On Rails

In this episode of On Rails, Robby is joined by Simone Carletti, CTO of DNSimple, where Rails has sat at the core of a globally distributed DNS platform since the company launched in 2010. Simone walks through how DNSimple's infrastructure is organized across three primary languages - Ruby on Rails, Go, and Erlang - each chosen deliberately for the role it plays: Rails powering the main application and API, Go handling the zone server, and Erlang running their custom-built name servers. He explains why Rails has remained central even as the platform grew well beyond a typical web app, and what it takes to keep a long-lived codebase healthy with a lean team of around 15 engineers.

Tools & Libraries Mentioned

Sidekiq: Background job processing (enterprise edition).

RSpec: Testing framework.

Knapsack: Parallel test suite splitting.

Lograge: Structured JSON logging for Rails.

ViewComponent: Component-based view layer for Rails.

Hanami: Ruby web framework, used for portions of the DNSimple API.

PostgreSQL: Primary relational database.

ClickHouse: Analytics database for DNS query log processing.

Erlang/OTP: Runtime for DNSimple's custom name server (ErlyDNS).

Go: Language powering DNSimple's zone server.

Docker / Docker Compose: Used to run the full DNSimple infrastructure stack locally.

Cursor / Claude Code: AI coding tools adopted across the DNSimple team.

Terraform / Infrastructure as Code: Used to manage DNSimple's own domains and GitHub repositories.

Books Mentioned

Eloquent Ruby by Russ Olsen

Design Patterns (Gang of Four)

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On Rails is a podcast focused on real-world technical decision-making, exploring how teams are scaling, architecting, and solving complex challenges with Rails. 

On Rails is brought to you by The Rails Foundation, and hosted by Robby Russell of Planet Argon, a consultancy that helps teams modernize their Ruby on Rails applications.

In this episode of On Rails, Robby is joined by Jay Tennier, Engineering Manager at Rainforest QA, where he's spent over seven years working across a long-lived Rails monolith and supporting services. They explore how Rainforest maintains their platform with a small team, and the practical decisions that come with that reality. Jay shares lessons from pulling microservices back into the monolith, why they wrap third-party services in adapters, and how they push analytics work to BigQuery instead of straining their Rails database. The conversation covers testing philosophy including "wet tests" over DRY abstractions, using dry-monads for complex service flows, and how celebrating code deletion has become part of their engineering culture.

Social + Web Presence

LinkedIn: https://www.linkedin.com/in/jaytennier/
GitHub: https://github.com/jaytennie/ 

Twitter/X: https://x.com/jaytennier
Bluesky: https://bsky.app/profile/jaytennier.bsky.social

Company/Org Links

Homepage: https://www.rainforestqa.com/

Tools & Libraries Mentioned
Active Record: Rails ORM.  

BigQuery: Hosted analytics warehouse.  

Cube.js: API layer for querying analytics data.  

DRY-Monads: Structured success/failure flow.  

FactoryBot: Test data factories.  

Grape: Ruby API framework.

GoodJob: Background job processor.  

Q Classic: DB-backed job queue.   

Redash: SQL-based dashboards and reporting.  

RSpec: Rails testing framework.  

React: Front-end application framework.  

Haml: Legacy templating engine.  

Segment / Mixpanel: Event tracking pipelines.

Books Mentioned

Confident Ruby by Avdi Grimm  

Exceptional Ruby by Avdi Grimm  

Working Effectively with Legacy Code by Michael Feathers 

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On Rails is a podcast focused on real-world technical decision-making, exploring how teams are scaling, architecting, and solving complex challenges with Rails. 

On Rails is brought to you by The Rails Foundation, and hosted by Robby Russell of Planet Argon, a consultancy that helps teams modernize their Ruby on Rails applications.

In this episode of On Rails, Robby is joined by Kayla Reopelle, a lead software engineer at New Relic, where she works on both the Ruby Agent and OpenTelemetry RubyGems. They explore what observability means for Rails developers—not just as a debugging tool, but as a way to build clearer, more reliable systems. Kayla explains OpenTelemetry's vendor-agnostic approach to instrumentation and shares practical ways to experiment with traces, metrics, and logs in both production and local development.

