spring-modular-monolith

An e-commerce application following Modular Monolith architecture using Spring Modulith. The goal of this application is to demonstrate various features of Spring Modulith with a practical application.

This application follows modular monolith architecture with the following modules:

• Common: This module contains the code that is shared by all modules.
• Catalog: This module manages the catalog of products and stores data in catalog schema.
• Orders: This module implements the order management and stores the data in orders schema.
• Inventory: This module implements the inventory management and stores the data in inventory schema.
• Notifications: This module handles the events published by other modules and sends notifications to the interested parties.

Goals:

• Implement each module as independently as possible.
• Prefer event-driven communication to direct module dependency wherever applicable.
• Store data managed by each module in an isolated manner by using different schema or database.
• Each module should be testable by loading only module-specific components.

Module communication:

• Common module is an OPEN module that can be used by other modules.
• Orders module invokes the Catalog module public API to validate the order details
• When an Order is successfully created, the Orders module publishes "OrderCreatedEvent"
• The "OrderCreatedEvent" will also be published to external broker like RabbitMQ. Other applications may consume and process those events.
• Inventory module consumes "OrderCreatedEvent" and updates the stock level for the products.
• Notifications module consumes "OrderCreatedEvent" and sends an order confirmation email to the customer.

Prerequisites

• JDK 25
• Docker and Docker Compose
• Your favourite IDE (Recommended: IntelliJ IDEA)

Follow the Installation Guide to install the required tools.

Verify the prerequisites:

$ java -version
$ docker info
$ docker compose version
$ task --version

Using task to perform various tasks:

$ task test // runs all tests

$ task format // formats java code using spotless

$ task build_image // builds docker image

$ task start // starts app using docker compose
$ task stop
$ task restart

• Application URL: http://localhost:8080
• Actuator URL: http://localhost:8080/actuator
• Actuator URL for modulith: http://localhost:8080/actuator/modulith
• RabbitMQ Admin URL: http://localhost:15672 (Credentials: guest/guest)
• Grafana URL: http://localhost:3000

Deploying on k8s cluster

Set up a Kind cluster following Installation Guide

# deploy app to kind cluster 
$ task k8s_deploy

# undeploy app
$ task k8s_undeploy

• Application URL: http://localhost:30090
• RabbitMQ Admin URL: http://localhost:30091 (Credentials: guest/guest)
• Grafana URL: http://localhost:30092