My AWS monthly bill is normally less that $10 (USD, before taxes), of which the t2.micro server is about 55%, EBS storage another 44%, and the remaining 1% is email and S3 usage. The August bill was over $21, with the AWS Web Access Firewall (WAF) being 55% of the total. I had originally enabled WAF on all my CloudFront distributions since the CloudFront configuration suggested that the cost would be $14/10 million requests per month, which based on the websites I had migrated would be an insignificant cost.
On August 15, I received an AWS billing alert that my next bill would exceed $20. Further investigation revealed that in addition to the usage charge, each WAF rule costs $1 and each WAF Web ACL costs $5 (monthly, pro-rated hourly). I disabled all CloudFront WAF rules but it was difficult to confirm that this would stop the additional charges.
The detailed usage logging that I set up when I started with AWS showed line items for each WAF component but with a start date of August 1 and and end date of August 31. The Usage Quantity was hard to interpret since it covers both the number of rules and the duration that the rules were active. I followed the instructions in https://docs.aws.amazon.com/waf/latest/developerguide/web-acl-deleting.html - there were no Web ACLs defined. A response to https://repost.aws/questions/QUS0kSuMVDQpaocRGzWi0Khg/how-to-stop-waf-charging-me-please suggested checking "WAF & Shield/Rule groups" - again, nothing defined. The AWS Cost Explorer did show a dramatic reduction in the daily costs, so the AWS Serverless component of my next bill should be well below Bernie Michalik's How to set up a static website for about $1 a month that originally got me started with AWS Serverless.
The good news is that the AWS SSL certificates generated for CloudFront are (so far) free. I have been using Let's Encrypt certificates that are free but need to be renewed every 90 days. In the past, the renewals were automatic but recently I have been running into issues that I have not yet been able to diagnose and resolve.
Blog comments2
Thanks for sharing this,…
Thanks for sharing this, Norbert! I am surprised the WAF rules cost so much relatively speaking. It will be interesting to see what your costs eventually land on.
September AWS Invoice
September is back to normal, with under U$10 (before tax) charges with the same distribution of t2.micro server (55%), EBS storage (44%), and S3 (1%). My S3 storage costs have gone up a bit but as a result of email pricing changes, my email costs were zero. My AWS Serverless hosting of five small and relatively quiet sites added about U$0.09 to my invoice. I will need to keep an eye on log file storage which can quietly add up.