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I think lots of microservices can be replaced with a monolith which in turn can be replaced with a set of composable libraries versioned separately.

If anyone doubts that, this very browser used to read and write is built all the way up with dozens of libraries from compression, network, image encoding, decoding, video encoding decoding, encryption, graphics, sound and what not where each library is totally separate and sometimes was never intended to be used to build web browsers by the original authors.

Rest assured, most of the business (or web 2.0 systems, search, curate, recommend, surface etc kind of) systems are a lot more simpler then an A class browser.

If you are using Chrome, it's also a combination of multiple well separated processes talking via RPC with each other, which is pretty similar to microservices, although the separation boundaries are more influenced by attack mitigation requirements than your typical microservice architecture would be.

And even that process separation is spinning up more processes from within the same binary or build artefact. The usual fork() and CreateProcessW() etc and then wait on them.

Unlike in Microservices where each process is possibly a totally different language, runtime and framework spun up individually that too possibly in totally different ways.

But that’s due to security, not for any supposed benefit of microservices. Also, both processes are from the same repo sharing code, so I wouldn’t really qualify as microservice.

1. microservices also create security boundaries

2. microservices living in monorepos is common

That‘s literally an example of the decision depending on multiple factors. Separation of concerns -> more isolation -> stronger security of the overall system is exactly one of the possible benefits of microservices.

Scale is just one. There is also fault tolerance, security, organizational separation (which can be, up to a point, also be realized with libraries as you suggest), bigger ecosystem to choose from, …

These blanked statements about monoliths are what made every junior dev think that microservices are the only solution.

If you cannot make a clean monolith, I have never seen any evidence that the same team can make good microservices. It is just the same crap, but distributed.

The last 2 years I see more and more seasoned devs who think the opposite: monoliths are better for most projects.

> It is just the same crap, but distributed.

Yes, but also - more difficult to refactor, more difficult to debug (good luck tracking a business transaction over multiple async services), slower with network overhead, lack of ACID transactions... Microservices solve problems which few projects have, but adds a huge amount of complexity.

monoliths are the postgres of architectures - keep it simple until you really can't, not until you think you can't.

In my experience, the biggest issue with microservices is that they convert nice errors with a stack trace to network errors. Unless you also invest heavily in observability (usually using expensive tools), running and debugging monoliths generally seems easier

Microservices necessarily add more complexity and overhead when compared to a monolith. Just the fact that you have to orchestrate N services instead of just pressing run on a single project demonstrates some of the additional complexity.

Counterpoint: a monolith usually contains a complex init system which allows multiple ways of running the codebase. Microservices can avoid at least that one complexity.

Another advantage of microservices is that you can avoid the overhead of multiple services by having one really big microservice.

You mean like profiles? Monolith can run like a front service or background worker depending on the config?

In a technical sense it is a complexity, but IME pales in comparison with the alternative of having to manage multiple services.

I actually really like this model, it's pretty flexible. You can still have specialized server instances dedicated for certain tasks, but you have one codebase. What's very sweet is that for local development, you just run a single application which (with all enabled profiles) can fulfill all the roles at the same time.

Thanks no. I rather wait 10ms for a rebuild and 1s on gdb init, than 25m for a monolith rebuild, and 2m on gdb init.

Seperate processes, yes.

Who says monoliths don't have clear and explicit separation of concern between domain concerns? I think that just comes down to how the codebase is organized and how disciplined the team is, or possibly breaking out core parts into separate libraries or other similar strategies - technically it's still a monolith.

Libraries are a great way to manage separation of concerns. Any dependency you add has to be explicit. There's nothing stopping you from adding that dependency but you can't just do it accidentally.

The graph of dependencies between components makes for explicit separation of concerns just like you would have a graph of dependencies between different network services.

Or you just use a language with support for clear module API boundaries (vs something like Ruby where without bolt on hacks, every piece of code can call any other in the same process).

The lower cost of a function call versus any microservice network call is a good performance advantage of a monolith. Monoliths also make refactoring code a lot easier. While in theory I agree about the spaghetti issue, in practice I haven't seen much of a difference. In part because microservices seem to encourage proactive overdesigning, and then the designs don't age well.

I also find monoliths a lot easier to debug. You have the whole call stack, and you get rid of a lot of potential sources of latency problems. You don't have RPC calls that might sometimes get forgotten.

Given the choice, I'd choose monolith every time. Unless, of course, microservices are needed for various other reasons. (Scale, the ability to distribute, etc.)

