Why random selection is necessary to create stable meritocratic institutions (assemblingamerica.substack.com)

One of the reasons microservice architecture originally became popular was to break apart monolithic applications. In many cases, I bet a big driver was a lack of separation of concerns, and a more modular design was desired. There are many ways to put up walls in software to help make software more modular and self-contained. Rails engines are a good way to make more a rails app more modular. The number of times I've seen microservices created for the purpose of modularity (not scaling concerns), and the complexity that has brought has really soured me on microservices.

giovapanasiti · 3h ago

This is exactly my experience. Most of the time people go to microservices for the wrong reason and they will regret that for years

whstl · 3h ago

Different sections of an app can use different databases, if the bottleneck is in the database.

Different routes can be served by different servers, if the bottleneck is in CPU usage.

Different async tasks can run on different task runner services, if the problem is tasks competing with each other.

Different test suites can run for different sections of the app, if the problem is with tests taking too long to run.

Github and others even allow specific subfolders to be "owned" by different teams.

What else is there? Even slowness of compilation and/or initialization can be alleviated, depending on the language or framework.

stronglikedan · 2h ago

I think the point is that all of that adds complexity that is often unnecessary - a premature optimization if you will. It's like a hammer, and everything looks like a nail to a lot of people.

inopinatus · 1h ago

GP isn’t oppositional, they listed runtime constructs that all run off a single monolith. The point being you don’t need so-called microservices for flexibility in the production environment.

leptons · 2h ago

I've built numerous systems on AWS Lambda over the last 10 years, and have never once regretted it. YMMV.

ecshafer · 1h ago

Ive regretted 99% of the services Ive built in AWS lambda over the years. Everytime it gets more complex than a couple hundred lines of code over a few lambas I start to think “if this were just one service, development, deployments, cicd, testing, storage would all be simpler”.

nurettin · 3h ago

I use multiple services for resilience. Example: With multiple services that have clear separation of concerns, you can debug and fix your processing layer without stopping the collection layer. You can update a distributor while workers wait and vice versa. This way I never have downtime anxiety. No regrets.

zrail · 2h ago

Separation of services is orthogonal to separation of concerns. There's nothing stopping you from having multiple entry points into the same monolith. I.e. web servers run `puma` and workers run `sidekiq` but both are running the same codebase. This is, in fact, the way that every production Rails app that I've worked with is structured in terms of services.

Concerns (in the broad sense, not ActiveSupport::Concern) can be separated any number of ways. The important part is delineating and formalizing the boundaries between them. For example, a worker running in Puma might instantiate and call three or four or a dozen different service objects all within different engines to accomplish what it needs, but all of that runs in the same Sidekiq thread.

Inserting HTTP or gRPC requests between layers might enforce clean logical boundaries but often what you end up with is a distributed ball of mud that is harder to reason about than a single codebase.

mrinterweb · 2h ago

For your example, rails apps handle this case by default with job queues that are managed by the deployment separately. There is a way to force the job queue to process in the same process as your web server, but that's not the way most should be running prod rails apps. There usually isn't anxiety associated with rails app deploys, in my experience.

rco8786 · 2h ago

What can you not do in a monolith? You can still have async queues and different event processors that stop and start independently within a monolithic deployment.

JohnBooty · 1h ago

Speaking as a monolith fan, IMO/IME the main drawback is RAM usage per instance.

You can have a "big, beautiful" Rails monolith codebase used by both Puma and Sidekiq queues etc, and that works well from most standpoints. But RAM usage will be pretty high and limit horizontal scaling.

helle253 · 5h ago

I love Rails Engines, it's a very slick feature.

I recently migrated a featureset from one Rails project into another, as a mounted engine, and ensuring isolation (but not requiring it!) has been tremendously helpful.

capevace · 4h ago

The Filament package for Laravel lets you build similarly encapsulated „plugins“, that are basically mini Laravel apps, that can be easily added to existing apps.

The plugins can rely on all of the Laravelisms (auth, storage etc) and Filament allows them to easily draw app/admin UI.

malkosta · 2h ago

Offset-based pagination will be a problem on big tables.

hk1337 · 5h ago

I have been looking at using Rails Engines recently playing around with trying to get an idea off the ground.

GGO · 4h ago

Rails engines are one of the most underrated features that everyone should be using more.

matltc · 4h ago

Miss seeing rails in the wild

pqdbr · 3h ago

Rails is not only alive and well, but actually booming.

Octoth0rpe · 1h ago

> Rails is not only alive and well, but actually booming.

Do you have any references that validate this?

Rails 'booming' on a 3 year time scale wouldn't surprise me, but would on a 10 year scale.

henning · 5h ago

This blog post just shows how libraries and frameworks often solve one problem but create another. This leads to the emission of ridiculous sentences like `One of the trickiest aspects of building engines is handling routing correctly` which would be a non-issue if you just wrote simple code to solve the problem in front of you instead of doing a bunch of "modular" "engine" framework-y compiler-y nonsense that adds boatloads of complexity just to accomplish one basic thing like handling file uploads.

adenta · 5h ago

What problem was created?

pqdbr · 3h ago

"one basic thing like handling file uploads" - say no more.

Actually, the article isn't even about handling file uploads - it's about deliberately creating a modular admin panel for dealing with file uploads.

It's not modularity for "framework-y" sake, but to easily deploy that admin panel in other applications with literally a one-liner.

giovapanasiti · 3h ago

I couldn't have written this comment better myself. Thank you this is exactly the point

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Building Modular Rails Applications: A Deep Dive into Rails Engines

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