On Rails Miguel Conde & Peter Compernolle: Inside Gusto’s Rails Biolith
Nov 3, 2025
Miguel Conde is an engineering leader at Gusto, specializing in breaking down the Rails monolith to create smaller services, while Peter Compernolle heads the HIPAA-compliant benefits domain. They discuss the innovative 'biolith' structure at Gusto, exploiting Rails for rapid development and how they enhance safety with explicit boundaries. Key topics include managing eventual consistency, using Packwerk for code isolation, and adopting Sorbet for type safety. They also delve into how to architect data handling and test effectively in a large-scale environment.
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Biolith Architecture Enables Safer Speed
- Gusto runs a biolith: two Rails monoliths split by domain and compliance needs.
- The benefits monolith isolates PHI and reduced coupling, enabling faster iteration for that product.
Use Packwerk Plus Types To Find Boundaries
- Use Packwerk to surface and enforce module boundaries before extraction.
- Combine Packwerk with Sorbet typings to make dependencies explicit and discover hotspots.
Introduce Sorbet Incrementally
- Adopt Sorbet gradually and annotate critical files first.
- Use increasing strictness to build trust in signatures before relying on them for refactors.
