Pow is a robust, modular, and extendable authentication and user management solution for Phoenix and Plug-based apps.
- User registration
- Session based authorization
- Per Endpoint/Plug configuration
- API token authorization
- Mnesia cache with automatic cluster healing
- Multitenancy
- User roles
- Extendable
- I18n
- And more
Add Pow to your list of dependencies in mix.exs:
defp deps do
[
# ...
{:pow, "~> 1.0.38"}
]
endRun mix deps.get to install it.
Umbrella project: Check out the umbrella project guide.
Install the necessary files:
mix pow.installThis will add the following files to your app:
LIB_PATH/users/user.ex
PRIV_PATH/repo/migrations/TIMESTAMP_create_users.exAnd also update the following files:
config/config.exs
WEB_PATH/endpoint.ex
WEB_PATH/router.exRun 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.
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.templatesThis 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.
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 PowEmailConfirmationThen 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.ControllerCallbacksUpdate 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
user_or_changeset
|> pow_changeset(attrs)
|> pow_extension_changeset(attrs)
end
endAdd 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
pow_routes()
pow_extension_routes()
end
# ...
endTemplates for extensions can be generated with:
mix pow.extension.phoenix.gen.templates --extension PowResetPassword --extension PowEmailConfirmationPlease follow the instructions in "Modify templates" to ensure that your custom templates will be used.
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: user.email, subject: subject, text: text, html: html}
end
def process(email) do
# Send email
Logger.debug("E-mail sent: #{inspect email}")
end
endUpdate config/config.ex with :mailer_backend key:
config :my_app, :pow,
# ...
mailer_backend: MyAppWeb.Pow.MailerThis 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.
Generate the template files:
mix pow.extension.phoenix.mailer.gen.templates --extension PowResetPassword --extension PowEmailConfirmationThis 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.
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.
Pow has three main groups of modules that each can be used individually, or in conjunction with each other:
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.
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.
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).
This module helps build extensions for Pow. There're three extension mix tasks to generate Ecto migrations and phoenix templates.
mix pow.extension.ecto.gen.migrationsmix pow.extension.phoenix.gen.templatesmix pow.extension.phoenix.mailer.gen.templatesPow 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:
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, user.id)
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
endThe 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:
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
endControllers 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:
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
endYou can add functions for before_process/4 (before the action happens) and before_respond/4 (before parsing the results from the action).
To test with authenticated users in your controller tests, you just have to assign the user to the conn in your setup callback:
setup %{conn: conn} do
user = %User{email: "[email protected]"}
conn = Pow.Plug.assign_current_user(conn, user, otp_app: :my_app)
{:ok, conn: conn}
endAll templates can be generated and modified to use your Gettext module.
For flash messages, you can create the following module:
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.")
endAdd messages_backend: MyAppWeb.Pow.Messages to your configuration. You can find all the messages in Pow.Phoenix.Messages and [Pow Extension].Phoenix.Messages.
You can customize callback routes by creating the following module:
defmodule MyAppWeb.Pow.Routes do
use Pow.Phoenix.Routes
use MyAppWeb, :verified_routes
def after_sign_in_path(conn), do: ~p"/home"
endAdd routes_backend: MyAppWeb.Pow.Routes to your configuration. You can find all the routes in Pow.Phoenix.Routes.
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:
config :pow, Pow.Ecto.Schema.Password, iterations: 1You can change the password hashing function easily. For example, this is how you use comeonin with Argon2:
defmodule MyApp.Users.User do
use Ecto.Schema
use Pow.Ecto.Schema,
password_hash_verify: {&Argon2.hash_pwd_salt/1,
&Argon2.verify_pass/2}
# ...
endYou 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:
<.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).
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.
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:
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
# ...
endUpdate config/config.ex with :cache_store_backend key:
config :my_app, :pow,
# ...
cache_store_backend: Pow.Store.Backend.MnesiaCacheRemember 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.
Will halt connection if no current user is not present in assigns. Expects an :error_handler option.
Will halt connection if a current user is present in assigns. Expects an :error_handler option.
See security practices.
PowAssent - Multi-provider support for Pow with strategies for Twitter, Github, Google, Facebook and more
Please read CONTRIBUTING.md.
(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.
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