What is a reliable software?

Reliable means a lot of things, for commerce it is SLA (Service Level Agreement) that companies are obligated to provide a certain level of reliability and compensate customers if this agreement is broken. If a user cannot access the system, it is – from the user's point of view – unavailable.

For solo devs that are rolling up some APIs means that your API should successfully respond to 99.99% of well-formed request, or often referred as "four nines of availability".

You might think it is reasonable thing to do, but put it in perspective you can only afford up to 52 minutes of downtime throughout a whole year.

Achieving four nines of availability is tough. Choose your VPSs correctly and write better containerization.