@travetto/auth

Authentication

Authentication scaffolding for the Travetto framework

Install: @travetto/auth

npm install @travetto/auth

# or

yarn add @travetto/auth

This module provides the high-level backdrop for managing security principals. The goal of this module is to be a centralized location for various security frameworks to plug into. The primary contributions are:

• Standard Types
• Authentication Contract
• Authorization Contract
• Authorization Services
• Authorization Context

Standard Types

The module's goal is to be as flexible as possible. To that end, the primary contract that this module defines, is that of the Principal.

Code: Principal

export interface Principal<D = AnyMap> {
  /**
   * Primary identifier for a user
   */
  readonly id: string;
  /**
   * Unique identifier for the principal's lifecycle
   */
  readonly sessionId?: string;
  /**
   * Date of expiration
   */
  expiresAt?: Date;
  /**
   * Date of issuance
   */
  issuedAt?: Date;
  /**
   * The source of the issuance
   */
  readonly issuer?: string;
  /**
   * Supplemental details
   */
  readonly details: D;
  /**
   * List of all provided permissions
   */
  readonly permissions?: string[];
}

As referenced above, a Principal is defined as a user with respect to a security context. This can be information the application knows about the user (authorized) or what a separate service may know about a user (3rd-party authentication).

Authentication Contract

Code: Authenticator

export interface Authenticator<T = unknown, C = unknown, P extends Principal = Principal> {
  /**
   * Retrieve the authenticator state for the given request
   */
  getState?(context?: C): Promise<AuthenticatorState | undefined> | AuthenticatorState | undefined;

  /**
   * Verify the payload, ensuring the payload is correctly identified.
   *
   * @returns Valid principal if authenticated
   * @returns undefined if authentication is valid, but incomplete (multi-step)
   * @throws AppError if authentication fails
   */
  authenticate(payload: T, context?: C): Promise<P | undefined> | P | undefined;
}

The Authenticator only requires one method to be defined, and that is authenticate. This method receives a generic payload, and a supplemental context as an input. The interface is responsible for converting that to an authenticated principal.

Authorization Contract

Code: Authorizer

export interface Authorizer<P extends Principal = Principal> {
  /**
   * Authorize inbound principal, verifying it's permission to access the system.
   * @returns New principal that conforms to the required principal shape
   */
  authorize(principal: P): Promise<P> | P;
}

Authorizers are generally seen as a secondary step post-authentication. Authentication acts as a very basic form of authorization, assuming the principal store is owned by the application.

The Authorizer only requires one method to be defined, and that is authorize. This method receives an authenticated principal as an input, and is responsible for converting that to an authorized principal.

Example

The Data Modeling Support extension is a good example of an authenticator. This is a common use case for simple internal auth.

Overall, the structure is simple, but drives home the primary use cases of the framework. The goals are:

• Be able to identify a user uniquely
• To have a reference to a user's set of permissions
• To have access to the principal

Authorization Services

Code: Authorization Service

export class AuthService {
  @Inject()
  /**
   * Get authenticators by keys
   */
  async getAuthenticators<T = unknown, C = unknown>(keys: symbol[]): Promise<Authenticator<T, C>[]>;
  /**
   * Authenticate. Supports multi-step login.
   * @param ctx The authenticator context
   * @param authenticators List of valid authentication sources
   */
  async authenticate<T, C>(payload: T, context: C, authenticators: symbol[]): Promise<Principal | undefined>;
  /**
   * Manage expiry state, renewing if allowed
   */
  manageExpiry(p?: Principal): void;
  /**
   * Enforce expiry, invalidating the principal if expired
   */
  enforceExpiry(p?: Principal): Principal | undefined;
}

The AuthService operates as the owner of the current auth state for a given "request". "Request" here implies a set of operations over a period of time, with the http request/response model being an easy point of reference. This could also tie to a CLI operation, or any other invocation that requires some concept of authentication and authorization.

The service allows for storing and retrieving the active Principal, and/or the actively persisted auth token. This is extremely useful for other parts of the framework that may request authenticated information (if available). Web Auth makes heavy use of this state for enforcing endpoints when authentication is required.

Login

"Logging in" can be thought of going through the action of finding a single source that can authenticate the identity for the request credentials. Some times there may be more than one valid source of authentication that you want to leverage, and the first one to authenticate wins. The AuthService operates in this fashion, in which a set of credentials and potential Authenticators are submitted, and the service will attempt to authenticate.

Upon successful authentication, an optional Authorizer may be invoked to authorize the authenticated user. The Authenticator is assumed to be only one within the system, and should be tied to the specific product you are building for. The Authorizer should be assumed to have multiple sources, and are generally specific to external third parties. All of these values are collected via the Dependency Injection module and will be auto-registered on startup.

If this process is too cumbersome or restrictive, manually authenticating and authorizing is still more than permissible, and setting the principal within the service is a logical equivalent to login.

Authorization Context

When working with framework's authentication, the authenticated information is exposed via the AuthContext, object.

Code: Auth Context Outline

export class AuthContext {
  @Inject()
  /**
   * Set principal
   */
  set principal(p: Principal | undefined);
  /**
   * Get the authentication token, if it exists
   */
  get authToken(): AuthToken | undefined;
  /**
   * Set/overwrite the user's authentication token
   */
  set authToken(token: AuthToken | undefined);
  /**
   * Get the authenticator state, if it exists
   */
  get authenticatorState(): AuthenticatorState | undefined;
  /**
   * Set/overwrite the authenticator state
   */
  set authenticatorState(state: AuthenticatorState | undefined);
  /**
   * Clear context
   */
  async clear(): Promise<void>;
}