Getting Started
This guide gives an overview of how to use Falcon for running Ruby web applications.
Installation
Add the gem to your project:
$ bundle add falcon
Or, if you prefer, install it globally:
$ gem install falcon
Core Concepts
Falcon is a high-performance web server for Ruby. It is designed to be fast, lightweight, and easy to use.
- Asynchronous: Falcon is built on top of the fiber scheduler and the async gem which allow it to handle thousands of connections concurrently.
- Rack Compatible: Falcon is a Rack server. It can run any Rack application, including Rails, Sinatra, and Roda with no modifications.
- Secure: Falcon supports TLS out of the box. It can generate self-signed certificates for localhost.
- HTTP/2: Falcon is build on top of the async-http gem which supports HTTP/2. It can serve multiple requests over a single connection.
- WebSockets: Falcon supports WebSockets using the async-websocket gem which takes advantage of Rack 3 streaming responses. You can build complex real-time applications with ease.
Rack
Falcon is a Rack server. This means it can run any Rack application, including Rails, Sinatra, and Roda. It is compatible with the Rack 2 and Rack 3 specifications. Typically these applications have a config.ru
file that defines the application. Falcon can run these applications directly:
# config.ru
run do |env|
[200, {'Content-Type' => 'text/plain'}, ['Hello, World!']]
end
Then run the application with:
$ falcon serve
Running a Local Server
For local application development, you can use the falcon serve
command. This will start a local server on https://localhost:9292
. Falcon generates self-signed certificates for localhost
. This allows you to test your application with HTTPS locally.
To run on a different port:
$ falcon serve --port 3000
Unencrypted HTTP
If you want to run Falcon without TLS, you can use the --bind
option to bind to an unencrypted HTTP endpoint:
$ falcon serve --bind http://localhost:3000
Using with Rackup
You can invoke Falcon via rackup
:
$ rackup --server falcon
This will run a single-threaded instance of Falcon using http/1
. While it works fine, it's not recommended to use rackup
with falcon
, because performance will be limited.