Luiz Kowalski :: dev blog

Luiz Kowalski :: dev blog

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Latest — 01 Apr 2025

Double-click to submit form pattern with Stimulus (revisited)

Some months ago, I wrote about something I built, a component to submit forms with a double-click, where the user has to confirm the action, potentially avoiding miss-clicks and doing something irreversible by mistake Ever since then, I have evolved this component a bit, and I think it is in

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"Double-click to submit" pattern with Stimulus

While tinkering around with a home lab and CasaOS, I encountered this pattern where certain actions require a "double click", like this: I wanted to see how hard it was to copy this with Stimulus, and it turns out it is not that hard. Let's start

Traefik with Kamal: Tips and Tricks

It took me some time to finally figure out Traefik and some more time to put two and two together, so I'd like to share some things I learned on how to get it to work smoothly with Kamal. Traefik is a powerful and fun tool, but there

Production-Grade (ish) Rails deployment on Hetzner with Kamal

I've been toying around with Kamal for some time now, and I believe I have come up with a nice setup for a reasonably robust deployment. It includes two servers, one for the application and another for database and caching, a firewall to expose only the ports we

Taming complex Service Objects with dry-rb

As your Rails app grows, MVC feels inadequate. Should I put complex business rules in the models or the controllers? Should I just put everything in Concerns? At this point, most developers fall back to good'ol Service Objects: specialized classes with a single goal (register a user, send

Using concurrent-ruby in a Rails application

Concurrency in Ruby is still a gray zone for many developers. If you know anything about concurrency, you probably know that Ruby is thread-safe by default because the Global VM Lock only uses one thread and you are bounded by it. But does that mean that Ruby can't

Validating Mandrill webhook signature on Ruby on Rails

I'm writing this post partially because I couldn't find anything exactly like this and to keep a log for me, in case I have to deal with this once again. Since Mandrill does not provide a way to authenticate their webhooks using, for example, a user/

Encapsulation in Ruby on Rails

In Object-Oriented Programming, encapsulation is one of the fundamentals concept. Understand encapsulation will help you write concise and easy to maintain code. But what exactly is encapsulation? If you search on the Internet you might find something like this: encapsulation is hide the internal representation or state of an object.

A simple solution to scalability problems: Event Sourcing

In the past months I've been playing around with Kotlin and Spring's event sourcing engine. To get to know it better, I build a really simple clone of Untappd. If you don't know Untappd, a tl;dr is: Foursquare for beers. You can checkin

Deploying Spring Cloud Netflix apps on Kubernetes

If you are deploying containers on production, Kubernetes is a no-brainer solution. It takes some time to get familiar with all concepts but once you understand it, piece of cake 🍰. So today I wanna show you how to deploy an Eureka server, a Hystrix dashboard with Turbine and a microservice.