OpenIDConnect

Client library for consuming and working with OpenID Connect Providers

OpenIDConnect is built and maintained by DockYard, contact us for expert Elixir and Phoenix consulting.

Installation

Available in Hex, the package can be installed as:

Add openid_connect to your list of dependencies in mix.exs:

def deps do
  [{:openid_connect, "~> 1.0.0"}]
end

Getting Started

Configuration

Most of the functions expect a config map which means application developer should take care for the storage of those options, eg:

google_config = %{
  discovery_document_uri: "https://accounts.google.com/.well-known/openid-configuration",
  client_id: "CLIENT_ID",
  client_secret: "CLIENT_SECRET",
  redirect_uri: "https://example.com/session",
  response_type: "code",
  scope: "openid email profile"
}

authorization_uri(google_config)

Most major OAuth2 providers have added support for OpenIDConnect. See a short list of most major adopters of OpenIDConnect.

Usage

In your app code you will need to do a few things:

1. Expose the authorization_uri for the provider(s)
2. Have your app handle the redirect from the provider
3. Fetch the JWT
4. Verify the JWT from the provider
5. Read the claim payload to set whatever session data your app requires

Exposing the authorization uri

You can build the correct authorization URI for a provider with:

OpenIDConnect.authorization_uri(google_config)

In this case we are requesting that OpenIDConnect build the authorization URI for the google provider. You should use this URI for your users to link out to for authenticating with the given provider

Handling the redirect from the provider

You will need an endpoint for the provider to redirect to after the user has authenticated. This is where the remainder of your steps will take place.

Fetch the JWT

The JSON Web Token (JWT) must be fetched, using the key/value pairs from the response_type params that were part of the redirect to your application:

{:ok, tokens} = OpenIDConnect.fetch_tokens(google_config, %{code: params["code"]})

Verify the JWT

The JWT is encrypted and it should always be verified with the JSON Web Keys (JWK) for the provider:

{:ok, claims} = OpenIDConnect.verify(google_config, tokens["id_token"])

The claims is a payload with the information from the scopes you requested of the provider.

Read the claims and set your app's user session

Now that you have the claims payload you can use the user data to identify and set the user's session state for your app. Setting your app's session state is outside the scope of this library.

Phoenix Example

# router.ex
get("/session", SessionController, :create)
get("/session/authorization-uri", SessionController, :authorization_uri)

# session_controller.ex
# you could also take the `provider` as a query param to pass into the function
def authorization_uri(conn, _params) do
  google_config = Application.fetch_env!(:my_app, :google_oidc_config)
  {:ok, uri} = OpenIDConnect.authorization_uri(google_config)
  
  json(conn, %{uri: uri})
end

# The `Authentication` module here is an imaginary interface for setting session state
def create(conn, params) do
  google_config = Application.fetch_env!(:my_app, :google_oidc_config)

  with {:ok, tokens} <- OpenIDConnect.fetch_tokens(google_config, params["code"]),
       {:ok, claims} <- OpenIDConnect.verify(google_config, tokens["id_token"]),
       {:ok, user} <- Authentication.call(google_config, Repo, claims) do

    conn
    |> put_status(200)
    |> render(UserView, "show.html", data: user)
  else
    _ -> send_resp(conn, 401, "")
  end
end

Authors

• Brian Cardarella

We are very thankful for the many contributors

Versioning

This library follows Semantic Versioning

Looking for help with your Elixir project?

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Legal

DockYard, Inc. © 2018

@dockyard

Licensed under the MIT license