How Can I Avoid an AWS Bill Shock Like This?

Make sure you set up billing alerts when you create your AWS account. These alerts can notify you about unexpected usage. There are also cost anomaly monitoring tools that can help catch unusual spending patterns in real-time, which could prevent scenarios like yours.

I’ve been there too! To prevent runaway spending, I use API Gateway to invoke my Lambda functions instead of exposing them directly. This allows me to set usage limits so if calls exceed a reasonable rate, they just get blocked. It's a great way to minimize costs and AWS support confirmed that failed requests over the rate limit won't be billed, which is a major plus!

Setting up alarms and a kill switch can be super effective. You can trigger a backup function that removes permissions from the offending Lambda if it hits a certain threshold. It’s just a good practice to keep your resources from running away with too much usage.

Lambdas have built-in recursion guardrails that terminate after 16 invocations. You should look into setting reserved concurrency limits to cap how many instances can run. Additionally, monitoring your Lambda executions right after deployment can help catch any runaway processes. But honestly, a prepayment option that freezes resources after exceeding a limit would be a game changer for us all.

You might consider researching options like setting a cost limit in your AWS account settings. Although they really only allow alerts, having something that shuts down services once spending exceeds a certain limit would definitely help avoid these situations.