documentation/dsls/DSL-AshAuthentication.md

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# DSL: AshAuthentication

AshAuthentication provides a turn-key authentication solution for folks using
[Ash](https://www.ash-hq.org/).

## Usage

This package assumes that you have [Ash](https://ash-hq.org/) installed and
configured.  See the Ash documentation for details.

Once installed you can easily add support for authentication by configuring
the `AshAuthentication` extension on your resource:

```elixir
defmodule MyApp.Accounts.User do
  use Ash.Resource,
    extensions: [AshAuthentication],
    domain: MyApp.Accounts

  attributes do
    uuid_primary_key :id
    attribute :email, :ci_string, allow_nil?: false
    attribute :hashed_password, :string, allow_nil?: false, sensitive?: true
  end

  authentication do
    strategies do
      password :password do
        identity_field :email
        hashed_password_field :hashed_password
      end
    end
  end

  identities do
    identity :unique_email, [:email]
  end
end
```

If you plan on providing authentication via the web, then you will need to
define a plug using `AshAuthentication.Plug` which builds a `Plug.Router` that
routes incoming authentication requests to the correct provider and provides
callbacks for you to manipulate the conn after success or failure.

If you're using AshAuthentication with Phoenix, then check out
[`ash_authentication_phoenix`](https://github.com/team-alembic/ash_authentication_phoenix)
which provides route helpers, a controller abstraction and LiveView components
for easy set up.

## Authentication Strategies

Currently supported strategies:

1. `AshAuthentication.Strategy.Password`
   - authenticate users against your local database using a unique identity
   (such as username or email address) and a password.
2. `AshAuthentication.Strategy.OAuth2`
   - authenticate using local or remote [OAuth 2.0](https://oauth.net/2/) compatible services.
   - also includes:
     - `AshAuthentication.Strategy.Apple`
     - `AshAuthentication.Strategy.Auth0`
     - `AshAuthentication.Strategy.Github`
     - `AshAuthentication.Strategy.Google`
     - `AshAuthentication.Strategy.Oidc`
     - `AshAuthentication.Strategy.Slack`
3. `AshAuthentication.Strategy.MagicLink`
   - authenticate by sending a single-use link to the user.

### HTTP client settings

Most of the authentication strategies based on `OAuth2` wrap the [`assent`](https://hex.pm/packages/assent) package.

If you needs to customize the behavior of the http client used by `assent`, define a custom `http_adapter` in the
application settings:

`config :ash_authentication, :http_adapter, {Assent.HTTPAdapter.Finch, supervisor: MyApp.CustomFinch}`

See [`assent's documentation`](https://hexdocs.pm/assent/README.html#http-client) for more details on the supported
http clients and their configuration.

## Add-ons

Add-ons are like strategies, except that they don't actually provide
authentication - they just provide features adjacent to authentication.
Current add-ons:

1. `AshAuthentication.AddOn.Confirmation`
   - allows you to force the user to confirm changes using a confirmation
     token (eg. sending a confirmation email when a new user registers).

## Supervisor

Some add-ons or strategies may require processes to be started which manage
their state over the lifetime of the application (eg periodically deleting
expired token revocations).  Because of this you should add
`{AshAuthentication.Supervisor, otp_app: :my_app}` to your application's
supervision tree.  See [the Elixir
docs](https://hexdocs.pm/elixir/Application.html#module-the-application-callback-module)
for more information.


## authentication
Configure authentication for this resource

### Nested DSLs
 * [tokens](#authentication-tokens)
 * [strategies](#authentication-strategies)
 * [add_ons](#authentication-add_ons)





### Options

| Name | Type | Default | Docs |
|------|------|---------|------|
| [`subject_name`](#authentication-subject_name){: #authentication-subject_name } | `atom` |  | The subject name is used anywhere that a short version of your resource name is needed.  Must be unique system-wide and will be inferred from the resource name by default (ie `MyApp.Accounts.User` -> `user`). |
| [`domain`](#authentication-domain){: #authentication-domain } | `module` |  | The name of the Ash domain to use to access this resource when doing anything authentication related. |
| [`get_by_subject_action_name`](#authentication-get_by_subject_action_name){: #authentication-get_by_subject_action_name } | `atom` | `:get_by_subject` | The name of the read action used to retrieve records. If the action doesn't exist, one will be generated for you. |
| [`select_for_senders`](#authentication-select_for_senders){: #authentication-select_for_senders } | `list(atom)` |  | A list of fields that we will ensure are selected whenever a sender will be invoked.  Defaults to `[:email]` if there is an `:email` attribute on the resource, and `[]` otherwise. |


## authentication.tokens
Configure JWT settings for this resource






### Options

| Name | Type | Default | Docs |
|------|------|---------|------|
| [`token_resource`](#authentication-tokens-token_resource){: #authentication-tokens-token_resource .spark-required} | `module \| false` |  | The resource used to store token information, such as in-flight confirmations, revocations, and if `store_all_tokens?` is enabled, authentication tokens themselves. |
| [`enabled?`](#authentication-tokens-enabled?){: #authentication-tokens-enabled? } | `boolean` | `false` | Should JWTs be generated by this resource? |
| [`store_all_tokens?`](#authentication-tokens-store_all_tokens?){: #authentication-tokens-store_all_tokens? } | `boolean` | `false` | Store all tokens in the `token_resource`. See the [tokens guide](/documentation/topics/tokens.md) for more. |
| [`require_token_presence_for_authentication?`](#authentication-tokens-require_token_presence_for_authentication?){: #authentication-tokens-require_token_presence_for_authentication? } | `boolean` | `false` | Require a locally-stored token for authentication. See the [tokens guide](/documentation/topics/tokens.md) for more. |
| [`signing_algorithm`](#authentication-tokens-signing_algorithm){: #authentication-tokens-signing_algorithm } | `String.t` | `"HS256"` | The algorithm to use for token signing. Available signing algorithms are; EdDSA, Ed448ph, Ed448, Ed25519ph, Ed25519, PS512, PS384, PS256, ES512, ES384, ES256, RS512, RS384, RS256, HS512, HS384 and HS256. |
| [`token_lifetime`](#authentication-tokens-token_lifetime){: #authentication-tokens-token_lifetime } | `pos_integer \| {pos_integer, :days \| :hours \| :minutes \| :seconds}` | `{14, :days}` | How long a token should be valid. See [the tokens guide](/documentation/topics/tokens.md) for more. |
| [`signing_secret`](#authentication-tokens-signing_secret){: #authentication-tokens-signing_secret } | `(any, any -> any) \| module \| String.t` |  | The secret used to sign tokens.  Takes either a module which implements the `AshAuthentication.Secret` behaviour, a 2 arity anonymous function or a string. |




## authentication.strategies
Configure authentication strategies on this resource







## authentication.add_ons
Additional add-ons related to, but not providing authentication












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