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Pow is a robust, modular, and extendable authentication and user management solution for Phoenix and Plug-based apps.





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

defp deps do
    # ...
    {:pow, "~> 1.0.29"}

Run mix deps.get to install it.


Getting started


Phoenix app

Umbrella project: Check out the umbrella project guide.

Install the necessary files:

mix pow.install

This will add the following files to your app:


And also update the following files:


Run migrations with mix setup, start the server with mix phx.server, and you can now visit http://localhost:4000/registration/new to create a user.


Modify templates

By default, Pow exposes as few files as possible.

If you wish to modify the templates, you can generate them using:

mix pow.phoenix.gen.templates

This will also add web_module: MyAppWeb to the configuration in config/config.exs.



Pow is made so it's easy to extend the functionality with your own complimentary library. The following extensions are included in this library:

Check out the "Other libraries" section for other extensions.


Add extensions support

To keep it easy to understand and configure Pow, you'll have to enable the extensions yourself.

Let's install the PowResetPassword and PowEmailConfirmation extensions.

First, install extension migrations by running:

mix pow.extension.ecto.gen.migrations --extension PowResetPassword --extension PowEmailConfirmation

Then run the migrations with mix ecto.migrate. Now, update config/config.ex with the :extensions and :controller_callbacks key:

config :my_app, :pow,
  user: MyApp.Users.User,
  repo: MyApp.Repo,
  extensions: [PowResetPassword, PowEmailConfirmation],
  controller_callbacks: Pow.Extension.Phoenix.ControllerCallbacks

Update LIB_PATH/users/user.ex with the extensions:

defmodule MyApp.Users.User do
  use Ecto.Schema
  use Pow.Ecto.Schema
  use Pow.Extension.Ecto.Schema,
    extensions: [PowResetPassword, PowEmailConfirmation]

  # ...

  def changeset(user_or_changeset, attrs) do
    |> pow_changeset(attrs)
    |> pow_extension_changeset(attrs)

Add Pow extension routes to WEB_PATH/router.ex:

defmodule MyAppWeb.Router do
  use MyAppWeb, :router
  use Pow.Phoenix.Router
  use Pow.Extension.Phoenix.Router,
    extensions: [PowResetPassword, PowEmailConfirmation]

  # ...

  scope "/" do
    pipe_through :browser


  # ...

Modify extension templates

Templates for extensions can be generated with:

mix pow.extension.phoenix.gen.templates --extension PowResetPassword --extension PowEmailConfirmation

Please follow the instructions in "Modify templates" to ensure that your custom templates will be used.


Mailer support

Many extensions require a mailer to have been set up. Let's create a mailer mock module in WEB_PATH/mails/pow/mailer.ex:

defmodule MyAppWeb.Pow.Mailer do
  use Pow.Phoenix.Mailer
  require Logger

  def cast(%{user: user, subject: subject, text: text, html: html, assigns: _assigns}) do
    # Build email struct to be used in `process/1`

    %{to:, subject: subject, text: text, html: html}

  def process(email) do
    # Send email

    Logger.debug("E-mail sent: #{inspect email}")

Update config/config.ex with :mailer_backend key:

config :my_app, :pow,
  # ...
  mailer_backend: MyAppWeb.Pow.Mailer

This mailer module will only output the mail to your log, so you can e.g. try out the reset password and email confirmation links. You should integrate the Pow mailer with your actual mailer system. For Swoosh or Bamboo integration, check out the Configuring mailer guide.

Modify mailer templates

Generate the template files:

mix pow.extension.phoenix.mailer.gen.templates --extension PowResetPassword --extension PowEmailConfirmation

