ztobs / financial-advisor Goto Github PK

A simple financial advisor app built using microservice architecture, Spring Boot, Spring Cloud and Docker.

Decomposed into three core microservices. All of them are independently deployable applications organized around certain business domains.

Contains general input logic and validation: incomes/expenses items, savings and account settings.

Performs calculations on major statistics parameters and captures time series for each account. Datapoint contains values normalized to base currency and time period. This data is used to track cash flow dynamics during the account lifetime.

Stores user contact information and notification settings (reminders, backup frequency etc). Scheduled worker collects required information from other services and sends e-mail messages to subscribed customers.

• Each microservice has its own database, so there is no way to bypass API and access persistence data directly.
• MongoDB is used as a primary database for each of the services.
• All services are talking to each other via the Rest API

Spring cloud provides powerful tools for developers to quickly implement common distributed systems patterns -

Spring Cloud Config is horizontally scalable centralized configuration service for the distributed systems. It uses a pluggable repository layer that currently supports local storage, Git, and Subversion.

In this project, we are going to use native profile, which simply loads config files from the local classpath. You can see shared directory in Config service resources. Now, when Notification-service requests its configuration, Config service responses with shared/notification-service.yml and shared/application.yml (which is shared between all client applications).

Just build Spring Boot application with spring-cloud-starter-config dependency, autoconfiguration will do the rest.

Now you don't need any embedded properties in your application. Just provide bootstrap.yml with application name and Config service url:

spring:
  application:
    name: notification-service
  cloud:
    config:
      uri: http://config:8888
      fail-fast: true

For example, EmailService bean is annotated with @RefreshScope. That means you can change e-mail text and subject without rebuild and restart the Notification service.

First, change required properties in Config server. Then make a refresh call to the Notification service: curl -H "Authorization: Bearer #token#" -XPOST http://127.0.0.1:8000/notifications/refresh

You could also use Repository webhooks to automate this process

• @RefreshScope doesn't work with @Configuration classes and doesn't ignores @Scheduled methods
• fail-fast property means that Spring Boot application will fail startup immediately, if it cannot connect to the Config Service.

Authorization responsibilities are extracted to a separate server, which grants OAuth2 tokens for the backend resource services. Auth Server is used for user authorization as well as for secure machine-to-machine communication inside the perimeter.

In this project, I use Password credentials grant type for users authorization (since it's used only by the UI) and Client Credentials grant for service-to-service communciation.

Spring Cloud Security provides convenient annotations and autoconfiguration to make this really easy to implement on both server and client side. You can learn more about that in documentation.

On the client side, everything works exactly the same as with traditional session-based authorization. You can retrieve Principal object from the request, check user roles using the expression-based access control and @PreAuthorize annotation.

Each PiggyMetrics client has a scope: server for backend services and ui - for the browser. We can use @PreAuthorize annotation to protect controllers from an external access:

@PreAuthorize("#oauth2.hasScope('server')")
@RequestMapping(value = "accounts/{name}", method = RequestMethod.GET)
public List<DataPoint> getStatisticsByAccountName(@PathVariable String name) {
	return statisticsService.findByAccountName(name);
}