CI Gates, Test Result Caches, and the Code Graph That Might Tell Us What to Test
What I learned from splitting Rails CI by risk, caching exact test results, and exploring whether AI and code graphs can make test selection safer.
Tag: rails
When a Green Deployment Still Serves a 500
A REX production incident exposed the gap between a successful Kubernetes rollout and a working application, and what we changed to close it.
When a Rails or LMS Platform Becomes Hard to Change
A practical way for small education and SaaS teams to diagnose Rails or LMS platform friction and decide whether a rewrite is actually justified.
When Ubuntu Builds Fail on libvips but macOS Does Not
Why a Rails test suite can fail on Ubuntu because of an older native libvips, and how to upgrade it safely without confusing it with the ruby-vips gem.
Local Gemma with Hermes: Cheap Delegation for Rails Maintenance
A practical guide to using Hermes Agent with a local Gemma model for routine coding work, while reserving cloud models for tasks that genuinely need them.
The CI failures that moved every time you reran them
How a moving set of Rails CI flakes exposed shared download state, Selenium stale-node retries, and specs asserting before the browser settled.
Deterministic Rails CI failures: read the evidence first
A Rails CI debugging story: following the evidence to shared test state, instead of weakening assertions to make failures disappear.
Rails Performance from the Metal Up: A Field Guide
A practical Rails performance field guide for diagnosing CPU, IO, GVL, GC, memory, Puma, and container-runtime bottlenecks before choosing a fix.
The callback that quietly doubled our database
A Rails after_save callback silently duplicated database rows: how the symptom appeared, why the obvious suspect was innocent, and the real root cause.
Rails UJS to Turbo: the event timing bug CI didn't catch
Migrating Rails UJS to Turbo can silently break submit buttons and resets in production, because Turbo's event timing and Promise handling differ from UJS.
Redis High Availability: Shared Sessions and Fault Tolerance
How to split Redis into isolated session, cache, and Sidekiq instances so a cache blip never logs users out or stops background jobs.
Git Worktree for Parallel AI Development
How to use git worktree to run parallel AI coding sessions safely, with practical patterns for isolating gems, databases, ports, and runtime state.
Faster Rails Docker Feedback Loop: Runtime Deps and HMR
How I reduced Docker development friction across three Rails apps by removing rebuild-heavy steps, adding runtime dependency sync, and enabling webpack HMR.
Polymorphic Indexes in MySQL: Type-First or ID-First?
A practical comparison of [type, id] versus [id, type] composite index order for polymorphic associations in Rails and MySQL, and how to choose.
Migrating a Rails App from Yarn + Webpacker to pnpm + Vite
A migration path from Webpacker and Yarn to pnpm and Vite in a Rails app, including the dependency, Docker, and asset-hash pitfalls we hit along the way.
Rails Style Guide: Transactions, Touch, and Async Derived Data
This document defines official patterns and anti-patterns for handling transactions, derived data, touch, and async updates in Rails services at my company.
Transactions, touch, and async rollups for derived data in Rails
Keeping counters and summaries accurate in Rails without slowing down writes means separating core data in a transaction from derived data updated after commit.
PostgreSQL on Ubuntu: install, user setup, and auth debugging
Install PostgreSQL from the PGDG repo on Ubuntu, set up a matching development role, and debug the password authentication failures Rails hits most.
load_async in Rails 8: loading associations concurrently
Rails 8's load_async runs association queries concurrently instead of one after another, and getting it right means sizing your connection pool correctly.
Rails 8.1.1 + connection_pool 3.x: RedisCacheStore boot crash
A keyword-argument mismatch between Ruby 3.4 and connection_pool 3.x breaks RedisCacheStore at Rails 8.1.1 boot, fixed with a patch loaded before initializers run.
From 499 to 200: Fixing Nginx Timeouts in a Rails API
How Puma worker timeouts and Nginx 499 errors expose slow Rails requests, and how to fix them with aligned timeouts, background jobs, and caching.
The Ghost in the Test Suite: Fixing Rails Database Cleanup
A flaky RSpec suite traced to a Rake task that commits data outside the per-test transaction, and how DatabaseCleaner's truncation strategy fixes it.
Why Using Business Logic for Test Setup Is a Rails Antipattern
Using application services to build test data couples your specs to that business logic, making test suites slow and fragile; Factory Bot traits fix it.
Active Storage Variants: Multiple Sizes and Testing Pitfalls
Active Storage's variant API gets rough past the basic thumbnail case: multiple sizes, per-attachment metadata, and tests that break on file-not-found errors.
User Impersonation in Rails with the Pretender Gem
User impersonation lets an admin temporarily act as another user for debugging and support, and the pretender gem handles the current_user switch and session state.
When to Mock and When to Hit the Real Thing in Rails Tests
A practical breakdown of when to mock external dependencies in Rails tests versus using the real thing, built around the test pyramid, VCR, WebMock, and Pact.
How button_to Changed in Rails 7 (and Broke Our CSS)
Rails 7's button_to wraps a form around the button instead of rendering a plain input, which silently breaks existing CSS selectors and JavaScript click handlers.
Managing Temporary Data in Multi-Step Rails Forms
Multi-step Rails forms need somewhere to hold data between steps, and this compares session storage, direct Redis caching, and temporary DB rows for that job.
Custom HTTP Headers in Rails: Picking the Right Format
Rails normalizes headers to HTTP_-prefixed names, which decides whether Accept, a legacy X- prefix, or a plain name is right for a custom API header.
How Rails Sessions Work with Warden and Cookies
Rails keeps users logged in by encrypting the whole session into a browser cookie, then lets Warden authenticate each request, which changes how you should test it.
