Multi-Tenancy Support

1. Introduction to Multi-Tenancy

Multi-tenancy is a software architecture pattern that allows multiple tenants to share a single system instance while ensuring data isolation between tenants. This enables resource reuse, unified upgrades and maintenance, standardized data analysis, and large-scale promotion.

OpenMeta natively supports two multi-tenancy modes: shared application with shared database mode, and shared application with independent database mode. Once multi-tenancy is enabled, data is automatically isolated by tenant.

2. Enabling Multi-Tenancy

2.1 Multi-Tenancy Mode 1: Shared Application with Shared Database

Enable multi-tenancy by setting system.multi-tenancy.enable=true in the configuration file. For example:

system:
  multi-tenancy:
    enable: true

2.2 Multi-Tenancy Mode 2: Shared Application with Independent Database

Since OpenMeta supports dynamic multi-data sources, the UserInfo object includes tenantId and datasourceKey fields.

When a user logs in, these fields can be populated in the ContextInterceptor interceptor implementation.

Enable multi-tenancy in the configuration file by setting system.multi-tenancy.enable=true, and also enable dynamic multi-data source with the mode set to multi-tenancy-isolated.

system:
  multi-tenancy:
    enable: true
spring:
  datasource:
    dynamic:
      enable: true
      # mode: read-write-separation, switch-by-model, multi-tenancy-isolated, multi-datasource(default)
      mode: multi-tenancy-isolated
      datasource:
        tenant1:
          driver-class-name: com.mysql.cj.jdbc.Driver
          url: jdbc:mysql://localhost:3306/demo
          username: user0
          password: pass0
        tenant2:
          driver-class-name: com.mysql.cj.jdbc.Driver
          url: jdbc:mysql://localhost:3306/db1
          username: user1
          password: pass1
        tenant3:
          driver-class-name: com.mysql.cj.jdbc.Driver
          url: jdbc:mysql://localhost:3306/db2
          username: user2
          password: pass2

3. Multi-Tenancy Data Model

Once multi-tenancy is enabled, data isolation can be configured at the model level.

Conditions for Enabling Tenant Isolation in Models:

• Set the model metadata multiTenant = true. This multiTenant attribute controls which data models are subject to tenant isolation. Models with multiTenant = false can be shared across tenants.
• Add a tenantId field to the model. This field is globally read-only and is populated with the tenantId of the current user upon creation. Modifying this field is not allowed.

4. Data Isolation Strategies Between Tenants

Once multi-tenancy is enabled, the ORM enforces strict isolation and validation. The current user’s tenantId is recorded in the context (user.tenantId).

4.1 Simple Queries

The ORM automatically appends a tenant filter condition to the WHERE clause:

tenant_id = user.tenantId

4.2 JOIN Queries

The tenant filter condition is automatically appended to both the main table and the related tables without requiring developer intervention:

t0.tenant_id = user.tenantId AND t1.tenant_id = user.tenantId

4.3 Data Creation

During data creation, the ORM automatically populates the tenantId field:

tenantId = user.tenantId

If the client specifies a tenantId that differs from the current user’s tenantId, the system will throw an exception, indicating a potential unauthorized access attempt.

4.4 Data Updates

Since the tenantId field in the data model is read-only, the ORM ignores any attempts to modify the tenantId.

4.5 Data Deletion

Before deletion, the ORM checks the data scope, ensuring that only data belonging to the current user’s tenant can be deleted.

5. Multi-Tenant System Operations Platform

Operating a multi-tenant system requires cross-tenant data access for tenant management, data configuration, and analysis.

5.1 Operations Platform Without Tenant Isolation

The operations platform should deploy separate front-end and back-end services with a unique access domain. In this system, multi-tenancy should not be enabled, i.e., system.multi-tenancy.enable = false.

5.2 Tenant Properties in the Operations Platform

In the operations platform, tenants are treated as an attribute of data authorization. The tenantId field in data models serves only as a cross-tenant data authorization condition. Even if the data model includes a tenantId field, it is not subject to multi-tenancy restrictions enforced by the ORM layer.