Hobby plan and auto scaling

I’m on the hobby plan. Im new to Fly.io. My concern is, am I on autoscaling? What happens if for some bizzarre reason my app gets DDOS or lots of demand, I don’t want to wake up one morning to a $10000 bill. Could that happen?

Could I perhaps set a max budget per month?

There is no auto-scaling by default. In general, most resources are allocated explicitly. One exception is outbound traffic (free limit is 30GB/month to certain regions).

If you get a surprise bill, contact billing@fly.io and they should refund you (ref).

If you want a stronger assurance, you can switch to prepaid credits and remove your credit card details. That’s the closest thing to a max budget.

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Newly-provisioned apps run on the Machines platform. The default config has auto_start_machines and auto_stop_machines set to true. This means your VMs will automatically scale to zero after a few minutes of no traffic, and will resume when traffic is detected. This will help save on costs to a certain extent. Also, autoscaling is not enabled by default so we wouldn’t automatically spin up new VMs unless it was configured to do so.

Regarding DDoS concern, it might be good to set up some WAF in front of your site, and the prepaid credit suggestion is solid as well.

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