Nest.js integration with Nitric

What we'll be doing

In this guide we will be creating a Nest.js application and deploying it to the cloud using the Nitric CLI.

The Nest.js application will be able to perform CRUD operations on user profiles that will interact with a key value store using the Nitric SDK.

Prerequisites

To complete this guide, here are things you'll need setup ahead of time:

• Node.js
• The Nitric CLI
• An AWS, GCP or Azure account (your choice)

Getting started

To get started we will download the Nest CLI.

npm i -g @nestjs/cli

We can then use the CLI to scaffold our Nest project.

nest new nest-x-nitric

This will create a src directory with the Nest application code and a test file.

Adding a Profile controller

Within our src directory we want to replace the base App controller code with a Profile controller.

import { Controller, Get } from '@nestjs/common'
import { ProfileService } from './profile.service'

@Controller()
export class ProfileController {
  constructor(private readonly profileService: ProfileService) {}

  @Get()
  getProfile(): string {
    return this.profileService.getProfile()
  }
}

Then update the App service with the Profile service.

import { Injectable } from '@nestjs/common'

@Injectable()
export class ProfileService {
  getProfile(): string {
    return 'Hello World!'
  }
}

We will then need to update the imports for the base App module. We will keep this as the AppModule as its going to act as the entrypoint to our application.

import { Module } from '@nestjs/common'
import { ProfileController } from './profile/profile.controller'
import { ProfileService } from './profile/profile.service'

@Module({
  imports: [],
  controllers: [ProfileController],
  providers: [ProfileService],
})
export class AppModule {}

Creating the ProfileService

With that done, we can start creating some routes for interacting with our user profiles. We will be storing the profiles in a key value store which is handled by the Nitric SDK.

yarn add @nitric/sdk

Firstly, we will define our profiles key value store and a Profile type at the top of our ProfileService file. The key value store will have permissions for getting, setting, and deleting as we will be using all those features for our Profile service.

import { Injectable, NotFoundException } from '@nestjs/common';
import { kv } from '@nitric/sdk';

export interface Profile {
  id: string;
  name: string;
  age: number;
}

const profiles = kv<Profile>('profiles').for(
  'getting',
  'setting',
  'deleting',
);

@Injectable()
export class ProfileService {
  ...
}

We can then create some handlers for creating profiles. This will accept a create profile request and return the newly created profile.

@Injectable()
export class ProfileService {
  async createProfile(createProfileReq: Omit<Profile, 'id'>): Promise<Profile> {
    const id: string = uuidv4()

    const profile = { id, ...createProfileReq } as Profile

    await profiles.set(id, profile)

    return profile
  }
}

Our next handler will be getting an individual profile by its id. This will accept an id and will return either the found profile or throw a not found exception.

@Injectable()
export class ProfileService {
  ...

  async getProfile(id: string): Promise<Profile> {
    const profile = await profiles.get(id);

    if (!profile) {
      throw new NotFoundException();
    }

    return profile;
  }
}

The final handler we will write is for deleting an individual profile by its id.

@Injectable()
export class ProfileService {
  ...

  async deleteProfile(id: string): Promise<void> {
    await profiles.delete(id);
  }
}

Adding Nitric

To run the application locally using Nitric, and to eventually deploy the application, we will need to create a nitric.yaml file. This contains the name of the project, and a file path to the main entrypoint to the application.

name: nest-x-nitric
services:
  - match: src/main.ts
    start: yarn dev

We then want to add the http type to our main function, and pass in the Nest.js application. The http wrapper will use the bootstrap function when starting the application and pass it the port.

import { http } from '@nitric/sdk'
import { NestFactory } from '@nestjs/core'
import { AppModule } from './app.module'

async function bootstrap(port: number) {
  const app = await NestFactory.create(AppModule)
  await app.listen(port)
}

http(bootstrap)

Creating the ProfileController

Now that the service is built, we can use the ProfileService with our ProfileController routing. This involves correctly extracting the parameters from the request object to then pass into the services.

import { Controller, Get, Post, Delete, Param, Req } from '@nestjs/common'
import { Profile, ProfileService } from './profile.service'
import { Request } from 'express'

@Controller()
export class ProfileController {
  constructor(private readonly profileService: ProfileService) {}

  @Get('/profile/:id')
  async getProfile(@Param('id') id: string) {
    return await this.profileService.getProfile(id)
  }

  @Post('/profile')
  async createProfile(@Req() req: Request<Omit<Profile, 'id'>>) {
    return await this.profileService.createProfile(req.body)
  }

  @Delete('/profile/:id')
  async deleteProfile(@Param('id') id: string) {
    return await this.profileService.deleteProfile(id)
  }
}

Test locally

We can test that this works by running nitric start.

nitric start

You can use any http client to test the application. The application will be running from a random port, but proxied on port 4001. It is important that http://localhost:4001 correctly wraps your application.

We can test that a create request works by using the following cURL command.

curl  -X POST \
  'http://localhost:4001/profile' \
  --header 'Content-Type: application/json' \
  --data-raw '{
  "name": "Peter Parker",
  "age": 17,
  "homeTown": "Queens, New York City"
}'

It should return something similar to this:

{
  "id": "2cbaeaf5-9339-44c4-a396-606a0d3910d9",
  "name": "Peter Parker",
  "age": 17,
  "homeTown": "Queens, New York City"
}

Using that id we can then make a get request to get the profile (replace the id param with the id from above).

curl http://localhost:4001/profile/2cbaeaf5-9339-44c4-a396-606a0d3910d9

It should return:

{
  "id": "2cbaeaf5-9339-44c4-a396-606a0d3910d9",
  "name": "Peter Parker",
  "age": 17,
  "homeTown": "Queens, New York City"
}

Deploy to the cloud

If you're ready, you can deploy the application to AWS, Azure or Google Cloud.

The application code is ready to deploy as is, however a stack first needs to be defined. Stacks are essentially named deployment targets, which represent instances of your services running in the cloud.

You can create a new stack by running nitric stack new and following the prompts.

nitric stack new

Finally, run the up command to deploy the stack and push your code to the cloud:

nitric up

You can use the URL returned from the up command to make requests to your newly deployed application. If you want to make further changes to your application just run nitric up again and only the difference will be deployed.

When you're done with your application, you can destroy it using the command:

nitric down