9.5 Hard budget breakers and runaway protection
A mistake of yours cannot produce a bill you cannot pay.
Before:01. Cloud Foundations
A student mistake must not produce a bill a student cannot pay, and this topic installs the guarantees: hard caps and quotas, automated shutdown, and knowledge of the classic runaways — recursive functions calling themselves, forgotten GPUs, open egress. It closes the cost module because it is the safety net under all the practice. The confusion it corrects is trusting alerts alone; an alert at midnight that is read at breakfast has already cost eight hours, which is why the cap, not the alert, is the actual protection.
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The classic runaways: recursive functions, forgotten GPUs, open egress
The known ways to generate an enormous bill by accident are a function that triggers itself, a graphics instance nobody stopped, and data pouring out unnoticed. Recognising the list is most of avoiding it.
Hard caps, quotas and automated shutdown
Quotas and automatic shutdowns are the controls that hold when attention fails, which is exactly when they are needed. Setting them is unglamorous and it is what makes experimenting safe.
Free-tier limits and what happens when you cross one
Free-tier allowances end, and what happens at the boundary differs by service: some stop, some start charging quietly. Knowing which is which for what you use prevents the classic first surprise.
Degrading gracefully when a budget is hit
When a limit is reached, stopping the expensive part while keeping the service partly alive is better than an abrupt halt. Deciding what degrades first is a design choice worth making in advance.
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