I'm a big fan of Go and we use it internally, but I too wonder why nginx + Lua wouldn't be the chosen path.
If it's good enough for Cloudflare it probably is good enough here.
Besides, Varnish also would have excelled (yes I read the first post in the series) if they had just stored the configuration in a saner format and then output the required VCL when the config changed and reloaded on the fly.
Both of the technologies I would've picked (nginx and Varnish) were in their stack.
I love working in Go, but reading this feels like a reinvention of the wheel. Go would be my choice only if these other things didn't exist already and you had to start from scratch.
The biggest pain identified was the writing, maintaining and loading of the router config. Openresty could've solved that.
Openresty and Lua are great, but Go is a more generally applicable language for building web services. So when taken in that context Go makes more sense if we look at it as a learning exercise as well as a new part of the stack.
