When to adopt the microservice architecture

Microservices should primarily be considered for systems in which managing the traditional monolithic application has become too complex to develop and maintain. If you are developing a small application, additional complexity, described in the preceding paragraph, may outweigh the modularity benefits and inhibit, instead of amplifying, your development process.

It has been suggested (Further Reading, link 3) that microservices architecture should be an evolution of the monolith application. Most systems should start as a monolith, and the transition to microservices should only be considered when the system grows to the extent that it becomes too hard to develop and maintain.

Last but not least, if the system is badly designed, the transition to microservices won't magically solve its problems. To put it more bluntly, distributing a messy system will result in an even greater mess. As we have already mentioned, microservices should be considered as a solution when the complexity of the system requires imposing modularity and not as a magical fix for badly written software.