Ask HN: What is your favourite post on a company's internal tech architecture?

A lot of times one can find an insightful post on the internals of the architecture of a tech company. Some of the ones that I can remember are:

1. https://nickcraver.com/blog/2016/02/17/stack-overflow-the-architecture-2016-edition/

2. https://medium.com/@Pinterest_Engineering/sharding-pinterest-how-we-scaled-our-mysql-fleet-3f341e96ca6f

3. http://highscalability.com/blog/2012/2/13/tumblr-architecture-15-billion-page-views-a-month-and-harder.html

4. https://instagram-engineering.com/instagration-pt-2-scaling-our-infrastructure-to-multiple-data-centers-5745cbad7834

What is your favorite such post?