(Source link in parent post, emphasis mine).
In this case they had a additional cost due to delay of $72k. Which, lets be honest means this feature kinda useless for anything but the somewhat harmless case.
Only by combining this with resource limits in load balancers, instance and concurrency limits and similar can the maximal worst cost be limited. But tbh. this partially cripples auto-scaling functionality and it's really hard to find a good setting which doesn't allow to much "over" cost and at the same time doesn't hinder the intended auto-scaling use-case.
> I created a new GCP project ANC-AI Dev, set up $7 Cloud Billing budget, kept Firebase Project on the Free (Spark) plan.
There's a lot of middle ground between $7 and $72k. Your quote explains it perfectly though. They flat out can't because the accounting and reporting is badly designed and incapable of providing (near) real-time data.
IMHO the easiest solution to this is government regulation. If you set a budget for a pay-what-you-use online service there should be legislation forbidding companies from charging you more than that.
I also find it (sort of) hilarious they can magically lock the whole thing down once payment fails, but not before the CC is (presumably) maxed out. Lol. Talk about a good deal for Google.
Unfortunately for all of us, your solution doesn't work, per the huge disclaimer on the page that says those alerts can be days late. You can rack up an almost unlimited $ bill in hours.
Literally did this my first week when trying out GCP for my company. It is entirely possible and documented (with code):
https://cloud.google.com/billing/docs/how-to/notify#cap_disa...