TypeScript is a powerful language that provides static type-checking along with features like classes, interfaces, and modules, to JavaScript development. Nest.js is a Node.js framework for building efficient, scalable, and enterprise-grade server-side applications.
In this article, we'll explore how to develop a microservice using TypeScript and Nest.js. We'll start by looking at the benefits of using TypeScript and Nest.js for microservices. We'll then create a simple microservice using TypeScript and Nest.js. Finally, we'll deploy our microservice to a server.
There are many benefits to using TypeScript and Nest.js for developing microservices. TypeScript provides static type-checking, which can help catch errors early in the development process. TypeScript's ability to import other TypeScript files means that you can easily modularize your code. Nest.js is built on top of TypeScript and shares many of its benefits. In addition, Nest.js provides a powerful module system that can help you organize your code.
Nest.js also provides a number of features that are helpful for developing microservices. Nest.js is designed to be scalable and easy to use. It also supports a number of features that are helpful for microservices, such as message queues and databases.
Now that we've looked at the benefits of using TypeScript and Nest.js for developing microservices, let's create a simple microservice. We'll start by creating a file called main.ts
in our project directory. In main.ts
, we'll import the @nestjs/common
module and the @nestjs/microservices
module. We'll also create a class called Main
and decorate it with the @nestjs/common
@Controller
decorator.
import { Controller, Get } from '@nestjs/common';
import { MessagePattern } from '@nestjs/microservices';
@Controller()
export class Main {
@MessagePattern('add')
add(data: number[]) {
return data.reduce((a, b) => a + b);
}
}
In the Main
class, we've created a method called add
that is decorated with the @nestjs/microservices
@MessagePattern
decorator. The @MessagePattern
decorator tells Nest.js that this method should be invoked when a message with the pattern add
is received. The add
method takes an array of numbers as input and returns the sum of the numbers.
Next, we'll create a file called server.ts
in our project directory. In server.ts
, we'll import the @nestjs/microservices
module and the Main
class. We'll also create a class called Server
and decorate it with the @nestjs/microservices
@Microservice
decorator.
import { Microservice } from '@nestjs/microservices';
import { Main } from './main';
@Microservice()
export class Server {
constructor(private readonly main: Main) {}
}
In the Server
class, we've injected an instance of the Main
class using the @nestjs/microservices
@Inject
decorator. We've also decorated the Server
class with the @nestjs/microservices
@Microservice
decorator. The @Microservice
decorator tells Nest.js that this class is a microservice.
Finally, we'll create a file called package.json
in our project directory. In package.json
, we'll add a script called start
that will start our microservice.
{
"name": "my-microservice",
"version": "1.0.0",
"scripts": {
"start": "nest start"
},
"dependencies": {
"@nestjs/common": "^5.4.0",
"@nestjs/microservices": "^5.4.0"
}
}
Now that we've created our microservice, let's deploy it to a server. We'll use Docker to package our microservice into a container. We'll then use docker-compose to deploy our container to a server.
First, we'll create a file called Dockerfile
in our project directory. In Dockerfile
, we'll use the node:10-alpine
Docker image and specify that our microservice should be run on port 3000
. We'll also copy the files from our project directory into the container and install our dependencies.
FROM node:10-alpine
WORKDIR /usr/src/app
COPY . .
RUN npm install
EXPOSE 3000
CMD ["npm", "start"]
Next, we'll create a file called docker-compose.yml
in our project directory. In docker-compose.yml
, we'll specify that we want to use the Dockerfile
we created and that we want to expose port 3000
.
version: '3'
services:
my-microservice:
build:
context: .
dockerfile: Dockerfile
ports:
- "3000:3000"
Now that we have our Dockerfile
and docker-compose.yml
files, we can deploy our microservice to a server. We'll use the AWS Elastic Container Service (ECS) to deploy our container to AWS.
First, we'll create a file called ecs-params.yml
in our project directory. In ecs-params.yml
, we'll specify the name of our container, the port that our container will be exposed on, and the amount of memory and CPU that our container can use.
version: 1
task_definition:
task_execution_role:
Ref: EcsTaskExecutionRole
container_definitions:
- name: my-microservice
image: my-microservice
portMappings:
- containerPort: 3000
hostPort: 3000
memory: 512
cpu: 256
Now that we have our ecs-params.yml
file, we can create our task definition. We'll create a file called ecs-task-definition.json
in our project directory. In ecs-task-definition.json
, we'll specify the name of our task definition, the IAM role that our task will use, and the container definition that we created in ecs-params.yml
.
{
"family": "my-microservice-task-definition",
"executionRoleArn": "arn:aws:iam::123456789012:role/ecsTaskExecutionRole",
"containerDefinitions": [
{
"name": "my-microservice",
"image": "my-microservice",
"portMappings": [
{
"containerPort": 3000,
"hostPort": 3000
}
],
"memory": 512,
"cpu": 256
}
]
}
Now that we have our task definition, we can register our task definition with ECS. We'll create a file called ecs-register-task-definition.json
in our project directory. In ecs-register-task-definition.json
, we'll specify the name of our task definition and the ecs-task-definition.json
file that we created.
{
"taskDefinition": "my-microservice-task-definition",
"cliInputJson": "file://ecs-task-definition.json"
}
Finally, we can create our service. We'll create a file called ecs-create-service.json
in our project directory. In ecs-create-service.json
, we'll specify the name of our service, the task definition that our service will use, the number of tasks that our service will run, and the load balancer that our service will use.
{
"service": "my-microservice-service",
"taskDefinition": "my-microservice-task-definition",
"desiredCount": 1,
"loadBalancer": {
"elbName": "my-load-balancer",
"targetGroupArn": "arn:aws:elasticloadbalancing:us-east-1:123456789012:targetgroup/my-target-group/abcdef1234567890"
}
}
Now that we have our ecs-create-service.json
file, we can deploy our service. We'll use the AWS Command Line Interface (CLI) to deploy our service. First, we'll use the aws ecs register-task-definition
command to register our task definition.
aws ecs register-task-definition --cli-input-json file://ecs-register-task-definition.json
Next, we'll use the aws ecs create-service
command to create our service.
aws ecs create-service --cli-input-json file://ecs-create-service.json
In this article, we've explored how to develop a microservice using TypeScript and Nest.js. We've looked at the benefits of using TypeScript and Nest.js for microservices. We've also created a simple microservice and deployed it to a server.