The no-brainer library to use for adding OAuth 2.0 provider capabilities to your Elixir app. You can use phoenix_oauth2_provider for easy integration with your Phoenix app.
Add ExOauth2Provider to your list of dependencies in mix.exs
:
def deps do
[
# ...
{:ex_oauth2_provider, "~> 0.5.7"}
# ...
]
end
Run mix deps.get
to install it.
Generate the migrations and schema modules:
mix ex_oauth2_provider.install
Add the following to config/config.exs
:
config :my_app, ExOauth2Provider,
repo: MyApp.Repo,
resource_owner: MyApp.Users.User
If you don't have any user setup, you shuld consider setting up Pow
first.
You have to ensure that a resource_owner
has been authenticated on the following endpoints, and pass the struct as the first argument in the following methods.
# GET /oauth/authorize?response_type=code&client_id=CLIENT_ID&redirect_uri=CALLBACK_URL&scope=read
case ExOauth2Provider.Authorization.preauthorize(resource_owner, params, otp_app: :my_app) do
{:ok, client, scopes} -> # render authorization page
{:redirect, redirect_uri} -> # redirect to external redirect_uri
{:native_redirect, %{code: code}} -> # redirect to local :show endpoint
{:error, error, http_status} -> # render error page
end
# POST /oauth/authorize?response_type=code&client_id=CLIENT_ID&redirect_uri=CALLBACK_URL&scope=read
ExOauth2Provider.Authorization.authorize(resource_owner, params, otp_app: :my_app) do
{:redirect, redirect_uri} -> # redirect to external redirect_uri
{:native_redirect, %{code: code}} -> # redirect to local :show endpoint
{:error, error, http_status} -> # render error page
end
# DELETE /oauth/authorize?response_type=code&client_id=CLIENT_ID&redirect_uri=CALLBACK_URL&scope=read
ExOauth2Provider.Authorization.deny(resource_owner, params, otp_app: :my_app) do
{:redirect, redirect_uri} -> # redirect to external redirect_uri
{:error, error, http_status} -> # render error page
end
# POST /oauth/token?client_id=CLIENT_ID&client_secret=CLIENT_SECRET&grant_type=authorization_code&code=AUTHORIZATION_CODE&redirect_uri=CALLBACK_URL
case ExOauth2Provider.Token.grant(params, otp_app: :my_app) do
{:ok, access_token} -> # JSON response
{:error, error, http_status} -> # JSON response
end
# GET /oauth/revoke?client_id=CLIENT_ID&client_secret=CLIENT_SECRET&token=ACCESS_TOKEN
case ExOauth2Provider.Token.revoke(params, otp_app: :my_app) do
{:ok, %{}} -> # JSON response
{:error, error, http_status} -> # JSON response
end
Revocation will return {:ok, %{}}
status even if the token is invalid.
ExOauth2Provider doesn't support implicit grant flow. Instead you should set up an application with no client secret, and use the Authorize code grant flow. client_secret
isn't required unless it has been set for the application.
# POST /oauth/token?client_id=CLIENT_ID&client_secret=CLIENT_SECRET&grant_type=client_credentials
case ExOauth2Provider.Token.grant(params, otp_app: :my_app) do
{:ok, access_token} -> # JSON response
{:error, error, http_status} -> # JSON response
end
Refresh tokens can be enabled in the configuration:
config :my_app, ExOauth2Provider,
repo: MyApp.Repo,
resource_owner: MyApp.Users.User,
use_refresh_token: true
The refresh_token
grant flow will then be enabled.
# POST /oauth/token?client_id=CLIENT_ID&client_secret=CLIENT_SECRET&grant_type=refresh_token&refresh_token=REFRESH_TOKEN
case ExOauth2Provider.Token.grant(params, otp_app: :my_app) do
{:ok, access_token} -> # JSON response
{:error, error, http_status} -> # JSON response
end
You'll need to provide an authorization method that accepts username and password as arguments, and returns {:ok, resource_owner}
or {:error, reason}
. Here'a an example:
# Configuration in config/config.exs
config :my_app, ExOauth2Provider,
password_auth: {Auth, :authenticate}
# Module example
defmodule Auth do
def authenticate(username, password, otp_app: :my_app) do
User
|> Repo.get_by(email: username)
|> verify_password(password)
end
defp verify_password(nil, password) do
check_pw("", password) # Prevent timing attack
{:error, :no_user_found}
end
defp verify_password(%{password_hash: password_hash} = user, password) do
case check_pw(password_hash, password) do
true -> {:ok, user}
false -> {:error, :invalid_password}
end
end
end
The password
grant flow will then be enabled.
