Ring-OAuth2

Ring middleware that acts as a OAuth 2.0 client. This is used for authenticating and integrating with third party website, like Twitter, Facebook and GitHub.

Installation

To install, add the following to your project :dependencies:

[ring-oauth2 "0.1.4"]

Usage

The middleware function to use is ring.middleware.oauth2/wrap-oauth2. This takes a Ring handler, and a map of profiles as arguments. Each profile has a key to identify it, and a map of options that define how to authorize against a third-party service.

Here's an example that provides authentication with GitHub:

(require '[ring.middleware.oauth2 :refer [wrap-oauth2])

(def handler
  (wrap-oauth2
   routes
   {:github
    {:authorize-uri    "https://github.com/login/oauth/authorize"
     :access-token-uri "https://github.com/login/oauth/access_token"
     :client-id        "abcabcabc"
     :client-secret    "xyzxyzxyzxyzxyz"
     :scopes           ["user:email"]
     :launch-uri       "/oauth2/github"
     :redirect-uri     "/oauth2/github/callback"
     :landing-uri      "/"}}))

The profile has a lot of options, and all have a necessary function. Let's go through them one by one.

The first two keys are the authorize and access token URIs:

• :authorize-uri
• :access-token-uri

These are URLs provided by the third-party website. If you look at the OAuth documentation for the site you're authenticating against, it should tell you which URLs to use.

Next is the client ID and secret:

• :client-id
• :client-secret

When you register your application with the third-party website, these two values should be provided to you. Note that these should not be kept in source control, especially the client secret!

Optionally you can define the scope or scopes of the access you want:

• :scopes

These are used to ask the third-party website to provide access to certain information. In the previous example, we set the scopes to ["user:email"]; in other words, we want to be able to access the user's email address. Scopes are a vector of either strings or keywords, and are specific to the website you're authenticating against.

The next URIs are internal to your application:

• :launch-uri
• :redirect-uri
• :landing-uri

The launch URI kicks off the authorization process. Your log-in link should point to this address, and it should be unique per profile.

The redirect URI provides the internal callback. It can be any relative URI as long as it is unique. It can also be an absolute URI like https://loadbalanced-url.com/oauth2/github/callback

The landing URI is where the middleware redirects the user when the authentication process is complete. This could just be back to the index page, or it could be to the user's account page.

• :basic-auth?

This is an optional parameter, which defaults to false. If set to true, it includes the client-id and secret as a header Authorization: Basic base64(id:secret) as recommended by the specification.

Please note, you should enable cookies to be sent with cross-site requests, in order to make the callback request handling work correctly, eg:

(wrap-defaults (-> site-defaults (assoc-in [:session :cookie-attrs :same-site] :lax)))

Workflow diagram

The following image is a workflow diagram that describes the OAuth2 authorization process for Ring-OAuth2. It should give you an overview of how all the different URIs interact.

License

Copyright © 2017 James Reeves

Released under the MIT License.