Authentication Service (PART II)

Christopher Woodward Christopher Woodward
Authentication Service

"The film vault" by Sean_Marshall is licensed under CC BY-NC 2.0

Introduction

In the previous article ( Authentication Service Part I), we discussed how we would build the Authentication Service. In this article, we will implement the primary components of the service.

Requirements

Before you get started, you will need the following:
  • Java
  • Maven
  • Docker
  • Docker-Compose
Refer to the Development Toolbox article if you do not have these installed locally.

Building the Authentication Service

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Additional Infrastructure

As we develop the AuthenticationService, we will need three additional infrastructure elements. A PostgreSQL relational database instance, a PGAdmin-4 PostgreSQL Admin UI, and a RabbitMQ message broker instance. We will deploy both as Docker container images from their respective official Docker Hub repositories. We will add the following to our new Docker-Compose file: 

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Data Model

The Authentication Service has a simple data model consisting of three tables:
  • users-Contains user authentication credentials and token related fields.
  • roles-Contains a label value pair representing a particular privilege classification.
  • users_roles-Provides the many-to-many relationship between Users and Roles.S

Repositories


The AccountService contains two repositories corresponding to the two entities User and Role.

User Repository

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The User Repository interface extends Spring's CrudRepository class to provide basic persistence methods. These methds are supplemented by service-specfic methods.

Role Repository

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Repository Data Model

User 

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Role 

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The Role Repository interface extends Spring's CrudRepository class to provide basic persistence methods. These methods are supplemented by service-specfic methods.

Account Event Publisher

The Authentication Service acts as an event-source within the larger application. As service methods are invoked, they publish events to the application's message bus. These include:

  • Registered
  • Authenticated
  • Authentication Failed
  • Password Changed
  • Password Recovery Requested
  • Password Recovered
  • Account Status Changed
These events can be consumed by other services in the application. The AuthenticationService leverages the Spring Cloud Stream framework to handle message broker connection and event publishing. This minimimizes the amount of code we must implement to two classes:

  • AccountEventSource- this interface names our outqoing message channel (accountEventChannel) as well as providing a named method to access the message channel (accountEvents()). 

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  • AccountEventPublisher- this class binds the publisher to the previously defined AccountEventSource. 

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By defining the interface, class, and corresponding application.yml configuration properties, the Spring Cloud Stream framework has enough information to connect to the message broker and publish messages to the configured queue. When we wish to publish an event we simply call: 

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In addition to sending the message event as the message payload, we also set the message header type to ACCOUNT_REGISTERED_EVENT. We use the type header in message listeners to route the appropriate messages to the desired handler methods

JWT Provider

One of the primary responsibilities of the AuthenticationService is the generation of JSON Web tokens. To accomplish this we create the JWTProvider class. This class is responsible for generating a JWT from a User entity and a list of Granted Authorities, as well as providing utility methods to read read : 

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Email Client Component

An EmailClient component provides integration with the NotificationService Email REST endpoint. This component creates and instance of EmailMessage using it's builder and calls the RestTemplate's postForEntity method to call the endpoint method. 

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Resources



Coming Up

In the third article in the series, we will continue the AuthenticationService implementation by discussing selected AuthenticationService class methods, the JWTAuthorizationFilter, and the AuthenticationController REST endpoint.