Why?

benefits of upgrading

Security & Bug Fixes

Features

• Database Safety
• ActiveStorage
• ActiveRecord::Relation or and left_outer_joins
• ActiveRecord::Enum
• ActiveJob
• ActionCable
• ActionMailer before filters w/ params
• HTTP/2 Early Hints
• Content Security Policy

Performance

• 50% faster boot time with Bootsnap
• 11% faster request speed
• 29% decrease in object allocation (memory)

Experience

&

Community

Why not?

costs of upgrading

Costs

• Developer Time
• Bugs and Instability
• Disruption and extra effort
• Dependency issues with gems
• $$$ running multiple builds

Changes

what you need to know

Controller Request Tests

Versioned Migrations

Request Helpers (Test)

Rails TEST Command

CircleCi Rails NEXT

Timeline

• Rails 5 testing ASAP
• Rails 5.0 master end of Sprint 49
• Rails 5.1 and 5.2 in next sprint
• Rails 6.0.0-beta2 tests Sprint 51

Lessons

what we learned

Update Strategy

• Incremental Compatibility
• Easy switching between versions
• Static Code Analysis (Rubocop)
• Dual Test Builds

🔥 Dependency Hell 🔥

• Locked dependencies
  • Relastik
  • Internal gems/engines
• Poorly maintained gems 
  • Flip
  • HerokuRailsDeflate
• Entangled Dependencies
  • delayed_job_web, sinatra, rack

✅ Explicit Code ✅

• Meta Programming 😢
• Monkey-patching 😢
• Unconventional Code 😢