Rails 8.1 New API: `Rails.event.notify(...)`

Rails 8.1 is set to bring a new API, Rails.event.notify(...), that will help make it simple to publish structured events that are immediately consumable by monitoring and Application Performance Monitoring (APM) platforms like Datadog, AppSignal, New Relic, or Honeycomb.

In this post, we’ll look at how it works, why it matters, and how to prepare your app for data-hungry observability tools.

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Rails 8.1 Local CI as First-Class Support

DHH unveiled Rails 8.1 during his keynote at Rails World 2025, releasing the first beta live on stage. This new version brings a suite of tools aimed at making Rails apps simpler to build, maintain, and collaborate on. With a strong focus on developer experience and consistent workflows, Rails 8.1 helps teams sidestep common frustrations and work together more smoothly.

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The Forgotten Flag: How --trust-policy Works

Most of the times when we use the gem install command, we only ever need to pass it a few flags like the gem version or the path, in the case of a local gem. However, RubyGems has an often overlooked option that allows us to verify the authenticity and integrity of gems before installing them.

This flag that can quietly protect your system from running code you didn’t intend to trust. In this blog post, we’ll explore how RubyGems signing works, what the trust policy actually does, and why enabling it can make your gem installs far more secure.

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Why Fixed-Cost Maintenance Beats “As-Needed”

Maintaining a Ruby on Rails application often slips down the priority list. Everything seems fine, until suddenly it isn’t. A gem update breaks a feature, a security flaw makes headlines, or your app refuses to deploy after a server upgrade. When that happens, teams scramble to find help, often at the worst possible time. This “as-needed” upgrading approach may appear cost-effective in the short term, but it leads to stress, downtime, and unpredictable expenses.

But there is a smarter path forward: fixed-cost monthly maintenance opens a new window . In this post, you’ll see why investing in a maintenance retainer is better than reactive upgrades, and how our service delivers value month after month.

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Rails Versions You Shouldn't Be Using

Ruby on Rails has always moved at a steady, thoughtful pace: each new version brings not only features and performance improvements but also important security hardening. But with every release cycle, older versions reach the end of their lifespan. When a version is officially End-of-Life (EOL), it no longer receives bug fixes or security patches — leaving applications increasingly vulnerable as new threats emerge.

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Ruby 3.4.0 Released: What's New

Ruby 3.4.0 was released on December 25, 2024, bringing exciting new features, performance improvements, and some breaking changes. Here’s a practical guide of what’s new and what you should know before upgrading to this version.

Highlights

  • New it block parameter reference: Cleaner, more readable blocks using it instead of the original _1.
  • Language and core changes: Easier keyword argument handling, string literal warnings, reserved names, and updates to core classes.
  • Standard library updates: RubyGems, Bundler, JSON, Tempfile, and more get useful updates.
  • Compatibility and miscellaneous changes: New error message formats, hash and float handling, block and performance warnings, and deprecated features removed.
  • Prism is now the default parser: Ruby’s parser is now Prism, making it possible for better tooling and error messages.
  • Socket library upgrade: Happy Eyeballs v2 means faster, more reliable network connections out of the box.
  • YJIT and Modular GC: Advanced performance and memory improvements for those using Ruby’s JIT or experimenting with garbage collection.
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Rails and Ruby Compatibility in 2025

Rails 7.1 has been a dependable workhorse since its release in 2023. But on October 1, 2025, Rails 7.1.x will lose official security support opens a new window . That means no more patches for new vulnerabilities, no more backports, and no safety net if a zero-day exploit lands in your stack.

If you’re running Rails 7.1, your risk level depends heavily on which Ruby version you pair it with. Some Rails and Ruby combinations will be doubly unsupported after October 1st, creating “dangerous pairings” that should be upgraded immediately.

In this post, we’ll break down:

  • Which Ruby on Rails setups will lose support after October 1, 2025.
  • Why those combinations are risky.
  • How to quickly check your environment using our table below.
  • What to do if you are using a vulnerable pair.
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The Automated Roadmap to Upgrade Rails

The Roadmap to Upgrade Rails opens a new window is FastRuby.io’s discovery product that helps teams plan and execute their Rails upgrade projects.

We’re happy to introduce an Automated Version of the Roadmap, powered by an AI agent, available completely for free!

Check it out on the Automated Roadmap to Upgrade Rails opens a new window page and keep reading to learn more about how it works.

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Is It Ruby or Rails? Our New Discord Bot

At FastRuby.io, we spend our days deep in Rails codebases, upgrading, refactoring, and occasionally wondering, “Wait… is this method from Ruby or Rails?”.

Now, we’re turning that moment of confusion into a game. We’re excited to introduce Is It Ruby or Rails?, a brand new Discord bot that delivers daily puzzles to challenge your Ruby knowledge and fuel a little friendly competition.

You can install it using the Discord install link opens a new window and start playing right away!

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The Hidden Costs of Technical Debt in Rails

When people hear the phrase “technical debt”, they often picture broken code, outdated infrastructure, or a total rewrite waiting to happen. But in our experience at Planet Argon opens a new window , technical debt usually shows up more quietly.

It’s not a crisis. It’s a pattern.

It shows up in how long it takes to make changes, how often bugs sneak in, and how hesitant developers are to touch certain parts of the codebase. And while it rarely announces itself, it always costs something — whether in time, budget, or momentum.

In this post, we’ll highlight real-world examples of how technical debt has surfaced in Rails applications we’ve worked on. These aren’t horror stories — they’re common issues we see even in well-run projects. More importantly, we’ll share some ways teams can manage debt strategically without a massive rewrite.

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DIY Rails Upgrades: Open Source Tools

At FastRuby.io opens a new window , we deeply value the Ruby and Rails communities and believe in giving back through open source contributions. We wouldn’t be where we are today if it wasn’t thanks to a lot of open source projects we use on a daily basis.

We actively use, maintain, and enhance several tools designed to empower developers and teams who want to handle Ruby and Rails upgrades themselves, especially those who might not have the budget to hire our services.

These open source projects facilitate upgrades by improving transparency, managing technical debt, and ensuring smooth transitions between Ruby and Rails versions.

Here’s an overview of each tool and how it can support your next upgrade project.

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Check If a Gem Is Loaded in Your Bundler

Whether you’re debugging a dependency issue, checking for an optional gem, or just curious about what’s loaded in your Ruby app, there’s a handy command that can help:

puts Gem.loaded_specs.keys.grep(/your_pattern_here/)

In this article, we will discuss what this command does, what exactly it’s checking for, and its limitations.

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Extracting Rails Deprecation Warnings

At FastRuby.io opens a new window , we offer specialized Rails upgrade, maintenance, and technical debt services.

Before doing an upgrade, we strongly recommend doing the Roadmap to Upgrade Rails opens a new window , a static analysis of your codebase that outlines the action plan to do the upgrade and provides time and investment estimates.

The first step in every Rails upgrade we do is addressing deprecation warnings in the current version. So recently, we set out to extract all deprecation warnings from all versions of Rails starting at Rails 2.3 to help in our static analysis of Rails applications.

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Setting Up Rails with Dev Containers

Having reproducible development environments is one of the best ways to guarantee ease of application setup and code sharing in teams. Dev containers are a way to achieve this.

In this article we’ll try to give you a small introduction to what dev containers are at their core and provide a minimal example on how to set up a Rails application to use dev containers.

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