How do I temporarily disable Spring?

Set the DISABLE_SPRING environment variable; this bypasses Spring for the current session, allowing commands to run without the preloader, as mentioned in the README.

Spring vs running Rails commands normally?

Spring preloads the Rails environment, making subsequent runs faster by avoiding boot time, whereas normal runs reboot the app each time, which is slower but more isolated and predictable.

How to fix Spring not detecting file changes?

Ensure config/enable_reloading is true in your environment files, and consider installing spring-watcher-listen for event-based watching instead of default polling, which reduces CPU usage.

Can I use Spring with Docker?

Yes, but it requires specific configuration; the README points to an example repository for Docker setup, involving adjustments to handle process forking in containers.

Why are my constants breaking with Spring?

Spring's reloading changes object identities of constants; avoid saving references to them in initializers, as detailed in the class reloading section to prevent mismatches.

How to remove Spring from my Rails project?

Run 'bin/spring binstub --remove --all' to unspring executables, then remove the gem from your Gemfile, following the removal steps in the README for a clean exit.

spring

MITRubyv4.4.2

A Rails application preloader that speeds up development by keeping the app running in the background.

GitHub

2.8k stars341 forks0 contributors

What is spring?

Spring is a preloader for Ruby on Rails applications that accelerates development workflows by keeping the application running in a background process. It eliminates the need to reboot the entire Rails environment for common tasks like running tests, migrations, or Rake tasks, significantly reducing wait times during iterative development.

Target Audience

Ruby on Rails developers working in development or test environments who frequently run commands like tests, Rake tasks, or migrations and want to reduce boot times. It is specifically for those using MRI Ruby 3.1+ and Rails 7.1+ on platforms that support process forking (not Windows or JRuby).

Value Proposition

Developers choose Spring for its seamless, zero-configuration experience that automatically manages background processes and reloads code, offering a significant speed boost over manually restarting the Rails environment for each command. Its unique selling point is leveraging Ruby's process forking to maintain application state, with automatic restarts when configuration or dependencies change.

Overview

Rails application preloader

Use Cases

Best For

Speeding up test runs in Rails applications by avoiding repeated environment booting.

Related Projects

Community-curated · Updated weekly · 100% open source

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Accelerating iterative development cycles where developers frequently run Rake tasks or migrations.

Reducing wait times for Rails console, generator, and runner commands during active coding sessions.

Maintaining separate preloaded instances for different Rails environments like test and development.

Integrating with additional tools like RSpec, RuboCop, or Cucumber via community gems for faster command execution.

Development workflows on Unix-like platforms that support process forking, where automatic code reloading is beneficial.

Not Ideal For

Development on Windows or JRuby platforms, as Spring relies on process forking which is unsupported there.
Production deployments where Spring is explicitly discouraged and could introduce unnecessary complexity.
Projects with heavy use of global constants saved in initializers, due to Spring's code reloading causing object identity issues.
Teams using containerized environments without prior Docker configuration experience, as Spring requires additional setup for proper operation.

Pros & Cons

Pros

Automatic Background Process

Spring runs silently without manual start/stop, initiating on first command use and terminating when the terminal closes, streamlining development workflows.

Efficient Code Reloading

It automatically reloads changed application code between runs, leveraging Rails' reloading mechanism to keep code current without full environment reboots.

Configuration-Aware Restarts

Spring detects changes to config files, initializers, or Gemfile dependencies and restarts the application automatically, ensuring consistency.

Multi-Environment Support

Manages separate preloaded instances for different Rails environments like test and development, reducing boot times for context switches.

Cons

Platform Limitations

Spring only works on platforms that support process forking, excluding Windows and JRuby, which limits its adoption for cross-platform teams.

Setup and Configuration Complexity

Requires binstub generation and additional configuration for non-standard app structures or containerized setups, adding overhead compared to vanilla Rails.

Reloading Pitfalls

Code reloading can cause subtle bugs if application constants are saved in initializers, as warned in the README, leading to hard-to-debug issues.

Frequently Asked Questions

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