Miguel Conde & Peter Compernolle: Inside Gusto’s Rails Biolith
In this episode of OnRails, 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 MentionedActiveAdmin: 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.Send us a textOn 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.
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1:32:34
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1:32:34
Alexander Stathis: Scaling a Modular Rails Monolith at AngelList
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 MentionedActive 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 LarsSend us a textOn 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.
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1:28:51
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1:28:51
Florent Beaurain: Optimizing Rails Tests at Doctolib Scale
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 MentionedAWS 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 Send us a textOn 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.
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1:18:09
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1:18:09
Hilary Stohs-Krause: Scaling Rails with Small Wins
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 MentionedRuboCop – 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.Send us a textOn 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.
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1:27:38
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1:27:38
Ryan Stawarz & Austin Story: Inside Doximity’s 15-Year Rails Monolith
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 consistSend us a textOn 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.
On Rails invites Rails developers to share real-world technical challenges and solutions, architectural decisions, and lessons learned while building with Rails. Through technical deep-dives and retrospectives with experienced engineers in the Rails community, we explore the strategies behind building and scaling Rails applications.Hosted by Robby Russell of Planet Argon.
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