# POST /oauth/token?client_id=CLIENT_ID&grant_type=password&username=USERNAME&password=PASSWORD
case ExOauth2Provider.Token.grant(params, otp_app: :my_app) do
{:ok, access_token} -> # JSON response
{:error, error, http_status} -> # JSON response
end
Server wide scopes can be defined in the configuration:
config :my_app, ExOauth2Provider,
repo: MyApp.Repo,
resource_owner: MyApp.Users.User,
default_scopes: ~w(public),
optional_scopes: ~w(read update)
Looks for a token in the Authorization Header. If one is not found, this does nothing. This will always be necessary to run to load access token and resource owner.
Looks for a verified token loaded by VerifyHeader
. If one is not found it will call the :unauthenticated
method in the :handler
module.
You can use a custom :handler
as part of a pipeline, or inside a Phoenix controller like so:
defmodule MyAppWeb.MyController do
use MyAppWeb, :controller
plug ExOauth2Provider.Plug.EnsureAuthenticated,
handler: MyAppWeb.MyAuthErrorHandler
end
The :handler
module always defaults to ExOauth2Provider.Plug.ErrorHandler.
Looks for a previously verified token. If one is found, confirms that all listed scopes are present in the token. If not, the :unauthorized
function is called on your :handler
.
defmodule MyAppWeb.MyController do
use MyAppWeb, :controller
plug ExOauth2Provider.Plug.EnsureScopes,
handler: MyAppWeb.MyAuthErrorHandler, scopes: ~w(read write)
end
When scopes' sets are specified through a :one_of
map, the token is searched for at least one matching scopes set to allow the request. The first set that matches will allow the request. If no set matches, the :unauthorized
function is called.
defmodule MyAppWeb.MyController do
use MyAppWeb, :controller
plug ExOauth2Provider.Plug.EnsureScopes,
handler: MyAppWeb.MyAuthErrorHandler,
one_of: [~w(admin), ~w(read write)]
end
If the Authorization Header was verified, you'll be able to retrieve the current resource owner or access token.
ExOauth2Provider.Plug.current_access_token(conn) # access the token in the `:default` location
ExOauth2Provider.Plug.current_access_token(conn, :custom) # access the token in the `:custom` location if set as `:key` option in `plug ExOauth2Provider.Plug.VerifyHeader`
ExOauth2Provider.Plug.current_resource_owner(conn) # Access the loaded resource owner in the `:default` location
ExOauth2Provider.Plug.current_resource_owner(conn, :custom) # Access the loaded resource owner in the `:secret` location if set as `:key` option in `plug ExOauth2Provider.Plug.VerifyHeader`
You can add your own access token generator, as this example shows:
# config/config.exs
config :my_app, ExOauth2Provider,
access_token_generator: {AccessToken, :new}
defmodule AccessToken
def new(access_token) do
with_signer(%JWT.token{
resource_owner_id: access_token.resource_owner_id,
application_id: access_token.application.id,
scopes: access_token.scopes,
expires_in: access_token.expires_in,
created_at: access_token.created_at
}, hs256("my_secret"))
end
end
Remember to change the field type for the token
column in the oauth_access_tokens
table to accepts tokens larger than 255 characters.
You can add extra values to the response body.
# config/config.exs
config :my_app, ExOauth2Provider,
access_token_response_body_handler: {CustomResponse, :response}
defmodule CustomResponse
def response(response_body, access_token) do
Map.merge(response_body, %{user_id: access_token.resource_owner.id})
end
end
Remember to change the field type for the token
column in the oauth_access_tokens
table to accepts tokens larger than 255 characters.
You'll need to create the migration file and schema modules with the argument --binary-id
:
mix ex_oauth2_provider.install --binary-id
This library was made thanks to doorkeeper, guardian and authable, that gave the conceptual building blocks.
Thanks to Benjamin Schultzer for helping to refactor the code.
(The MIT License)
Copyright (c) 2017-2019 Dan Schultzer & the Contributors
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.