To make up an example that doesn't depend on any of those things: imagine that I've added a new feature to Hacker News that allows users to display profile pictures next to their comments. Of course, we have built everything around microservices, so this is implemented by the frontend page generator making a call to the profile service, which does a lookup and responds with the image location. As part of the launch plan, I document the "big red button" procedure to follow if my new component is overloading the profile service or image repository: run this command to rate-limit my service's outgoing requests at the network layer (probably to 0 in an emergency). It will fail its lookups and the page generator is designed to gracefully degrade by continuing to render the comment text, sans profile photo.
(Before anyone hits send on that "what a stupid way to do X" reply, please note that this is not an actual design doc, I'm not giving advice on how to build anything, it's just a crayon drawing to illustrate a point)
To make up an example that doesn't depend on any of those things: imagine that I've added a new feature to Hacker News that allows users to display profile pictures next to their comments. Of course, we have built everything around microservices, so this is implemented by the frontend page generator making a call to the profile service, which does a lookup and responds with the image location. As part of the launch plan, I document the "big red button" procedure to follow if my new component is overloading the profile service or image repository: run this command to rate-limit my service's outgoing requests at the network layer (probably to 0 in an emergency). It will fail its lookups and the page generator is designed to gracefully degrade by continuing to render the comment text, sans profile photo.
(Before anyone hits send on that "what a stupid way to do X" reply, please note that this is not an actual design doc, I'm not giving advice on how to build anything, it's just a crayon drawing to illustrate a point)