Conductor

Simple package for api authorization.

When is this package good?

when you need to restrict access to most endpoints when exposing some to third party developers
when you don't want to spam your controllers with plugs for every action
when you must respond according to existing permission system (e.g. scopes in jwt)

When is this package not good?

when you need authentication
when you need authorization for html pages
when you need advanced permissions management system

Installation

def deps do
  [{:conductor, "~> 0.2.0"}]
end

Conductor macro

Basically, this:

defmodule Controller do
  use Conductor # Important! It needs to be before use Phoenix.Controller
  use Phoenix.Controller

  def index(conn, _params),  do: #...

  def show(conn, _params),   do: #...

  @authorize scope: "scope1"
  def create(conn, _params)  do: #...

  @authorize scope: "scope2"
  def delete(conn, _params), do: #...
end

will be compiled to this:

defmodule Controller do
  use Conductor
  use Phoenix.Controller

  plug Conductor.Plugs.Authorize, ["scope1"] when action in [:create]
  plug Conductor.Plugs.Authorize, ["scope2"] when action in [:delete]
  plug Conductor.Plugs.Authorize, [] when not action in [:create, :delete]

  def index(conn, _params),  do: #...
  def show(conn, _params),   do: #...
  def create(conn, _params), do: #...
  def delete(conn, _params), do: #...
end

Root scope

You can register scope that will have full access everywhere

  config :conductor,
    root_scopes: ["admin"]

Adding scopes

  conn |> Plug.Conn.assign(:scopes, ["scope1, scope2"])

Public access

defmodule Router do
  pipeline :public do
    plug Conductor.Plugs.SkipAuthorization
  end

  scope "/public", MyApp do
    pipe_through [:public]

    get "/something", SomethingController, :something
  end
end

Authorization failures

To avoid confusion with random 403 response codes that come from nowhere, Conductor will raise error on authorization failure as default.

This can be changed by following config

  config :conductor,
    on_auth_failure: :send_resp

Example

  #config
  config :conductor,
    root_scopes: ["root_scope"],
    on_auth_failure: :send_resp

  #router
  pipeline :public do
    plug Conductor.Plugs.SkipAuthorization
  end

  scope "/", Example do
    get "/1", Controller, :action1
    get "/3", Controller, :action3
    get "/4", Controller, :action4
  end

  scope "/", Example do
    pipe_through [:public]

    get "/2", Controller, :action2
  end

  #conns
  conn1 = Phoenix.ConnTest.build_conn()
  conn2 = conn1 |> Plug.Conn.assign(:scopes, ["scope1", "scope2"])
  conn3 = conn1 |> Plug.Conn.assign(:scopes, ["root_scope"])

  #endpoints
  @authorize scope: "scope1"
  def action1(conn, _params), do: conn |> send_resp(200, "")

  @authorize scope: "scope2"
  def action2(conn, _params), do: conn |> send_resp(200, "")

  def action3(conn, _params), do: conn |> send_resp(200, "")

  @authorize scopes: ["other", "unused"]
  def action4(conn, _params), do: conn |> send_resp(200, "")

	conn1	conn2	conn3
action1	403	200	200
action2	200	200	200
action3	403	403	200
action4	403	403	200

Customization

Global

Failure response status code

  # config/config.exs
  config :conductor, :failure_status, 418

Failure response body

  # view
  defmodule MyApp.Web.ExampleView do
    use MyApp.Web, :view

    def render("403.json", _assigns) do
      %{message: "Forbidden"}
    end
  end

  # config/config.exs
  config :conductor, :failure_template, {MyApp.Web.ExampleView, "403.json"}

License

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.