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Authentication

Configure

Authentication can be configured using the @useAuth decorator on a service namespace, sub-namespace, interface or operation.

The @useAuth decorator takes as input the security scheme to apply for all operations contained in the type. If another @useAuth was specified on a parent type, the new one will override the value of the parent. See application hierarchy for more details.

The input to @useAuth can be:

  • A single security scheme (see options here).

    @useAuth(Auth1)

  • A tuple of security schemes. This creates a security group and means all the security schemes in the group must be used together to authenticate this service.

    // Use BOTH Auth1 AND Auth2
    @useAuth([Auth1, Auth2])

  • A union of security schemes. This means one of the security schemes must be used to authenticate this service.

    // Use EITHER Auth1 OR Auth2
    @useAuth(Auth1 | Auth2)

  • A union of security schemes and tuples representing security groups. This means one of the security groups or security schemes must be used to authenticate this service.

    // Use EITHER (Auth1 AND Auth2) OR Auth3
    @useAuth([Auth1, Auth2] | Auth3)

Available security schemes

Security scheme models can be found in the TypeSpec HTTP library

Http Auths

These are authentication methods that use the Authorization header. They follow the format Authorization: <auth-scheme> <authorization-parameters>

  • auth-scheme: The authentication scheme that defines how the credentials are encoded.
  • authorization-parameters: Scheme-dependent parameters.

TypeSpec HTTP defines 2 commonly used authentication schemes:

  • BasicAuth (scheme: Basic)
  • BearerAuth (scheme: Bearer)

BasicAuth

Basic authentication is a simple authentication scheme built into the HTTP protocol. The client sends HTTP requests with the Authorization header that contains the word Basic followed by a space and a base64-encoded string in the format username:password. For example, to authorize as demo / p@55w0rd the client would send:

Authorization: Basic ZGVtbzpwQDU1dzByZA==

In TypeSpec, you would use:

@useAuth(BasicAuth)

BearerAuth

Bearer authentication (also called token authentication) is an HTTP authentication scheme that involves security tokens called bearer tokens. The name “Bearer authentication” can be understood as “give access to the bearer of this token.” The bearer token is a cryptic string, usually generated by the server in response to a login request. The client must send this token in the Authorization header when making requests to protected resources:

Authorization: Bearer <token>

In TypeSpec, you would use:

@useAuth(BearerAuth)

Custom scheme

If your service uses a custom authentication scheme, you can define it as well. For example, if you use a SharedKey authentication scheme that would result in the following header:

Authorization: SharedKey <key>

you can define it in TypeSpec as follows:

model MyCustomAuth {
  type: Http.AuthType.http;
  scheme: "SharedKey";
}

ApiKeyAuth<TLocation extends ApiKeyLocation, TName extends string>

An API key is a token that a client provides when making API calls. The key can be sent in different locations:

In the query string:

GET /something?api_key=abcdef12345
@useAuth(ApiKeyAuth<ApiKeyLocation.query, "api_key">)

Or as a request header:

GET /something HTTP/1.1
X-API-Key: abcdef12345
@useAuth(ApiKeyAuth<ApiKeyLocation.header, "X-API-KEY">)

Or as a cookie:

GET /something HTTP/1.1
Cookie: X-API-KEY=abcdef12345
@useAuth(ApiKeyAuth<ApiKeyLocation.cookie, "X-API-KEY">)

OAuth2Auth<TFlows extends OAuth2Flow[]>

OAuth 2.0 is an authorization protocol that gives an API client limited access to user data on a web server. OAuth relies on authentication scenarios called flows, which allow the resource owner (user) to share protected content from the resource server without sharing their credentials. For this purpose, an OAuth 2.0 server issues access tokens that client applications can use to access protected resources on behalf of the resource owner. For more information about OAuth 2.0, see oauth.net and RFC 6749.

Application hierarchy

The @useAuth decorator can be used on a service namespace, sub-namespace, interface or operation. The security scheme specified will be applied to all operations contained in the type. A child type with a @useAuth will override the security scheme of the parent type. If you want to add a new scheme rather than override, you must re-specify all the parent’s security schemes along with the new one.

Examples

All operations of MyService will use BasicAuth to authenticate:

@useAuth(BasicAuth)
namespace MyService;


op one(): void;
op two(): void;

In this example, one will use ApiKey auth and two will use Basic auth:

@useAuth(BasicAuth)
namespace MyService;


@useAuth(ApiKeyAuth<ApiKeyLocation.query, "api_key">)
op one(): void; // Use ApiKey only
op two(): void; // Use BasicAuth

Here, one will accept either ApiKey or Basic auth, while two will only accept Basic auth:

@useAuth(BasicAuth)
namespace MyService;


@useAuth(BasicAuth | ApiKeyAuth<ApiKeyLocation.query, "api_key">)
op one(): void; // Use either BasicAuth OR ApiKey
op two(): void; // Use BasicAuth only

OAuth2 Scopes

The OAuth2 security scheme can require specific scopes that must be granted to the OAuth2 token to access the operations the security scheme applies to. When different operations need different scopes, you will likely want to create a template that allows providing OAuth scopes without having to respecify the other properties of the security scheme:

@useAuth(MyOAuth2<["read"]>)
namespace DemoService;


alias MyOAuth2<Scopes extends string[]> = OAuth2Auth<
  [
    {
      type: OAuth2FlowType.implicit;
      authorizationUrl: "https://api.example.com/oauth2/authorize";
      refreshUrl: "https://api.example.com/oauth2/refresh";
    }
  ],
  Scopes
>;


// Use OAuth2 with the "read" scope
op list(): string[];


// Use OAuth2 with the "read" scope or no authentication at all
@useAuth(MyOAuth2<["read"]> | NoAuth)
op read(): string;


// Use OAuth2 with the "write" scope
@useAuth(MyOAuth2<["write"]>)
op write(value: string): void;


// Use OAuth2 with the "delete" scope
@useAuth(MyOAuth2<["delete"]>)
op delete(value: string): void;