Muti-tenant NestJS

This is a starter kit for creating multi-tenant NestJS APIs using Prisma and PostgreSQL.

How to run locally

1. Create `./.env` file

MAIN_DATABASE_URL="postgresql://johndoe:randompassword@localhost:5432/mydb?schema=public"
TENANT_DATABASE_URL="postgresql://johndoe:randompassword@localhost:5432/mydb?schema=public"

Update the database URLs as required. If the database instances do not contain the right schema, you can create that using prisma db push once the dependencies are ready.

2. Install dependencies

pnpm install

Once the installation completes, postinstall should generate the PrismaClients.

3. Run `dev` or `start`

pnpm dev

pnpm start

How to update database schema

There are two .prisma files inside ./prisma/.

schema.prisma for the Main Database
tenant-schema.prisma for the Tenant Database

Do the necessary changes in the appropriate file and run the correct script.

Schema changes on the Main Database

pnpm prisma:main:push

Schema changes on the Tenant Database

pnpm prisma:tenant:push

How to use the PrismaClient inside NestJS Application

MainPrismaService

import { MainPrismaService } from '@/modules/prisma/main-prisma.service';

export class NestJSComponent {
  constructor(
    private readonly mainPrisma: MainPrismaService,
  ) {}
}

> Example:

@Get('/tenants')
async getTenants() {
  const tenants = await this.mainPrisma.tenant.findMany();

  return { tenants };
}

TenantPrismaService

import { TENANT_PRISMA_SERVICE, TenantPrismaService } from '@/modules/prisma/tenant-prisma.service';

export class NestJSComponent {
  constructor(
    @Inject(TENANT_PRISMA_SERVICE) private readonly tenantPrisma: TenantPrismaService
  ) {}
}

> Example:

@Get('/users')
async getUsers() {
  /**
   * Since we're using query extensions with the Prisma client,
   * this query should return only the users with the column
   * "tenantId" matching that in the request "x-tenant-code".
   */
  const users = await this.tenantPrisma.user.findMany();

  return { users };
}

Diagrams

Request-Response Life Cycle

flowchart TB
  Client((Client))
  API((API))
  MainDB[(MainDB)]
  Guards[[AuthGuard<br>UserGuard<br>RolesGuard]]

  Client --Request--> API --> RequestLoggerMiddleware --> TenantDatasourceMiddleware --> Guards --> Controller --> API --Response--> Client
  TenantDatasourceMiddleware---MainDB

Entity Relationship

erDiagram
    Main--Tenant {
        int id PK
        string code
        string name
        string website
        json metadata
        int datasourceId FK
    }
    Main--Datasource {
        int id PK
        string name
        string url
        json metadata
    }
    TenantDBX--Entity {
        int id PK
        any key
        int tenantId FK
    }
    Main--Tenant ||--o| Main--Datasource : has
    Main--Tenant ||--o{ TenantDBX--Entity : has

Data

Datasources

Datasource	Main DB	Tenant DB 1	Tenant DB 2	Tenant DB 3
Tenant(s)	Metadata	A B C	D E F	G H I

Data flow

flowchart LR
  API((API Main))
  APITSM[[TenantDatasourceMiddleware]]
  APIController[[Controller]]
  MainDb[(Main DB)]
  TenantDb1[(Tenant DB 1)]
  TenantDb2[(Tenant DB 2)]
  TenantDb3[(Tenant DB 3)]
  ClientA[Client A]
  ClientB[Client B]
  ClientC[Client C]
  ClientD[Client D]
  ClientE[Client E]
  ClientF[Client F]
  ClientG[Client G]
  ClientH[Client I]

  API <--(1)--> APITSM <--Get datasourceUrl--> MainDb
  API --(2)--> APIController
  ClientA --Data A--> API
  ClientB --Data B--> API
  ClientC --Data C--> API
  ClientD --Data D--> API
  ClientE --Data E--> API
  ClientF --Data F--> API
  ClientG --Data G--> API
  ClientH --Data H--> API
  ClientI --Data I--> API
  APIController -.Data A.->TenantDb1
  APIController -.Data B.->TenantDb1
  APIController -.Data C.->TenantDb1
  APIController -.Data D.->TenantDb2
  APIController -.Data E.->TenantDb2
  APIController -.Data F.->TenantDb2
  APIController -.Data G.->TenantDb3
  APIController -.Data H.->TenantDb3
  APIController -.Data I.->TenantDb3

filipemacedo/multi-tenant-nestjs