GitHub: https://github.com/kaylareopelle 

🧰 Tools & Libraries Mentioned

ActiveSupport::Notifications: Rails’ pub/sub API used for instrumentation.
AppSignal: Rails-friendly APM and error tracking.
AWS X-Ray: Distributed tracing for AWS services.
Datadog: Full-stack observability platform.
Elastics Profiling Spec: Donated profiling format for OpenTelemetry.
Grafana: Open-source dashboards and visualization.
Honeybadger : Error monitoring for Ruby apps.
Jaeger: Distributed tracing system (CNCF).
New Relic Ruby Agent: APM agent for Ruby and Rails.
ObservableGauge (OTel Metrics): Async gauge for snapshots like queue size.
OpenTelemetry Collector: Pipeline for receiving and exporting telemetry data.
OpenTelemetry Logger Bridge: Sends Ruby logger output to OTEL.
OpenTelemetry Ruby: Vendor-agnostic telemetry for Ruby.
OpenTelemetry Ruby SIG: Community group maintaining OTEL Ruby.
Prometheus: Metrics collection and storage.
Rack Middleware: Web middleware stack used in many Rails instrumentations.
Rails Structured Logging / Event Reporter: Structured logs built into Rails.
Semantic Logger: Structured logging for Ruby & Rails.
Stripe Ruby Gem: Payments client used as an instrumentation analogy.
UpDownCounter (OTel Metrics): Counter for tracking active jobs.

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On Rails is a podcast focused on real-world technical decision-making, exploring how teams are scaling, architecting, and solving complex challenges with Rails. 

On Rails is brought to you by The Rails Foundation, and hosted by Robby Russell of Planet Argon, a consultancy that helps teams modernize their Ruby on Rails applications.

In this episode of On Rails, Robby is joined by Miguel Conde and Peter Compernolle from Gusto, where they work on a "biolith"—two distinct Rails monoliths serving 600+ engineers. Peter leads the HIPAA-compliant benefits domain, while Miguel is extracting the time product from the main monolith. They explore how Gusto identifies boundaries, manages temporal data, handles eventual consistency, and navigates the trade-offs of GraphQL federation.

🧰 Tools & Libraries Mentioned

ActiveAdmin: Admin UI for Rails.

after_commit_everywhere: Run code after commits.

Datadog: App and CI/CD observability.

FactoryBot: Build test data.

GraphQL: API layer for SPAs.

Kafka: Event streaming backbone.

Packwerk: Enforce boundaries in monoliths.

PaperTrail: Model change auditing.

React: Front-end framework.

Sidekiq: Background job processing.

Sorbet: Gradual Ruby types.

TypeScript: Typed JavaScript.

explicit_activerecord: Guard writes to models.

Ruby Koans: Learn Ruby by practice.

Cracking the Coding Interview: Interview prep book.

Gusto Engineering Blog: Posts from Gusto engineers.

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On Rails is a podcast focused on real-world technical decision-making, exploring how teams are scaling, architecting, and solving complex challenges with Rails. 

On Rails is brought to you by The Rails Foundation, and hosted by Robby Russell of Planet Argon, a consultancy that helps teams modernize their Ruby on Rails applications.

In this episode of On Rails, Robby is joined by Alexander Stathis, a Principal Software Engineer at AngelList, where Rails powers complex investment, accounting, and banking business logic across a modular monolith structure. They explore how AngelList maintains conceptual boundaries in their codebase, uses gradual typing to influence their Ruby style away from Rails “magic,” and why they’ve adopted multiple async job solutions for different types of work rather than seeking a one-size-fits-all approach. Alex shares insights on consolidating microservices back into their monolith, creating the Boba gem to extend type generation capabilities, using production data subsetting tools for local development, and successfully onboarding engineers without Rails experience in under a month while staying current on Ruby 3.4 and Rails 7.2.

Tools & Libraries Mentioned

Active Job – Framework-agnostic job API built into Rails.

ASDF – Tool version manager.

Boba – AngelList’s Sorbet compiler extension.

Delayed Job – Database-backed job processor.

FactoryBot – Test data builder.

GoodJob – Postgres-backed Active Job processor.

GraphQL Batch Loader – Batching utility for GraphQL.

GraphQL Ruby – Ruby GraphQL implementation.

Linear – Issue tracking tool.

Money – currency handling library.

Packwerk – Shopify’s modular boundary enforcement tool.

Paperclip – Legacy file attachment gem for Rails (deprecated).

RSpec – Ruby testing framework.

Sidekiq – Redis-backed job framework.

Solid Queue – Rails 8 Active Job adapter.

Sorbet – Gradual static type checker for Ruby.

State Machines – Finite state machine support.

Tapioca – Sorbet RBI file generator.

Temporal – Workflow orchestration system.

Tonic – De-identified datasets platform.

Will Larson – Staff Engineer – Book exploring technical leadership

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On Rails is a podcast focused on real-world technical decision-making, exploring how teams are scaling, architecting, and solving complex challenges with Rails. 

On Rails is brought to you by The Rails Foundation, and hosted by Robby Russell of Planet Argon, a consultancy that helps teams modernize their Ruby on Rails applications.

