OAuth2 (Client)
An Elixir OAuth2 Client
Install
# mix.exs
def application do
# Add the application to your list of applications.
# This will ensure that it will be included in a release.
[applications: [:logger, :oauth2]]
end
defp deps do
# Add the dependency
[{:oauth2, "~> 2.0"}]
end
Configure a serializer
This library can be configured to handle encoding and decoding requests and
responses automatically based on the accept
and/or content-type
headers.
If you need to handle various MIME types, you can simply register serializers like so:
OAuth2.Client.put_serializer(client, "application/vnd.api+json", Jason)
OAuth2.Client.put_serializer(client, "application/xml", MyApp.Parsers.XML)
The modules are expected to export encode!/1
and decode!/1
.
defmodule MyApp.Parsers.XML do
def encode!(data), do: # ...
def decode!(binary), do: # ...
end
Please see the documentation for OAuth2.Serializer for more details.
Debug mode
Sometimes it's handy to see what's coming back from the response when getting a token. You can configure OAuth2 to output the response like so:
config :oauth2, debug: true
Usage
Current implemented strategies:
- Authorization Code
- Password
- Client Credentials
Authorization Code Flow (AuthCode Strategy)
# Initialize a client with client_id, client_secret, site, and redirect_uri.
# The strategy option is optional as it defaults to `OAuth2.Strategy.AuthCode`.
client = OAuth2.Client.new([
strategy: OAuth2.Strategy.AuthCode, #default
client_id: "client_id",
client_secret: "abc123",
site: "https://auth.example.com",
redirect_uri: "https://example.com/auth/callback"
])
# Generate the authorization URL and redirect the user to the provider.
OAuth2.Client.authorize_url!(client)
# => "https://auth.example.com/oauth/authorize?client_id=client_id&redirect_uri=https%3A%2F%2Fexample.com%2Fauth%2Fcallback&response_type=code"
# Use the authorization code returned from the provider to obtain an access token.
client = OAuth2.Client.get_token!(client, code: "someauthcode")
# Use the access token to make a request for resources
resource = OAuth2.Client.get!(client, "/api/resource").body
Client Credentials Flow
Getting an initial access token:
# Initializing a client with the strategy `OAuth2.Strategy.ClientCredentials`
client = OAuth2.Client.new([
strategy: OAuth2.Strategy.ClientCredentials,
client_id: "client_id",
client_secret: "abc123",
site: "https://auth.example.com"
])
# Request a token from with the newly created client
# Token will be stored inside the `%OAuth2.Client{}` struct (client.token)
client = OAuth2.Client.get_token!(client)
# client.token contains the `%OAuth2.AccessToken{}` struct
# raw access token
access_token = client.token.access_token
Refreshing an access token:
# raw refresh token - use a client with `OAuth2.Strategy.Refresh` for refreshing the token
refresh_token = client.token.refresh_token
refresh_client = OAuth2.Client.new([
strategy: OAuth2.Strategy.Refresh,
client_id: "client_id",
client_secret: "abc123",
site: "https://auth.example.com",
params: %{"refresh_token" => refresh_token}
])
# refresh_client.token contains the `%OAuth2.AccessToken{}` struct again
refresh_client = OAuth2.Client.get_token!(refresh_client)
Write Your Own Strategy
Here's an example strategy for GitHub:
defmodule GitHub do
use OAuth2.Strategy
# Public API
def client do
OAuth2.Client.new([
strategy: __MODULE__,
client_id: System.get_env("GITHUB_CLIENT_ID"),
client_secret: System.get_env("GITHUB_CLIENT_SECRET"),
redirect_uri: "http://myapp.com/auth/callback",
site: "https://api.github.com",
authorize_url: "https://github.com/login/oauth/authorize",
token_url: "https://github.com/login/oauth/access_token"
])
|> OAuth2.Client.put_serializer("application/json", Jason)
end
def authorize_url! do
OAuth2.Client.authorize_url!(client(), scope: "user,public_repo")
end
# you can pass options to the underlying http library via `opts` parameter
def get_token!(params \\ [], headers \\ [], opts \\ []) do
OAuth2.Client.get_token!(client(), params, headers, opts)
end
# Strategy Callbacks
def authorize_url(client, params) do
OAuth2.Strategy.AuthCode.authorize_url(client, params)
end
def get_token(client, params, headers) do
client
|> put_header("accept", "application/json")
|> OAuth2.Strategy.AuthCode.get_token(params, headers)
end
end
Here's how you'd use the example GitHub strategy:
Generate the authorize URL and redirect the client for authorization.
GitHub.authorize_url!
Capture the code
in your callback route on your server and use it to obtain an access token.
client = GitHub.get_token!(code: code)
Use the access token to access desired resources.
user = OAuth2.Client.get!(client, "/user").body
# Or
case OAuth2.Client.get(client, "/user") do
{:ok, %OAuth2.Response{body: user}} ->
user
{:error, %OAuth2.Response{status_code: 401, body: body}} ->
Logger.error("Unauthorized token")
{:error, %OAuth2.Error{reason: reason}} ->
Logger.error("Error: #{inspect reason}")
end
Examples
License
The MIT License (MIT)
Copyright (c) 2015 Sonny Scroggin
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.