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.

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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 –
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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.