This will generate template files in the WEB_PATH/mails/ directory. This will also add the necessary mail/0 macro to WEB_PATH/my_app_web.ex and update the pow config with `web_mailer_module: MyAppWeb. ## Configuration Pow is built to be modular, and easy to configure. The configuration is passed to function calls as well as plug options, and they will take priority over any environment configuration. It's ideal in case you got an umbrella app with multiple separate user domains. The easiest way to use Pow with Phoenix is to use a :otp_app in function calls and set the app environment configuration. It will keep a persistent fallback configuration that you configure in one place. ### Module groups Pow has three main groups of modules that each can be used individually, or in conjunction with each other: #### Pow.Plug This group will handle the plug connection. The configuration will be assigned to conn.private[:pow_config] and passed through the controller to the users' context module. The Plug module has functions to authenticate, create, update, and delete users, and will generate/renew the session automatically. #### Pow.Ecto This group contains all modules related to the Ecto based user schema and context. By default, Pow will use the Pow.Ecto.Context module to authenticate, create, update and delete users with lookups to the database. However, it's straightforward to extend or write your custom user context. You can do this by setting the :users_context configuration key. #### Pow.Phoenix This group contains the controllers and templates for Phoenix. You only need to set the (session) plug in endpoint.ex and add the routes to router.ex. Templates are not generated by default, instead, the compiled templates in Pow are used. You can generate the templates used by running mix pow.phoenix.gen.templates. You can also customize flash messages and callback routes by creating your own using :messages_backend and :routes_backend. The registration and session controllers can be changed with your customized versions too, but since the routes are built on compile time, you'll have to set them up in router.ex with :pow namespace. For minor pre/post-processing of requests, you can use the :controller_callbacks option. It exists to make it easier to modify flow with extensions (e.g., send a confirmation email upon user registration). ### Pow.Extension This module helps build extensions for Pow. There're three extension mix tasks to generate Ecto migrations and phoenix templates. bash mix pow.extension.ecto.gen.migrations bash mix pow.extension.phoenix.gen.templates bash mix pow.extension.phoenix.mailer.gen.templates ### Authorization plug Pow ships with a session plug module. You can easily switch it out with a different one. As an example, here's how you do that with Phoenix.Token: elixir defmodule MyAppWeb.Pow.Plug do use Pow.Plug.Base @session_key :pow_user_token @salt "user salt" @max_age 86400 def fetch(conn, config) do conn = Plug.Conn.fetch_session(conn) token = Plug.Conn.get_session(conn, @session_key) MyAppWeb.Endpoint |> Phoenix.Token.verify(@salt, token, max_age: @max_age) |> maybe_load_user(conn) end defp maybe_load_user({:ok, user_id}, conn), do: {conn, MyApp.Repo.get(User, user_id)} defp maybe_load_user({:error, _any}, conn), do: {conn, nil} def create(conn, user, config) do token = Phoenix.Token.sign(MyAppWeb.Endpoint, @salt, conn = conn |> Plug.Conn.fetch_session() |> Plug.Conn.put_session(@session_key, token) {conn, user} end def delete(conn, config) do conn |> Plug.Conn.fetch_session() |> Plug.Conn.delete_session(@session_key) end end defmodule MyAppWeb.Endpoint do # ... plug MyAppWeb.Pow.Plug, otp_app: :my_app end ### Ecto changeset The user module has a fallback changeset/2 function. If you want to add custom validations, you can use the pow_changeset/2 function like so: elixir defmodule MyApp.Users.User do use Ecto.Schema use Pow.Ecto.Schema schema "users" do field :custom, :string pow_user_fields() timestamps() end def changeset(user_or_changeset, attrs) do user_or_changeset |> pow_changeset(attrs) |> Ecto.Changeset.cast(attrs, [:custom]) |> Ecto.Changeset.validate_required([:custom]) end end ### Phoenix controllers Controllers in Pow are very slim and consists of just one Pow.Plug function call with response functions. If you wish to change the flow of the Pow.Phoenix.RegistrationController and Pow.Phoenix.SessionController, the best way is to create your own and modify router.ex. However, to make it easier to integrate extension, you can add callbacks to the controllers that do some light pre/post-processing of the request: elixir defmodule MyCustomExtension.Phoenix.ControllerCallbacks do use Pow.Extension.Phoenix.ControllerCallbacks.Base def before_respond(Pow.Phoenix.RegistrationController, :create, {:ok, user, conn}, _config) do # send email {:ok, user, conn} end end You can add functions for before_process/4 (before the action happens) and before_respond/4 (before parsing the results from the action). #### Testing with authenticated users To test with authenticated users in your controller tests, you just have to assign the user to the conn in your setup callback: elixir