[andrew_n]

Spot on. The metaphor I typically use here is cleaning up a mess vs spreading it around. If you have a really big mess and spend a year or two rearranging it into dozens or hundreds of smaller messes, yes the big obvious mess is gone, but the overall amount of mess has likely gone up and by segregating everything you’ve probably made it much harder to someday get to a clean state.

If you’re moving to microservices because the number of people working on a project is growing too large to manage and you need independent teams, great. If you’re refactoring to microservices because “we’re going to do everything right this time,” this is just big-rewrite-in-disguise.

Whatever engineering quality improvements you’re trying to make—tech stack modernization, test automation, extracting common components, improved reliability, better encapsulation—you’re probably a lot better off picking one problem at a time and tackling it directly, measuring progress and adjusting course, rather than expecting a microservices rewrite to magically solve a bunch of these problems all at once.

[jayd16]

>but the overall amount of mess has likely gone up

I don't think this is really the intuitive outcome. Think of cabinets, dressers, shelves etc. They're all basically little messes but they're much easier to deal with than one large mess.

[karmakaze]

Complexity (as in unintended/unexpected behaviour) varies with N^p where p > 1.0 so having N messages of 1/N size is a definite advantage and does make it easier to clean up the little messes.

[andrew_n]

It depends on what the messes are. Separating into different services adds significant overhead to addressing cross-cutting concerns.

If the modules of your system are already relatively independent with well-defined interfaces, microservices would be fine and yes would make changes like upgrading the language runtime version easier.

But when I think of messy, tangled, poorly-tested code that prompts people to start talking about needing to refactor to microservices, I’m thinking about different sorts of problems. The messiness I usually see has to do with lots of missing abstractions, lots of low-level code reading and writing directly to files and message buses and databases and datastores instead of going through some clean API. This makes it really hard to change things, because instead of updating some API backend, you have to find and update all the low-level accesses.

Now the problem is, typically when going to microservices, people aren’t looking at the question of, “What common stuff can we pull out to make all our messy code simpler?” They’re taking the existing, messy modules, with lots of cross-cutting shared abstractions dying to get out, calling the existing module a service, and putting a bigger barrier around it.

There are many ways to approach the problem of moving to cleaner, simpler abstractions, and microservices can help. But you can easily go to microservices without addressing all the needless complexity, instead crystallizing that complexity in the process, and many organizations end up doing exactly that.

[celticmusic]

that's assuming the complexity never crosses boundaries, which is why the whole mess analogy falls down.