I am currently working on a set of microservices. The initial design made sense.

A small microservice stood outside a monolith. It was triggered by webhooks from a 3rd party service. It had a service inside the monolith that provided it the required data.

This provided isolation so that the third party had no direct communication route with the main application.

A few months later and more features have been added. We now use a form inside the monolith to capture the data equivalent that the third party sent.

Moving the data around to perform the calculations in the small microservice is becoming increadingly complex. Once we capture all the data with the new form the small microservice now has no reason to exist.

This is a concept that is hard to track if you have a large amount of microservices. How do you know that a given microservice still needs to exist? This is frequently not documented well.

This concept repeats at other levels. Why does a given function exist? Without continous pruning you end up maintaining dead code.

The only answer is for each service to have a sponsor to keep it alive. If the sponsor is removed find another or remove the item.