README.md

Connection Pool per Module

This sample demonstrates how to isolate connection pools per module using a custom AbstractRoutingDataSource. This allows choosing a data source per module at runtime.

Implementation

The implementation uses Spring's @RestController stereotype along with an interceptor to route to the appropriate data source based on the package the request comes from:

Package	Pool
helpscout.notification	notification_pool
helpscout.user	user_pool
else	default_pool

Data Source Settings

The data source settings are defined in application.yml and are loaded into a custom ModuleDataSourceProperties bean to allow having a structure like:

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/helpscout
    password: test
    username: test
    hikari:
      connection-timeout: 20000
      max-lifetime: 300000
    instances:
      - name: default_pool
        pool-size: 10
      - name: notification_pool
        pool-size: 10
      - name: user_pool
        pool-size: 10

Quick Start

1. Start the MySQL database and Flyway scripts using Docker Compose:

   docker compose up

2. Build and start the project:

   ./gradlew clean build
   ./gradlew bootRun

Endpoints

This demo provides the following endpoints:

• GET http://localhost:8080/v1/notifications
• GET http://localhost:8080/v1/notifications/{id}
• GET http://localhost:8080/v1/users
• GET http://localhost:8080/v1/users/{id}

Depending on the endpoint you hit, you may see the following message in the console:

Routing datasource to {current}_pool

Integration Tests

A few integration tests are available to validate that the routing works correctly.