# Security

## Authorization Configuration

### `d:Ash.Domain.Dsl.authorization|require_actor?`

Requires that an actor is set for all requests.

Important: `nil` is still a valid actor, so this won't prevent providing `actor: nil`.


### `d:Ash.Domain.Dsl.authorization|authorize`

When to run authorization for a given request.

- `:by_default` sets `authorize?: true` if the `authorize?` option was not set (so it can be set to `false`). This is the default.
- `:always` forces `authorize?: true` on all requests to the domain.
- `:when_requested` sets `authorize?: true` whenever an actor is set or `authorize?: true` is explicitly passed. This is the default behavior.


## Sensitive Attributes

Using `sensitive? true` will cause the argument to be `** Redacted **` from the resource when logging or inspecting. In filter statements, any value used in the same expression as a sensitive attribute will also be redacted. For example, you might see: `email == "** Redacted **"` in a filter statement if `email` is marked as sensitive.

## Authorization

Authorization in Ash is done via authorizers. Generally, you won't need to create your own  authorizer, as the builtin policy authorizer `Ash.Policy.Authorizer` should work well for any use case. Authorization is performed with a given actor and a query or changeset.

### Actors

An actor is the "entity performing the action". This is generally a user, but could potentially be an organization, a group, whatever makes sense for your use case. By default, when using Ash in code, authorization does not happen.

```elixir
# Does not perform authorization
Ash.read!(User)
```

However, if you either 1. provide an actor or 2. use the `authorize?: true` option, then authorization will happen.

```elixir
# Authorize with a `nil` actor (which is valid, i.e if no one is logged in and they are trying to list users)
Ash.read!(User, actor: nil)

# Authorize with a `nil` actor
Ash.read!(User, authorize?: true)

# Authorize with an actor
Ash.read!(User, actor: current_user)

# Authorize with an actor, but being explicit
Ash.read!(User, actor: current_user, authorize?: true)

# Skip authorization, but set an actor. The actor can be used in other things than authorization
# so this may make sense depending on what you are doing.
Ash.read!(User, actor: current_user, authorize?: false)
```

#### Where to set the actor

When setting an actor, if you are building a query or changeset, you should do so at the time that you call the various `for_*` functions. This makes the actor available in the context of any change that is run. For example:

```elixir
# DO THIS
Resource
|> Ash.Query.for_read(:read, input, actor: current_user)
|> Ash.read()

# DON'T DO THIS
Resource
|> Ash.Query.for_read(:read, input)
|> Ash.read(actor: current_user)
```

The second option "works" in most cases, but not all, because some `change`s might need to know the actor and will instead get `nil`.