> In my experience monoliths don't reduce complexity, they just shift it

This is both true and false in a way. Sure, the same business logic is distributed across microservices, but a method call in a monolith can only fail in a couple of ways, while network calls are much more finicky - handling it in every case is pure added complexity in case of a microservice architecture.

Also, don’t forget the observability part - a mainstream language will likely have a sane debugger, profiler, a single log stream, etc. I can easily find bugs, race conditions, slow code paths in a monolith. It’s much more difficult if you have to do it in a whole environment communicating with potentially multiple instances of a single, or multiple microservices.

Lastly, we have programming languages to help us write correct, maintainable code! A monolith != spaghetti code. We have language tools to enforce boundaries, we have static analysis, etc. A refactor will work correctly across the whole codebase. We have nothing of this sort for microservices. You might understand a given microservice better, but does anyone understand the whole graph of them? Sure, monoliths might become spaghettis, but microservices can become spaghettis that are tangled with other plates of spaghettis.

Microservices also introduce the issue of maintaining schema compatibility for messages between services which usually leads to additional code in order to maintain backward compatibility

From a technical POV they are good for horizontally scaling different workloads which have a different resource footprint

From my experience, when a company decides to go the microservice route, it's more for the sake of solving an organizational problem (e.g. making team responsibilities and oncall escalation more clear cut) than it is to solve a technical problem. Sometimes they will retroactively cite the technical benefit as the reason for using them, but it feels like more of an afterthought

But in all honesty: microservices are very good at solving this organizational problem. If microservice x breaks, ping line manager y who manages it. Very straightforward

This presupposes that there is more than one line manager.

I see people trying to apply micro services architectures to a web app with a single developer.

As in literally taking a working monolith written by one person and having that one person split it up into tiny services.

It’s madness.

If your goal is to learn kubernetes instead of developing a product, then go for it IMHO, no better way. Just make sure everyone is on board with the idea.

I call this customer-funded self-training.

You could do that with code owners file in a monolith as well.

>My favourite thing about microservice architecture is how simple individual microservices are to understand and contribute to.

I generally agree with your stance and I would add that I find the whole simplistic „microservices suck“ talking point as nonsensical as viewing them as a panacea. They do solve a few specific (for most companies, mostly organizational/human factors because scale and redundancy don’t matter that much) problems that are harder to solve with monoliths.

I still think this point is a bit misleading, because yes, the components become simpler, but their interaction becomes more complex and that complexity is now less apparent. See:

>The architecture and provisioning of microservices can be more complicated, but from the perspective of a developer working on a microservice it should be much simpler to work on compared to a monolith.

I think that perspective often doesn’t match reality. Maybe most microservice domains I‘ve seen had poorly separated domains, but changes small enough to ignore the interactions with other services have been rare in my experience.

Amazing this was downvoted. The comment starts with "in my experience" and is hardly a controversial perspective. I beg the HN community, stop disincentivizing people from respectively providing a converse opinion, lest this become yet another echo chamber of groupthink.

It's because it didn't loop back to queues at any point. It's just a tangent on a tired topic.

We've swung back and it's trendy to hate on microservices now, so join in! /s

Patiently waiting for common sense to be fashionable. Alas, sensible people are too busy to advocate on the internet.

It relates that there was experience, but not what that experience was - We can read and understand that they're reporting their own experience, but that's about it.

One could say "In my experience, the earth is flat", but there's not much a conversation to be had there.

One could say, "In my experience, the earth is flat - I got in my car, went for a drive in one direction, and eventually hit a cliff at the ocean instead of finding myself back where I started". Now there's something to talk about.

(To be clear: this is the internet, and a limited communication medium: I'd assume OP could relate details about their experience, and it's totally reasonable that instead of taking the time to do that, they went outside and touched grass)

That’s not a reason to downvote. Downvoting is a censorship tool.

> My favourite thing about microservice architecture is how simple individual microservices are to understand and contribute to.

Whether this is good depends on the type of changes you need to make. Just as you mentioned maintaining modularity in a monolith can be difficult with entropy tending to push the code to spaghetti, there is an equivalent risk in microservices where developers duplicate code or hack around things locally versus making the effort to change the interfaces between microservices where it would make sense.

Ultimately microservices add structure that may be useful for large enough teams, but is still overhead that has to earn its keep.

> My favourite thing about microservice architecture is how simple individual microservices are to understand and contribute to.

You can achieve exactly the same with simple individual libraries.

"Cleverness, like complexity, is inevitable. The trick is making sure you're getting something worthwhile in exchange."