setup %{conn: conn} do user = %User{email: ""} conn = Pow.Plug.assign_current_user(conn, user, otp_app: :my_app) {:ok, conn: conn} end ### I18n All templates can be generated and modified to use your Gettext module. For flash messages, you can create the following module: elixir defmodule MyAppWeb.Pow.Messages do use Pow.Phoenix.Messages use Pow.Extension.Phoenix.Messages, extensions: [PowResetPassword] import MyAppWeb.Gettext def user_not_authenticated(_conn), do: gettext("You need to sign in to see this page.") # Message functions for extensions has to be prepended with the snake cased # extension name. So the `email_has_been_sent/1` function from # `PowResetPassword` is written as `pow_reset_password_email_has_been_sent/1` # in your messages module. def pow_reset_password_email_has_been_sent(_conn), do: gettext("An email with reset instructions has been sent to you. Please check your inbox.") end Add messages_backend: MyAppWeb.Pow.Messages to your configuration. You can find all the messages in Pow.Phoenix.Messages and [Pow Extension].Phoenix.Messages. ### Callback routes You can customize callback routes by creating the following module: elixir defmodule MyAppWeb.Pow.Routes do use Pow.Phoenix.Routes use MyAppWeb, :verified_routes def after_sign_in_path(conn), do: ~p"/home" end Add routes_backend: MyAppWeb.Pow.Routes to your configuration. You can find all the routes in Pow.Phoenix.Routes. ### Password hashing function Pow.Ecto.Schema.Password is used to hash and verify with Pbkdf2. It's highly recommended to lower the iterations count in your test environment to speed up your tests: elixir config :pow, Pow.Ecto.Schema.Password, iterations: 1 You can change the password hashing function easily. For example, this is how you use comeonin with Argon2: elixir defmodule MyApp.Users.User do use Ecto.Schema use Pow.Ecto.Schema, password_hash_methods: {&Argon2.hash_pwd_salt/1, &Argon2.verify_pass/2} # ... end ### Current user and sign out link You can use Pow.Plug.current_user/1 to fetch the current user from the connection. This can be used to show the sign in or sign out links in your Phoenix template: elixir <.link :if={Pow.Plug.current_user(@conn)} href={~p"/session"} method="delete">Sign out</.link> <.link :if={is_nil Pow.Plug.current_user(@conn)} navigate={~p"/registration/new"}>Registration</.link> <.link :if={is_nil Pow.Plug.current_user(@conn)} navigate={~p"/session/new"}>Sign In</.link> The current user can also be fetched by using the template assigns set in the configuration with :current_user_assigns_key (defaults to @current_user). ## Plugs ### Pow.Plug.Session Enables session-based authorization. The user struct will be collected from a cache store through a GenServer using a unique token generated for the session. The token will be reset every time the authorization level changes (handled by Pow.Plug) or after a certain interval (default 15 minutes). The user struct fetched can be out of sync with the database if the row in the database is updated by actions outside Pow. In this case, it's recommended to add a plug that reloads the user struct and reassigns it to the connection. Custom metadata can be set for the session by assigning a private :pow_session_metadata key in the conn. Read the Pow.Plug.Session module docs for more details. #### Cache store By default Pow.Store.Backend.EtsCache is started automatically and can be used in development and test environment. For a production environment, you should use a distributed, persistent cache store. Pow makes this easy with Pow.Store.Backend.MnesiaCache. To start MnesiaCache in your Phoenix app, add it to your application.ex supervisor: elixir defmodule MyApp.Application do use Application def start(_type, _args) do children = [ MyApp.Repo, MyAppWeb.Endpoint, Pow.Store.Backend.MnesiaCache # # Or in a distributed system: # {Pow.Store.Backend.MnesiaCache, extra_db_nodes: {Node, :list, []}}, # Pow.Store.Backend.MnesiaCache.Unsplit # Recover from netsplit ] opts = [strategy: :one_for_one, name: MyAppWeb.Supervisor] Supervisor.start_link(children, opts) end # ... end Update config/config.ex with :cache_store_backend key: elixir config :my_app, :pow, # ... cache_store_backend: Pow.Store.Backend.MnesiaCache Remember to add :mnesia to your :extra_applications so it'll be available for your release build. Mnesia will write files to the current working directory. The path can be changed with config :mnesia, dir: '/path/to/dir'. The MnesiaCache requires write access. If you've got a read-only file system you should take a look at the Redis cache backend store guide. ### Pow.Plug.RequireAuthenticated Will halt connection if no current user is not present in assigns. Expects an :error_handler option. ### Pow.Plug.RequireNotAuthenticated Will halt connection if a current user is present in assigns. Expects an :error_handler option. ## Pow security practices See security practices. ## Other libraries PowAssent - Multi-provider support for Pow with strategies for Twitter, Github, Google, Facebook and more ## Contributing Please read ## LICENSE (The MIT License) Copyright (c) 2018-2019 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.