Background: Hanami's Architectural Approach

Hanami promotes a modular architecture, splitting applications into slices that encapsulate related code, such as actions, views, and repositories. It encourages dependency inversion, minimal shared state, and explicit data flows. While this architecture reduces coupling, it also requires careful dependency management and precise configuration for reliable operation.

  • Slices are loaded lazily and independently.
  • Repositories abstract database access via ROM (Ruby Object Mapper).
  • Routing is centralized but can span multiple slices.
  • Configuration is environment-specific, impacting deployment pipelines.

Common Enterprise-Level Challenges

  • Slice autoload failures in containerized environments due to missing require paths.
  • ROM migration drift between staging and production databases.
  • Slow request handling under threaded Puma or Falcon servers due to blocking I/O in repositories.
  • Environment variable misalignment in CI/CD pipelines.

Diagnostics: Identifying Root Causes

1. Slice Loading Errors

When a slice fails to load, requests to its routes return 404 or 500 errors. Inspect load paths and ensure all slice files are required in config/environment.rb.

# Check slice loading in console
hanami console
Hanami.app.slices.keys

2. ORM Migration Drift

Schema mismatches often occur when ROM migrations aren't consistently applied across environments.

hanami db prepare
hanami db migrate

Verify schema versions match using database inspection tools and ensure migration scripts are idempotent.

3. Threading and Concurrency Bottlenecks

Blocking database calls in a multi-threaded environment reduce throughput.

# Example: Enable DB connection pool for Puma
max_threads_count = ENV.fetch("RAILS_MAX_THREADS") { 5 }
pool: <%= max_threads_count %>

Profile requests with tools like rack-mini-profiler to detect blocking calls.

4. Environment Misconfiguration

Differences in ENV variables between staging and production can cause missing credentials or incorrect service endpoints.

printenv | grep HANAMI

Automate environment validation in your deployment pipeline.

Common Pitfalls

  • Forgetting to preload slices in production: Lazy loading can fail in compiled deployment packages.
  • Not version-controlling migration status: Leads to drift and production downtime.
  • Using blocking I/O in threaded environments: Starves the thread pool under load.
  • Hardcoding environment values: Breaks flexibility and portability.

Step-by-Step Resolution Process

Step 1: Confirm Slice Integrity

Run hanami console and inspect loaded slices. Explicitly require missing slices in the application bootstrap file.

Step 2: Synchronize Database Schemas

Establish automated migration runs as part of your CI/CD process. Fail builds if migrations are pending.

Step 3: Optimize for Concurrency

Switch blocking calls to async patterns where possible and ensure the database pool matches your thread count.

Step 4: Standardize Environment Config

Use dotenv or a secrets manager to enforce consistency across environments.

Step 5: Add Observability

Integrate request tracing, database query metrics, and error tracking to quickly spot regressions.

Best Practices for Long-Term Stability

  • Preload all slices in production to avoid lazy-load race conditions.
  • Keep migrations small, frequent, and reversible.
  • Use async job queues for blocking I/O.
  • Maintain a unified environment configuration strategy.
  • Instrument applications with structured logging and metrics collection.

Conclusion

Hanami's modular architecture and clean design philosophy provide strong foundations for enterprise applications, but operational success at scale requires disciplined slice management, database synchronization, and concurrency tuning. By adopting proactive monitoring, environment standardization, and careful dependency handling, organizations can prevent the subtle but costly issues that often emerge in production Hanami deployments.

FAQs

1. Why do my Hanami slices fail to load after deployment?

Ensure all slice files are preloaded in production and that require paths are correct. Containerized builds often omit files if not explicitly required.

2. How can I avoid schema drift between environments?

Automate migrations in CI/CD and run them before application startup in each environment.

3. What causes slow throughput on threaded servers?

Blocking I/O operations in repositories can stall threads. Use async processing or ensure adequate DB connection pooling.

4. How do I prevent environment variable misalignment?

Centralize configuration in a single secrets manager or environment file and validate before deploys.

5. What tools are recommended for monitoring Hanami performance?

Rack-mini-profiler for request profiling, Skylight or New Relic for performance monitoring, and structured logging for error correlation.