In this episode of On Rails, Robby is joined by Florent Beaurain, a longtime Rails engineer at Doctolib, home to one of the largest Rails monoliths in Europe with over 3 million lines of code and 400+ engineers. They explore how Doctolib’s team tackled massive test suite performance issues, including cutting one engine’s test time from seven minutes to under one minute. Florent shares insights from managing 84,000 tests, scaling across 10 PostgreSQL databases, and maintaining Rails upgrades across a fast-moving organization using systematic approaches like dual-boot deployments and careful backporting strategies.
 
Tools & Libraries Mentioned

• AWS Aurora (PostgreSQL) – Production database platform, scaled to 10+ writers and 15+ readers.
• Capybara – End-to-end testing of UI flows in the monolith.
• Capybara Lockstep –JavaScript sync layer reducing flakiness in React-driven feature specs.
• Datadog – Application performance monitoring for production systems.
• Docker – Local PostgreSQL and other data stores.
• FactoryBot – Identified as a major performance bottleneck in large test suites.
• factory_fixtures – Shopify gem extending fixtures with inline factory-style overrides. 
• GitHub Copilot – Workflow automation and onboarding support.
• Heroku CI – Previously used for parallelized CI builds before moving to custom infrastructure.
• Jenkins – Original CI platform before scaling up to more powerful infrastructure.
• Minitest – Primary test framework, used throughout the monolith with some extensions.
• Packwerk – Used to modularize their monolith into engines with explicit boundaries and dependency declarations. 
• PostgreSQL – Core relational database behind their production and local environments.
• React – Primary frontend framework, integrated into the Rails monolith via a single-page app architecture. 
• Ruby on Rails – The framework behind Doctolib’s 3-million-line monolith and most of their core product infrastructure.
• safe-pg-migrations – Tool to reduce downtime risks during large-scale schema changes.
• Sentry – Error tracking and visibility tool integrated into their release workflow.
• Webpack Dev Server – Used locally to support React development alongside the Rails app.

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On Rails is a podcast focused on real-world technical decision-making, exploring how teams are scaling, architecting, and solving complex challenges with Rails. 

On Rails is brought to you by The Rails Foundation, and hosted by Robby Russell of Planet Argon, a consultancy that helps teams modernize their Ruby on Rails applications.

In this episode of On Rails, Robby is joined by Hilary Stohs-Krause, a Senior Software Engineer at Red Canary. They explore how engineering teams approach everyday performance work, from small Active Record optimizations to larger architectural decisions. Hilary shares insights from Red Canary's journey switching from React to Rails' native Hotwire stack, how her team tackled flaky test failures that were slowing down continuous deployments, and some strong opinions about custom linters.

🧰 Tools, Libraries, and Books Mentioned

• RuboCop – Enforces Ruby style and conventions, with support for custom cops.
• haml-lint – Linter for HAML templates to enforce consistent view code.
• ESLint – JavaScript linter used for maintaining consistent code quality, especially in React.
• HadoLint – Linter for Dockerfiles to catch common issues and enforce best practices.
• SitePrism – Page-object model DSL for Capybara to reduce flaky system tests.
• Sidekiq – Background job processor used in production Rails environments.
• Turbo – Part of the Hotwire stack for reactive updates without full-page reloads.
• Stimulus – Lightweight JavaScript framework for enhancing HTML with small interactions.
• Hotwire – A set of tools (Turbo + Stimulus) for building modern web apps without heavy JavaScript.
• Thinking in Bets – A book about better decision-making under uncertainty, by Annie Duke.

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On Rails is a podcast focused on real-world technical decision-making, exploring how teams are scaling, architecting, and solving complex challenges with Rails. 

On Rails is brought to you by The Rails Foundation, and hosted by Robby Russell of Planet Argon, a consultancy that helps teams modernize their Ruby on Rails applications.

In this episode of On Rails, Robby is joined by Ryan Stawarz and Austin Story from Doximity, where Ruby on Rails has powered the core of their platform for over 15 years. The trio digs into how a single Rails monolith has evolved to support 100+ engineers and a mobile-first experience for millions of healthcare professionals. From front-end framework migrations to API architecture, they explore the real-world decisions required to keep a large Rails app resilient and fast-moving.

Ryan and Austin walk us through the team’s adoption of GraphQL, what led them to introduce GraphQL Federation, and how they balance speed with reliability when scaling APIs across domains. They talk about the tradeoffs of maintaining both GraphQL and REST, and how Doximity avoids N+1 query pitfalls using BatchLoader. The conversation also touches on the evolution of their front-end—from Backbone to Vue.js—and why Rails’ flexibility still gives them an edge.

Throughout the episode, they share pragmatic insights into debugging at scale, managing one-off data migrations, and determining when a service should live inside or outside the monolith. They also reflect on their use of tools like Packwerk, AnyCable, and Departure, and how a culture of trust, documentation, and lightweight planning helps Doximity move fast without breaking things.

🧰 Tools & Libraries Mentioned

- Ruby on Rails – The web framework powering Doximity’s monolith and many of their services.  

