Last week we looked at how we can create a Monorepo and setup Microservices that are connected simply via TCP. This post will build upon that post!
So if you missed it click here
Installing Redis
What is Redis:
Redis is an open-source (BSD licensed), in-memory data structure store, used as a database, cache and message broker. It supports data structures such as strings, hashes, lists, sets, sorted sets with range queries, bitmaps, hyperloglogs, geospatial indexes with radius queries and streams.
That's a mouthful. Let's break it down a little bit.
'in-memory' Means that Redis is running and storing everything in RAM. So it can run ultra-fast. 'data structure store' You can replace this with a database. A message broker can receive a message in one format and send it in the appropriate format to a receiver. Imagin 3 people speaking only german one speaking only English and the third person speaks German and English. This third person is like a message broker. He/She translates from English to German and the other way around.
Redis has a lot more functions than just this but we will use it as a message broker.
I'm using WSL(2) for development and installing the Redis server is easy on Ubuntu/Debian. You just need to run:
sudo apt install redis-server
That's it! And Redis Server should also be available on your OS!
Now we need to start Redis.
#On WSL
sudo service redis-server start
#On Ubuntu
sudo systemctl redis-server start
Let us store 'Hello dev.to!' in our Redis database.
For that we can enter the redis-cli
. Type:
redis-cli
Now you should see something like:
127.0.0.1:6379>
we can now type:
set test "Hello dev.to!"
We Should get an OK
back from Redis
To retrieve the value we just need to type:
get test
You now should see Hello dev.to!
. Good, our Redis server is working! Let's exit it with
exit
Sending messages with Redis in NestJS
First, we need to add the redis
package to our project with:
yarn add redis
Now that we have Redis installed we just need to change 2 files! Yes in our case only 2! amazing right? So let's do it!
First apps/blog/src/main.ts
import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import { Transport } from '@nestjs/microservices';
import { Logger } from '@nestjs/common';
const logger = new Logger('Blog');
async function bootstrap() {
const app = await NestFactory.createMicroservice(AppModule, {
transport: Transport.REDIS,
options: {
url: 'redis://localhost:6379',
},
});
await app.listen(() => logger.log('Microservice is listening'));
}
bootstrap();
We just changed the transport option from TCP
to REDIS
and of course, now we need to change the server.
Second apps/lampeweb/src/app.service.ts
import { Injectable } from '@nestjs/common';
import {
ClientProxyFactory,
Transport,
ClientProxy,
} from '@nestjs/microservices';
@Injectable()
export class AppService {
private client: ClientProxy;
constructor() {
this.client = ClientProxyFactory.create({
transport: Transport.REDIS,
options: {
url: 'redis://localhost:6379',
}
});
}
public getHello(): Promise<string> {
return this.client.send<string, string>('getHello', 'Michael').toPromise();
}
}
Here again, we are just chaining the ClientProxyFactory.create
function to the same values as before. In a bigger project, this should not be hardcoded but rather passed in via env
.
We now just need to run our services again and we should see the same message as last time!
I hope you liked that post! If you want a follow-up, please comment, like, and share. So I can know that you are interested in content like that!
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Top comments (1)
After I change transport in blog to redis, I cannot start service