This application demonstrates multi-tenancy in a Spring-Boot 2 app using a discriminator field with Hibernate.

Run the app:

$ createdb spring-multi-tenancy
$ ./mvnw clean spring-boot:run

From another terminal:

$ curl localhost:8080/employees -H "X-TenantID: tenant1" 
[{"userId":"16b5308b-6bb8-4a75-ae93-66dc71a0b981","firstName":"John","lastName":"Doe","tenantId":"tenant1"}]

$ curl localhost:8080/employees -H "X-TenantID: tenant3" 
[]

$ curl localhost:8080/employees -H "X-TenantID: tenant3" -H "Content-Type: application/json" -X POST -d '{"firstName":"joe"}'
{"userId":"c77ad6bb-b2ad-47f7-b21c-3e50deb6a574","firstName":"joe","lastName":null,"tenantId":"tenant3"}

$ curl localhost:8080/employees -H "X-TenantID: tenant3" 
[{"userId":"c77ad6bb-b2ad-47f7-b21c-3e50deb6a574","firstName":"joe","lastName":null,"tenantId":"joe"}]

• Uses hibernate filter to limit the query results based on tenant.
• Uses hibernate interceptors to enforce tenant details during creating/updating entities.
• Uses Spring AOP (AspectJ) to set the filter parameters.
• Each request goes thru a custom servlet filter which checks for X-TenantID http header and set's it in the ThreadLocal variable using TenantContext class. If http header is not present in request, it'll be rejected.
• Controller routes the request to Service class and the Spring AOP (EmployeeServiceAspect class) intercepts the service call and set's the hibernate tenant filter.
• All the service method has to be annotated with @Transactional for EmployeeServiceAspect to work.
• Above method works only for read queries, for write queries, we have to use hibernate interceptors.
• Custom Entity interceptor (using EmptyInterceptor) class which sets the tenantId value during the save/delete/flush-dirty entity events.
• Entity class should implement TenantSupport interface for the Entity interceptor to work.

• https://hibernate.atlassian.net/browse/HHH-6054
• https://docs.jboss.org/hibernate/orm/5.2/userguide/html_single/Hibernate_User_Guide.html#multitenacy
• https://docs.jboss.org/hibernate/orm/5.2/userguide/html_single/Hibernate_User_Guide.html#mapping-column-filter
• https://docs.jboss.org/hibernate/orm/5.2/userguide/html_single/Hibernate_User_Guide.html#events

• https://github.com/ramsrib/multi-tenant-app-demo
• https://github.com/spring-labs/tenancy-sample

MIT