Idempotent Rails Requests with a Redis Semaphore Lock
How to stop duplicate Rails requests from creating the same record twice, using a Redis-backed semaphore lock instead of chasing a race condition.
Timezone Bugs in Ruby: BST vs UTC in CI and Cron
How British Summer Time breaks Ruby tests, cron schedules, and cloud functions that assume UTC, and how to write timezone-aware specs instead.
Debugging Transaction Deadlocks in Rails Tests: A Case Study
A Rails test suite hung intermittently until transactional tests, ActiveJob, and ActiveStorage turned out to be racing over the same locked rows.
Avoiding Duplicate Record Errors in Rails Under Concurrency
Two concurrent requests can both pass an exists? check and race to insert the same row; here is why, and how to write idempotent Rails controllers.
Handling Out-of-Order Updates in Async Rails Workflows
When async updates to the same record can finish in any order, the oldest write can silently overwrite the newest one; here is how to stop that.
Ordering by an Associated Column Without Breaking includes
Why ordering ActiveRecord results by an associated table's column breaks with includes, and how references, Arel, and left_joins fix it for good.
N+1 Queries in Rails: What Silently Breaks `includes`
How ActiveRecord's includes prevents N+1 queries in Rails, and the common mistakes with order, filtering, and pluck that silently break it.
Building a Test Suite: Pyramid, Layers, and What to Skip
A framework for deciding how much to test: the testing pyramid, layered test responsibility by architecture tier, and what makes test data good.
Fixing Racing Background Job Updates: Rails to Laravel
How optimistic concurrency, unique job locks, and throttling stop out-of-order background job updates in both Rails/Sidekiq and Laravel queues.
Ruby object IDs, anonymous modules, and Rails cache errors
A Rails.cache TypeError on an anonymous module led into Ruby's Marshal restrictions and the relationship between object_id and C-level memory addresses.
Migrating from Kaminari to will_paginate in Rails
A step-by-step guide to migrating a Rails app's pagination from Kaminari to will_paginate, covering models, controllers, views, and API responses.
Why Kaminari's Anonymous Modules Break Rails Caching
Why Rails caching raises TypeError: can't dump anonymous module with Kaminari-paginated collections, and how to trace and fix the module causing it.
Rails in Kubernetes: Migrations, Jobs, and Puma
Running a Ruby on Rails app in Kubernetes means containerizing it correctly and handling migrations, background jobs, and Puma as separate concerns.
Upgrading to Rails 7.2: Four Breaking Changes We Hit
Four breaking changes we hit upgrading to Rails 7.2: show_exceptions, array-containment SQL, connection pool locking, and assert_enqueued_email_with.
Speeding Up Nested JSON Serialization in Rails
Caching, the Oj gem, eager loading, background jobs, and load_async each cut serialization time for deeply nested Rails associations like classrooms and scores.
delete_all vs destroy_all in Rails: Callbacks and Associations
delete_all skips callbacks and dependent associations while destroy_all runs them, and picking the wrong one silently breaks counter caches and cascades.
Inspecting Sidekiq Jobs from the Rails Console
Console-ready Ruby snippets to inspect Sidekiq queues, scheduled jobs, retry and dead sets, and currently running workers when the dashboard is not enough.
Rails N+1 Queries: joins vs preload vs eager_load vs includes
What joins, preload, eager_load, and includes actually do in ActiveRecord, shown with real SQL logs, plus the chained calls that quietly bring the N+1 back.
Production Debugging Techniques for Rails Apps
Practical production debugging techniques for Rails: log analysis, replicating production data, rbtrace live injection, feature-flagged debug modes, and replica apps.
Redis Memory Spikes: Tracking Down a Runaway Sidekiq Queue
How I traced a Redis memory jump from 130MB to 800MB back to an unthrottled Sidekiq integration, and the maxmemory, eviction, and unique-job fixes that followed.
A .irbrc Full of Ruby Debugging and Introspection Helpers
A collection of .irbrc helpers for tracing method calls, logging SQL queries, profiling code, and inspecting Ruby objects during Rails console debugging.
Rails Session Stores: Cookie, ActiveRecord, and Redis
A comparison of Rails session stores: cookie sessions, ActiveRecord, and Redis, including how to share sessions across subdomains and multiple apps.
Rails Secrets: Credentials, 1Password, and Cloud Vaults
A rundown of Rails credentials, environment variables, 1Password CLI, and cloud secret managers like AWS Secrets Manager and Vault, and when to use each.
How to Set a Breakpoint on Devise's current_user Method
Why byebug can't break on Devise's metaprogrammed current_user method, and several ways to debug or patch a method that isn't in your source.
Fragment Caching a Large List That Changes Constantly
How splitting static and dynamic fields, granular fragment caching, and incremental loading keep a large, frequently updated list fast without stale data.
Redis in Ruby on Rails: Cache Server and Job Queue
Redis serves two very different roles in a Rails app, a disposable read cache and a durable job queue, and conflating the two causes real outages.
Soft Delete in Rails: Discard vs ActsAsParanoid
A comparison of Discard and ActsAsParanoid, the two common Rails soft-delete gems, and the query and unscope pitfalls each one introduces.
How Rails Loads Your App: Rake, Console, Server, and Tests
What Rails actually loads when you run a rake task, the console, the server, or tests, and how to load rake tasks in each environment when you need them.
Rails unscope: removing default scope conditions
How ActiveRecord's unscope method selectively removes where and order conditions from default scopes, with examples and alternatives like merge and unscoped.
Database Auditing: pg_audit vs audited vs paper_trail
A comparison of database auditing options, pg_audit, audited, paper_trail, Hibernate Envers, and SQL Server temporal tables, and when each one fits.