The cheapest way to prevent an outage is to catch it early in its lifecycle. Software bugs are like real bugs. First is the egg, that's the idea of the change.

The cheapest way to prevent an outage is to catch it early in its lifecycle. Software bugs are like real bugs. First is the egg, that's the idea of the change. Then there's the nymph, when it hatches; first POC. By the time it hits production, it's an adult. Wait - isn't there a stage before adulthood? Yes! Your app should have several stages of maturity before it reaches adulthood. It's far cheaper to find that bug before it becomes fully grown (and starts laying its own eggs!) If you can't do canaries and rollbacks are problematic, add more testing before the production deploy. Linters, unit tests, end to end tests, profilers, synthetic monitors, read-only copies of production, performance tests, etc. Use as many ways as you can to find the bug early. Feature flags, backwards compatibility, and other methods are also useful. But nothing beats Shift Left.