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Rails API Profiler

Rails API Profiler is a lightweight, middleware-based performance profiling tool for Rails API applications. It provides request-level insights such as response time, database query count, and database execution time — with zero changes to your controllers or business logic.

Designed to be simple, fast, and production-safe, it supports Rails 5 and above.

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✨ Features

• 🚀 Measures API request duration
• 🗄️ Tracks ActiveRecord query count
• ⏱️ Tracks total database execution time
• ⚙️ Middleware-based (no controller code required)
• 🔕 Can be enabled/disabled via configuration
• 🧪 Safe for development, staging, and debugging
• 🧩 Works with Rails 5+

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📦 Installation

Add the gem to your Gemfile:

gem "rails_api_profiler", group: [:development, :staging]

Then install:

bundle install

That’s it — no further setup required.

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⚙️ Configuration

You can optionally configure the profiler in an initializer:

# config/initializers/rails_api_profiler.rb

RailsApiProfiler.configure do |config|
  config.enabled = true
  config.slow_request_threshold = 500 # milliseconds
end

Available Options

Option	Description	Default
enabled	Enable or disable profiling	true
slow_request_threshold	Threshold for slow request warnings (ms)	500
logger	Custom logger instance	Rails.logger

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📊 Example Log Output

[RailsApiProfiler] {:method=>"GET",
:path=>"/api/v1/users",
:status=>200,
:duration_ms=>183.21,
:db_queries=>7,
:db_time_ms=>41.8}

For slow requests:

[RailsApiProfiler] SLOW REQUEST {:method=>"POST",
:path=>"/api/v1/orders",
:status=>201,
:duration_ms=>812.44,
:db_queries=>18,
:db_time_ms=>220.3}

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🧠 How It Works

• Uses a Rack middleware to measure request duration
• Hooks into ActiveSupport::Notifications to track SQL queries
• Stores per-request stats using thread-local storage
• Automatically attaches via a Rails Railtie

No monkey-patching. No controller hooks. No overhead outside requests.

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🧪 Supported Versions

• Rails: 5.0+
• Ruby: 2.4+

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🚧 When Should I Use This?

This gem is ideal when you want to:

• Identify slow API endpoints
• Detect excessive database queries
• Debug performance regressions
• Profile APIs in development or staging
• Keep instrumentation lightweight

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🛑 When NOT to Use This

• As a full APM replacement (Datadog, New Relic, etc.)
• For deep flamegraph analysis
• For long-running background jobs

This gem focuses on request-level clarity, not heavy analytics.

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🛣️ Roadmap

Planned improvements:

• JSON / structured log formatter
• N+1 query detection
• Prometheus exporter
• Memory usage tracking
• Optional endpoint filtering

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🤝 Contributing

Contributions are welcome!

1. Fork the repository
2. Create a feature branch
3. Add tests
4. Submit a pull request

Please ensure all specs pass before submitting.

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📄 License

This project is licensed under the MIT License.

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👤 Author

Sparsh Garg GitHub: https://github.com/sparsh9

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