- Configuring the python client with a json string that did not seem to have a documented schema
- Error types that were overly general in some ways and overly specific in other ways
- HAProxy couldn't easily health check the service
There were a few others that I cant remember because it was ~5 years ago. I liked the idea of the contract and protobuf seemed easy to write but had no need for client side dns load balancing and the like and was not working in GoLang.