Ask HN: How to host simple Rails API to get 99.99% uptime

Actually, https://controlplane.com provides 99.999% availability SLA. The reason it is able to do so is because it distributes your containerized workloads across multiple regions on multiple clouds (you pick the regions and clouds). You can have a single region or 200 regions - with the same effort. It then charges you by the millicore (1,000th of a vCPU core) for exactly what your app uses. It gives you metrics, logging, tracing, alerting, secrets management, service discovery, auto-TLS and you can trivially use your own domain name. You get the power of the hyper-scalers with the ease of use of Heroku. The best part is that it lets you mix-n-match ALL/ANY service from any cloud in your code without you having to deal with credentials! Meaning you can use S3, DynamoDB, RDS, Big Query, Big Table, Cosmos DB, etc. - across AWS, GCP and Azure and you can even run your code on-premises or on ANY providers such as Linode, Hetzner, Contabo, Equinix, Oracle, etc. In short - it is the "non-toy" way to run your code when failure is not an option, but at a ridiculously low cost.

I love my own little "devops" toolkit to get this on google cloud and all for free if you stay in their free tier:

https://many.pw/hosting

You get a 30GB hard drive, 1GB ram, and two AMD EPYC 7B12 2250 MHz processors. That's enough to run a nice little site with plently of traffic.

To keep uptime during deploys it runs a reverse proxy to port 3000 and 3001 and switch between them each deploy.

Most cloud services have SLAs of 99.99 themselves, so it's not entirely realistic to go higher than that.

The good news is that you probably don't need 99.99. Read "Embracing Risk": https://sre.google/sre-book/embracing-risk/

Use https://controlplane.com - you'll get multiple regions and ultra low cost and fun user experience.