Can be found by logging in to your Cloudflare, click the site/zone, scroll down to the bottom.  You'll see if on the right side
+
+#. Can be found by logging in to your Cloudflare account, click the site/zone, scroll down to the bottom.  
+#. You'll see it listed on the right side of the page.
 ZONE_ID="ZONE ID NUMBER HERE"
+
 #This can only be gotten by using the API to get a list of records for the zone.
-RECORD_ID="<RECORD ID NUMBER HERE"
+#  Reference: https://api.cloudflare.com/#dns-records-for-a-zone-list-dns-records
+RECORD_ID="RECORD ID NUMBER HERE"
+
 RECORD_NAME="example.com"
 RECORD_TYPE="A"
 TTL=1
@@ -13,18 +33,23 @@ TTL=1
 #Get the current IP address for the DNS record
 RECORD_IP="$(dig @1.1.1.1 $RECORD_NAME | grep $RECORD_NAME | grep -v ';' | awk '{ print $5} ')"
 
+# Get the current public IP address
 IP="$(curl -s http://ipinfo.io/ip 2> /dev/null)"
 
 DATE=$(date +%Y%m%d-%H%M%S)
 
 #If the RECORD_IP and IP do not match, then we need to update the record information.
 if [ "$RECORD_IP" != "$IP" ]; then
+
+        # Make the API call to update the DNS record and save the response details for confirmation of success/failure.
         RESPONSE=$(curl -s -X PUT "https://api.cloudflare.com/client/v4/zones/$ZONE_ID/dns_records/$RECORD_ID" \
                 -H "X-Auth-Email: $AUTH_EMAIL" \
                 -H "X-Auth-Key: $CLOUDFLARE_API_KEY" \
                 -H "Content-Type: application/json" \
                 --data '{"type":"$RECORD_TYPE","name":"'$RECORD_NAME'","content":"'$IP'","ttl":'$TTL'}')
         
+        # Output appropriate status details depending on whether or not the API call was successful or not
+        # If it failed, we want dump out the entire response for troubleshooting. 
         if [ $(echo "$RESPONSE" | grep '"success":true' | wc -l) -eq 1 ]; then
                 echo "$DATE|Record IP: $RECORD_IP|Pub IP: $IP|CF Update: Success"
         else
@@ -32,5 +57,7 @@ if [ "$RECORD_IP" != "$IP" ]; then
                 echo "Response: $RESPONSE"
         fi
 else
+        # The current public IP address matches the IP address for the DNS record.  
+        # There is nothing to do, yay!
         echo "$DATE|Record IP: $RECORD_IP|Pub IP: $IP|CF Update: Skipped"
 fi