I recently stumbled across a web-page from the guy whose professional bio is “wrote the backend billing code that 97% of Google’s revenue passes through.” He’s now an angel investor (a polite synonym for “rich”).
Since the Amazon outage, I've been wondering about the best way to quickly switch to another host.
This is exact problem we (Cedexis) solve.
Assume your site is www.website.com, in general points to an A record or a CNAME to a datacenter/ cloud/ CDN.
We add an intermediate hostname, low TTL (20 seconds), global anycast network, which can be scripted (write your load-balancing logic in php) to handout a CNAME (one of many) based on performance (RTT), load, cost, anything else you can think of, etc.
Re.: AWS's recent outage, assuming you are running your apps in multiple zones/ regions/ clouds, we would have noticed the latency and automatically routed away to a different zone/ region/ cloud.
Just so there is no ambiguity, we are alive, doing well and growing: https://duckduckgo.com/traffic.html