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Multi database Setup
In part 1, we set up the nestjs framework and configured and tested microservices architecture application using nest.js. In part 2, we used Sequelize and mongoose to access the database and tested for both MySQL database and MongoDB.
In this part; we will see how to let the application connect to multiple databases depending on the request. Since it is a multi-tenancy application, each tenant has their own database containing their data accessing the same application, thus the application needs to connect to different databases.
We will change the pass repository option method and use forRootAsync()
instead of forRoot()
, we need to use a custom class for configuration.
For both sequelize and mongoose, add this:
MongooseModule.forRootAsync({
useClass:MongooseConfigService
}),
SequelizeModule.forRootAsync({
useClass:SequelizeConfigService
})
We will create a config file and two classes: MongooseConfigService
and SequelizeConfigService
The plan here is to add injection for each incoming request and use a domain to switch between connections.
So we need to use
@Injectable({scope:Scope.REQUEST})
, and on the class constructor we use@Inject(REQUEST) private read-only request
so we can get host information from request data.For example let say the domain is example.com, and we have a tenant called
company1
, then the domain will be company1.example.com. Same thing forcompany2
tenant, the domain will be company2.example.com and so on.
config/MongooseConfigService.ts
import { Inject, Injectable, Scope } from "@nestjs/common";
import { REQUEST } from "@nestjs/core";
import { MongooseModuleOptions, MongooseOptionsFactory } from "@nestjs/mongoose";
@Injectable({scope:Scope.REQUEST})
export class MongooseConfigService implements MongooseOptionsFactory {
constructor(@Inject(REQUEST) private readonly request,){}
createMongooseOptions(): MongooseModuleOptions {
let domain:string[]
let database='database_development'
if(this.request.data ){
domain=this.request.data['host'].split('.')
console.log(this.request)
}
else{
domain=this.request['headers']['host'].split('.')
}
console.log(domain)
if(domain[0]!='127' && domain[0]!='www' && domain.length >2){
database='tenant_'+domain[0]
console.log('current DB',database)
}
return {
uri: 'mongodb://localhost:27017/'+database,
};
}
}
config/SequelizeConfigService.ts
import { Inject, Injectable, Scope } from "@nestjs/common";
import { REQUEST } from "@nestjs/core";
import { CONTEXT, RedisContext, RequestContext } from "@nestjs/microservices";
import { SequelizeModuleOptions, SequelizeOptionsFactory} from "@nestjs/sequelize";
@Injectable({scope:Scope.REQUEST})
export class SequelizeConfigService implements SequelizeOptionsFactory {
constructor(@Inject(REQUEST) private readonly request:RequestContext){}
createSequelizeOptions(): SequelizeModuleOptions {
let domain:string[]
let database='database_development'
if(this.request.data ){
domain=this.request.data['host'].split('.')
console.log(this.request)
}
else{
domain=this.request['headers']['host'].split('.')
}
console.log(domain)
if(domain[0]!='127' && domain[0]!='www' && domain.length >2){
database='tenant_'+domain[0]
console.log('current DB',database)
}
return {
dialect: 'mysql',
host: 'localhost',
port: 3306,
username: 'ismaeil',
password: 'root',
database: database,
autoLoadModels: true,
synchronize: true,
};
}
}
After finishing the configuration, we need to do some work to test it because we need to map our localhost and IP to a domain. I will try to use two ways to test the application locally but for the production, it will be a configuration in your domain provider.
Go to the following file in Linux: /etc/hosts
and in windows: c:\windows\system32\drivers\etc\hosts
and add
## lines
127.0.0.1 example.com
127.0.0.1 company1.example.com
127.0.0.1 company2.example.com
In linux you can install dnsmasq and follow these steps
1- Install dnsmasq in NetworkManager.
2- Add the configuration file
sudo nano /etc/NetworkManager/dnsmasq.d/dnsmasq-localhost.conf
.add this line in the file:
address=/.example.com/127.0.0.1
3- Restart the service
sudo systemctl reload NetworkManager
.
Source code available in git branch multi-database
Next in part 4 we will add a security level and user roles.