- GraphQL-Ruby – Ruby gem for building GraphQL APIs in Rails.  

- BatchLoader– Helps reduce N+1 queries in GraphQL.  

- Vue.js – Their chosen frontend framework for building single-page applications.  

- Packwerk – Helps enforce modular boundaries in their Rails monolith.  

- Departure – Used for safe database migrations on large datasets.  

- Thor – Used to run one-off CLI scripts with easier testability.  

- rake-ui – Internal tool for triggering Rake tasks via a web UI.  

- AnyCable – Go-based replacement for ActionCable to support realtime features at scale.  

- Docker – Powers consistent local dev and containerized environments.  

- Firebase – Used for push notifications in mobile apps.  

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On Rails is a podcast focused on real-world technical decision-making, exploring how teams are scaling, architecting, and solving complex challenges with Rails. 

On Rails is brought to you by The Rails Foundation, and hosted by Robby Russell of Planet Argon, a consultancy that helps teams modernize their Ruby on Rails applications.

In this episode of On Rails, Nadia Odunayo, founder and solo developer of The StoryGraph, joins us to share what it really takes to build and maintain a Rails application used by over four million readers across web and mobile.

We discuss lessons from launching a PWA, shifting to Turbo Native for cross-platform support, and navigating challenges like in-app purchases and data syncing between systems. Nadia also talks about the bold decision to move from Heroku to YugabyteDB to support growing workloads, and why she decided against hiring a team to manage it.

We also explore what it means to remain a solo developer by choice, the value of the Rails community, and why Ruby on Rails continues to be the framework that powers her entire business. 

Platforms & Distribution

• The StoryGraph – Nadia’s solo-built reading and book tracking platform 
• Apple App Store – The StoryGraph
• Google Play Store – StoryGraph 
• Progressive Web Apps (MDN) – Alternative mobile delivery method initially explored

Tools, Libraries & Services

• Ruby on Rails – The primary framework powering The StoryGraph 
• Turbo / Hotwire Native – Used to support mobile apps with shared Rails backend 
• Devise (GitHub) – Authentication library for Rails 
• Sidekiq – Background job processor 
• Makara (GitHub) – Database proxy for master/replica load splitting 
• Heroku – Former hosting platform for The StoryGraph 
• YugabyteDB – Postgres-compatible distributed database chosen for scaling 
• CTEs (Common Table Expressions) – Used for optimizing queries across distributed data
• Linear – Project management tool currently used by Nadia

Books

• Ruby Under a Microscope by Pat Shaughnessy – A deep dive into Ruby internals 

Send us Fan Mail

On Rails is a podcast focused on real-world technical decision-making, exploring how teams are scaling, architecting, and solving complex challenges with Rails. 

On Rails is brought to you by The Rails Foundation, and hosted by Robby Russell of Planet Argon, a consultancy that helps teams modernize their Ruby on Rails applications.

Jean Boussier, Senior Staff Engineer at Shopify and member of the Rails Core team, joins Robby to dig into the performance realities behind modern Rails apps.

They explore what it means to be IO-bound or CPU-bound, how Ruby’s Global VM Lock affects concurrency, and why "fast" is too vague to be useful. Jean explains why instrumentation is often the missing piece and shares thoughtful approaches to using background jobs with intention.

They also talk about gem dependencies. The gems in your `Gemfile` are not magic. If your app depends on them, you should understand them. You can read the code. You can patch it. You can make it your own.

This episode is a reminder that Rails is not a black box. It is a system you can study, shape, and improve. The more you learn how it works, the more confidently you can build with it.

🔗 References & Resources Mentioned

- 📖 Crafting Interpreters – A book Jean recommends for understanding how interpreters and Ruby internals work  

- 🧵 GVL Tools (Shopify gem) – A tool for measuring thread contention in Ruby apps  

- 📊 AppSignal – Monitoring platform that integrates with GVL instrumentation  

- 🚢 ShipIt Engine – Shopify’s open-source deployment tool  

- 🔒 Ruby’s Global VM Lock – Overview of what the GVL is and how it works  

- 🦄 Unicorn – A classic preforking Ruby web server  

- 🐆 Puma – A multi-threaded Ruby/Rack web server  

- 🔀 Pitchfork – Shopify’s fork of Unicorn, optimized for their infrastructure  

- ⚙️ ActiveRecord Async Queries – Jean’s Rails Core contribution for backgrounding slow queries  

- 🔗 GraphQL – Used at Shopify to structure and query API data

Send us Fan Mail

On Rails is a podcast focused on real-world technical decision-making, exploring how teams are scaling, architecting, and solving complex challenges with Rails. 

On Rails is brought to you by The Rails Foundation, and hosted by Robby Russell of Planet Argon, a consultancy that helps teams modernize their Ruby on Rails applications.