11. Authentication traits#

11.1. authDefinition trait#

Summary
A meta-trait that marks a trait as an authentication scheme. Traits that are marked with this trait are applied to service shapes to indicate how a client can authenticate with the service.
Trait selector
[trait|trait]
Value type

An object with the following properties:

Property Type Description
traits [Shape ID] List of shape IDs that auth scheme implementations MUST understand in order to successfully use the scheme. Each shape MUST exist and MUST be a trait. Code generators SHOULD ensure that they support each listed trait.

Every operation in the closure of a service is expected to support the authentication schemes applied to a service unless the service or operation is marked with the auth trait, which is used to change the set of supported authentication schemes.

The following example defines a service that supports both httpBasicAuth and the hypothetical fooExample authentication scheme.

$version: "2"
namespace smithy.example

@authDefinition
@trait(selector: "service")
structure fooExample {}

@fooExample
@httpBasicAuth
service WeatherService {
    version: "2017-02-11"
}

Because authentication scheme definitions are just specialized shapes, they can also support configuration settings.

$version: "2"
namespace smithy.example

@authDefinition
@trait(selector: "service")
structure algorithmAuth {
    algorithm: AlgorithmAuthAlgorithm
}

@private
enum AlgorithmAuthAlgorithm {
    SHA2 = "SHA-2"
}

@algorithmAuth(algorithm: "SHA-2")
service WeatherService {
    version: "2017-02-11"
}

11.2. httpBasicAuth trait#

Summary
Indicates that a service supports HTTP Basic Authentication as defined in RFC 2617.
Trait selector
service
Value type
Annotation trait.
@httpBasicAuth
service WeatherService {
    version: "2017-02-11"
}

11.3. httpDigestAuth trait#

Summary
Indicates that a service supports HTTP Digest Authentication as defined in RFC 2617.
Trait selector
service
Value type
Annotation trait.
@httpDigestAuth
service WeatherService {
    version: "2017-02-11"
}

11.4. httpBearerAuth trait#

Summary
Indicates that a service supports HTTP Bearer Authentication as defined in RFC 6750.
Trait selector
service
Value type
Annotation trait.
@httpBearerAuth
service WeatherService {
    version: "2017-02-11"
}

11.5. httpApiKeyAuth trait#

Summary
Indicates that a service supports HTTP-specific authentication using an API key sent in a header or query string parameter.
Trait selector
service
Value type
Object

The httpApiKeyAuth trait is an object that supports the following properties:

Property Type Description
name string Required. Defines the name of the HTTP header or query string parameter that contains the API key.
in string Required. Defines the location of where the key is serialized. This value can be set to header or query.
scheme string Defines the security scheme to use on the Authorization header value This can only be set if the "in" property is set to header.

The following example defines a service that accepts an API key in the "X-Api-Key" HTTP header:

@httpApiKeyAuth(name: "X-Api-Key", in: "header")
service WeatherService {
    version: "2017-02-11"
}

The following example defines a service that uses an API key auth scheme through the HTTP Authorization header:

@httpApiKeyAuth(scheme: "ApiKey", name: "Authorization", in: "header")
service WeatherService {
    version: "2017-02-11"
}

11.6. optionalAuth trait#

Summary
Indicates that an operation MAY be invoked without authentication, regardless of any authentication traits applied to the operation.
Trait selector
operation
Value type
Annotation trait.

The following example defines a service that uses HTTP digest authentication, and bound to the service is an operation that supports unauthenticated access.

@httpDigestAuth
service WeatherService {
    version: "2017-02-11"
    operations: [PingServer]
}

@optionalAuth
operation PingServer {}

The following example defines an operation that does not support any authentication. This kind of operation does not require the optionalAuth trait.

@auth([])
operation SomeUnauthenticatedOperation {}

11.7. auth trait#

Summary
Defines the priority ordered authentication schemes supported by a service or operation. When applied to a service, it defines the default authentication schemes of every operation in the service. When applied to an operation, it defines the list of all authentication schemes supported by the operation, overriding any auth trait specified on a service.
Trait selector

:is(service, operation)

Service or operation shapes

Value type
This trait contains a priority ordered list of unique string values that reference authentication scheme shape IDs defined on a service shape.

Operations that are not annotated with the auth trait inherit the auth trait of the service they are bound to. If the operation is not annotated with the auth trait, and the service it is bound to is also not annotated with the auth trait, then the operation is expected to support each of the authentication scheme traits applied to the service. Each entry in the auth trait is a shape ID that MUST refer to an authentication scheme trait applied to the service in which it is bound.

The following example defines all combinations in which auth can be applied to services and operations:

  • ServiceWithNoAuthTrait does not use the auth trait and binds two operations:
    • OperationA is not annotated with the auth trait and inherits all of the authentication scheme applied to the service.
    • OperationB is annotated with the auth trait and defines an explicit list of authentication schemes.
  • ServiceWithAuthTrait is annotated with the auth trait and binds two operations:
    • OperationC is not annotated with the auth trait and inherits all of the authentication schemes applied via the auth trait on the service.
    • OperationD is annotated with the auth trait and defines an explicit list of authentication schemes.
@httpBasicAuth
@httpDigestAuth
@httpBearerAuth
service ServiceWithNoAuthTrait {
    version: "2020-01-29"
    operations: [
        OperationA
        OperationB
    ]
}

// This operation does not have the @auth trait and is bound to a service
// without the @auth trait. The effective set of authentication schemes it
// supports are: httpBasicAuth, httpDigestAuth and httpBearerAuth
operation OperationA {}

// This operation does have the @auth trait and is bound to a service
// without the @auth trait. The effective set of authentication schemes it
// supports are: httpDigestAuth.
@auth([httpDigestAuth])
operation OperationB {}

@httpBasicAuth
@httpDigestAuth
@httpBearerAuth
@auth([httpBasicAuth, httpDigestAuth])
service ServiceWithAuthTrait {
    version: "2020-01-29"
    operations: [
        OperationC
        OperationD
    ]
}

// This operation does not have the @auth trait and is bound to a service
// with the @auth trait. The effective set of authentication schemes it
// supports are: httpBasicAuth, httpDigestAuth
operation OperationC {}

// This operation has the @auth trait and is bound to a service
// with the @auth trait. The effective set of authentication schemes it
// supports are: httpBearerAuth
@auth([httpBearerAuth])
operation OperationD {}

The following auth trait is invalid because it references an authentication scheme trait that is not applied to the service:

@httpDigestAuth
@auth([httpBasicAuth]) // <-- Invalid!
service InvalidExample {
    version: "2017-02-11"
}

The following operation auth trait is invalid because it references an authentication scheme trait that is not applied to the service:

@httpDigestAuth
service InvalidExample {
    version: "2017-02-11",
    operations: [OperationA]
}

@auth([httpBasicAuth]) // <-- Invalid!
operation OperationA {}