falcon

Falcon is a multi-process, multi-fiber rack-compatible HTTP server built on top of async, async-container and async-http. Each request is executed within a lightweight fiber and can block on up-stream requests without stalling the entire server process. Falcon supports HTTP/1 and HTTP/2 natively.

Motivation

Initially, when I developed async, I saw an opportunity to implement async-http: providing both client and server components. After experimenting with these ideas, I decided to build an actual web server for comparing and validating performance primarily out of interest. Falcon grew out of those experiments and permitted the ability to test existing real-world code on top of async.

Once I had something working, I saw an opportunity to simplify my development, testing and production environments, replacing production (Nginx+Passenger) and development (Puma) with Falcon. Not only does this simplify deployment, it helps minimize environment-specific bugs.

My long term vision for Falcon is to make a web application platform which trivializes server deployment. Ideally, a web application can fully describe all its components: HTTP servers, databases, periodic jobs, background jobs, remote management, etc. Currently, it is not uncommon for all these facets to be handled independently in platform specific ways. This can make it difficult to set up new instances as well as make changes to underlying infrastructure. I hope Falcon can address some of these issues in a platform agnostic way.

As web development is something I'm passionate about, having a server like Falcon is empowering.

Priority Business Support

Falcon can be an important part of your business or project, both improving performance and saving money. As such, priority business support is available to make every project a success. The support agreement will give you:

• Direct support and assistance via Slack and email.
• Advance notification of bugs and security issues.
• Priority consideration of feature requests and bug reports.
• Better software by funding development and testing.

Please visit Socketry.io to register and subscribe.

Usage

Please see the project documentation for more details.

• Getting Started - This guide gives an overview of how to use Falcon for running Ruby web applications.

• Rails Integration - This guide explains how to host Rails applications with Falcon.

• Deployment - This guide explains how to deploy applications using the Falcon web server. It covers the recommended deployment methods, configuration options, and examples for different environments, including systemd and kubernetes.

• Performance Tuning - This guide explains the performance characteristics of Falcon.

• WebSockets - This guide explains how to use WebSockets with Falcon.

• Interim Responses - This guide explains how to use interim responses in Falcon to send early hints to the client.

• How It Works - This guide gives an overview of how Falcon handles an incoming web request.

Releases

Please see the project releases for all releases.

v0.52.4

• Relax dependency on async-container-supervisor to allow ~> 0.6.

v0.52.0

• Modernized codebase and dropped support for Ruby v3.1.
• Improved Rails integration documentation.
• Added extra logging of RUBY_DESCRIPTION.
• Minor documentation improvements.
• Agent context is now available, via the agent-context gem.

v0.51.0

• Introduce Falcon::Environment::Server#make_server which gives you full control over the server creation process.
• Introduce Async::Container::Supervisor.

v0.50.0

• Add Falcon::Environment::Server#endpoint_options to allow configuration of the endpoint options more easily.

v0.49.0

• Falcon Server Container Health Checks
• Falcon Server Process Title

v0.48.4

• Improve compatibility of rackup handler w.r.t. sinatra.

v0.47.8

• Fix Falcon Supervisor implementation: due to invalid code, it was unable to start.

Compatibility Fixes

During the v0.44.0 release cycle, the workflows for testing older rack releases were accidentally dropped. As such, v0.44.0 was not compatible with older versions of rack. This release restores compatibility with older versions of rack.

Specifically, protocol-rack now provides Protocol::Rack::Adapter.parse_file to load Rack applications. Rack 2's Rack::Builder.parse_file returns both the application and a set of options (multi-value return). Rack 3 changed this to only return the application, as the prior multi-value return was confusing at best. This change allows protocol-rack to work with both versions of rack, and falcon adopts that interface.

Falcon Serve Options

In addition, falcon serve provides two new options:

• --[no]-restart which controls what happens when async-container instances crash. By default, falcon serve will restart the container when it crashes. This can be disabled with --no-restart.

• --graceful-stop [timeout] which allows you to specify a timeout for graceful shutdown. This is useful when you want to stop the server, but allow existing connections to finish processing before the server stops. This feature is highly experimental and doesn't work correctly in all cases yet, but we are aiming to improve it.

Falcon Host

async-service is a new gem that exposes a generic service interface on top of async-container. Previously, falcon host used async-container directly and build-environment for configuration. In order to allow for more generic service definitions and configuration, async-service now provides a similar interface to build-environment and exposes this in a way that can be used for services other tha falcon. This makes it simpler to integrate multiple services into a single application.

The current configuration format uses definitions like this:

rack "hello.localhost", :self_signed_tls

This changes to:

service "hello.localhost" do
	include Falcon::Environment::Rack
	include Falcon::Environment::SelfSignedTLS
end

Contributing

We welcome contributions to this project.

• Fork it.
• Create your feature branch (git checkout -b my-new-feature).
• Commit your changes (git commit -am 'Add some feature').
• Push to the branch (git push origin my-new-feature).
• Create new Pull Request.

Developer Certificate of Origin

In order to protect users of this project, we require all contributors to comply with the Developer Certificate of Origin. This ensures that all contributions are properly licensed and attributed.

Community Guidelines

This project is best served by a collaborative and respectful environment. Treat each other professionally, respect differing viewpoints, and engage constructively. Harassment, discrimination, or harmful behavior is not tolerated. Communicate clearly, listen actively, and support one another. If any issues arise, please inform the project maintainers.