Corsica

Corsica is a plug and a DSL for handling CORS requests. Documentation can be found online.

(I had to include a nice pic because, let's be honest, CORS requests aren't the most fun thing in the world, are they?)

Features

• Is compliant with the W3C CORS specification
• Provides both low-level CORS utilities as well as high-level facilities (like a built-in plug and a CORS-focused router)
• Handles preflight requests like a breeze
• Never sends any CORS headers if the CORS request is not valid (smaller requests, yay!)

Installation

Just add the :corsica dependency to your project's mix.exs:

defp dependencies do
  [{:plug, "~> 1.0"},
   {:corsica, "~> 0.4"}]
end

and then run $ mix deps.get. Corsica is a plug and thus depends on Plug too, but you have to explicitly list Plug as a dependency of your project (since the dependency is optional: true in Corsica).

Overview

You can use Corsica both as a plug as well as a router generator. To use it as a plug, just plug it into your plug pipeline:

defmodule MyApp.Endpoint do
  plug Logger
  plug Corsica, origins: "http://foo.com"
  plug MyApp.Router
end

To gain finer control over which resources are CORS-enabled and with what options, you can use the Corsica.Router module:

defmodule MyApp.CORS do
  use Corsica.Router,
    origins: ["http://localhost", ~r{^https?://(.*\.?)foo\.com$}],
    allow_credentials: true,
    max_age: 600,

  resource "/public/*", origins: "*"
  resource "/*"
end

defmodule MyApp.Endpoint do
  plug Logger
  plug MyApp.CORS
  plug MyApp.Router
end

This is only a brief overview of what Corsica can do. To find out more, head to the online documentation.

Contributing

If you find a bug, something unclear (including in the documentation!) or a behaviour that is not compliant with the latest revision of the official CORS specification, please open an issue on GitHub.

If you want to contribute to code or documentation, fork the repository and then open a Pull Request (how-to). Before opening a Pull Request, make sure all the tests passes by running $ mix test in your shell. If you're contributing to documentation, you can preview the generated documentation locally by running:

$ MIX_ENV=docs mix do deps.get, docs

Documentation will be generated in the doc/ directory.

License

MIT © 2015 Andrea Leopardi, see the license file.