Demo for Multitenancy with Spring Boot and JPA

Description

Demonstrate a technical implementation of database routing with Spring boot JPA utilizing AbstractRoutingDataSource for database routing at runtime.

• Based on Providing Multitenancy with Spring Boot
• Extended with dockerized MySql 8 Server, managing containers with docker-compose and different spring profiles

Note about MySQL's 'schema vs database' notion

From MySQL 8.0 Reference Manual: schema is synonymous with database.

Prep for Demo

From your command line run docker-compose:

• Start containers rebuilding it (--build flag) in the background (-d option): docker-compose up --build -d
• Check the containers: docker ps -a
• You can connect to the MySql8 Server from your favourite DB-tool:
  • url: localhost:3306
  • credentials: -u=dbuser -p=password
• Or use the Adminer: http://localhost:8181/?server=mysql-docker&username=dbuser
  • Adminer (formerly phpMinAdmin) is a simple and lightweight php web application to work with your databases like mysql
• Open your browser and go to http://localhost:8080/entity/all
  • mydb1 is the default schema
• Better use Postman Collection
  • Switch between databases (schemas) by setting the X-TenantID http-header accordingly (mydb1 or mydb2)

Demo Issue with startup order and dependencies

• Change the profile in the Dockerfile to local
• Rebuild everything:
  • docker-compose down -v
  • docker-compose up --build
• Look at the logs for "ERROR com.zaxxer.hikari.pool.HikariPool : HikariPool-1 - Exception during pool initialization. ... com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure"

Build and Run the Spring-Boot service locally with Maven

Build

• mvn clean verify

Run

Precondition: MySql8 Server is started (docker-compose up -d)

Use the dev profile which starts the Spring-Boot-App at port 8282 (to avoid conflict with the container started by docker-compose):

• mvn spring-boot:run -Dspring-boot.run.profiles=dev
• Go to http://localhost:8282/entity/all
• Use the Postman Collection

Commands

Start all Docker Container (to rebuild use '--build' flag):

• docker-compose up to create and start containers
• docker-compose up -d to start in the background/as deamon
• docker-compose up --build -d to rebuild and start as deamon

Check running Container:

• docker ps -a

Stop Docker Containter

NOTE: Init the DB using the Script. The docker-entrypoint-initdb.d folder will only be run once while the container is created (instantiated) so you actually have to do a docker-compose down -v to re-activate this for the next run.

• docker-compose stop to stop all containers
• docker-compose down to stop and remove all containers
• docker-compose down -v to remove also volumes