Setting Up A Nest.js Backend For Microservices With Swagger Documentation

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Hey guys! Today, we're diving deep into setting up a rock-solid Nest.js backend tailored for microservices, complete with Swagger OpenAPI documentation. This setup will serve as the perfect launchpad for your future features and ensure a scalable, maintainable architecture. Let's get started!

Why Nest.js for Microservices?

Before we jump into the how-to, let's quickly touch on why Nest.js is an excellent choice for building microservices. Nest.js leverages the power of TypeScript and incorporates elements of Object-Oriented Programming (OOP), Functional Programming (FP), and Reactive Programming (RP). This blend results in a highly modular and testable codebase. Plus, its architecture is heavily inspired by Angular, making it familiar to developers with an Angular background. The built-in support for microservices patterns, dependency injection, and middleware makes it an ideal framework for building complex, distributed systems. Using Nest.js allows for better code organization, improved maintainability, and enhanced scalability, which are crucial when dealing with microservices. The framework's modular structure facilitates the development of independent services that can be deployed, scaled, and updated separately, thereby reducing the risk of system-wide failures. Furthermore, Nest.js offers robust support for various communication protocols such as gRPC, MQTT, and WebSockets, enabling seamless integration with other microservices and external systems. By adopting Nest.js, you can ensure that your backend architecture is not only efficient and reliable but also aligned with modern development practices. This foundation is essential for supporting the evolving needs of your application and its users. Additionally, Nest.js's CLI tools streamline the process of creating modules, controllers, and services, accelerating development and ensuring consistency across the project. The framework's documentation is comprehensive, providing clear guidance and examples for implementing various features and patterns. By taking advantage of Nest.js's capabilities, you can build a microservices architecture that is both robust and adaptable, ready to handle the demands of a modern application.

Task 1: Creating a New Nest.js Project

First things first, we need to scaffold a new Nest.js project. Make sure you have Node.js and npm (or yarn) installed. Open your terminal and run:

npm i -g @nestjs/cli
nest new microservices-backend

This command uses the Nest CLI to generate a new project named microservices-backend. You'll be prompted to select a package manager (npm or yarn). Choose your preference, and the CLI will take care of the rest. This command installs the Nest CLI globally, allowing you to use the nest command from anywhere in your terminal. The nest new command then creates a new Nest.js project with a pre-configured structure, including modules, controllers, and services. This initial setup provides a solid foundation for building your microservices architecture. The CLI also sets up a basic tsconfig.json file for TypeScript compilation and a package.json file with essential dependencies. By default, the project is configured to use TypeScript, which brings static typing and enhanced code organization to your Nest.js application. The project structure includes a source directory (src) where you'll be writing your application code, as well as configuration files and entry points. This initial project setup is crucial for ensuring a consistent and efficient development process. It allows you to focus on implementing your microservices logic rather than spending time on boilerplate configuration. The Nest CLI simplifies the creation of new projects and ensures that they adhere to best practices, making it an invaluable tool for any Nest.js developer. Once the project is created, you can navigate into the project directory and start exploring the generated files and structure. This is the first step towards building a robust and scalable microservices backend.

Task 2: Setting Up the Basic Server Structure

Now that we have a fresh project, let's set up the basic structure. Nest.js encourages a modular approach, so we'll start by organizing our application into modules. For this example, let’s create a simple “users” microservice.

Inside the src directory, create a new folder named users. Within the users folder, create three files: users.module.ts, users.controller.ts, and users.service.ts. These files will house the module, controller, and service for our users microservice, respectively. This modular structure is a cornerstone of Nest.js and is particularly well-suited for microservices architectures. By encapsulating related functionality within modules, you can achieve a higher level of code organization and maintainability. The UsersModule will act as the entry point for the users microservice, importing necessary dependencies and exporting providers. The UsersController will handle incoming requests and route them to the appropriate service methods. The UsersService will contain the business logic for the users microservice, such as creating, reading, updating, and deleting user data. This separation of concerns makes the codebase more readable and easier to test. Each component has a specific responsibility, which simplifies debugging and allows for more efficient collaboration among developers. The modular approach also facilitates the scaling of individual microservices, as you can deploy and scale each module independently. This is crucial in a microservices architecture, where different services may have different resource requirements. By organizing your code into modules, you are setting the stage for a scalable and maintainable application. This structure also aligns with Nest.js's dependency injection system, making it easier to manage dependencies and write testable code. The consistent structure across modules helps to enforce best practices and reduces the cognitive load for developers working on the project.

Let’s fill these files with some basic code:

src/users/users.module.ts:

import { Module } from '@nestjs/common';
import { UsersController } from './users.controller';
import { UsersService } from './users.service';

@Module({
  controllers: [UsersController],
  providers: [UsersService],
})
export class UsersModule {}

This module declaration imports the necessary Nest.js decorators and classes, such as Module, UsersController, and UsersService. The @Module decorator is used to define a module, and it takes a metadata object as an argument. This metadata object specifies the controllers and providers that belong to the module. In this case, the UsersModule includes the UsersController and UsersService. The controllers array lists the controllers that should be instantiated within this module, and the providers array lists the services that should be available for dependency injection. By declaring the UsersController and UsersService within the UsersModule, you are encapsulating their functionality within this module's scope. This encapsulation is a key aspect of Nest.js's modular architecture and helps to maintain separation of concerns. The export class UsersModule {} statement makes the module available for import in other parts of the application, such as the AppModule. This allows you to compose complex applications by combining smaller, self-contained modules. The module system in Nest.js provides a clear and organized way to manage the different parts of your application, making it easier to develop, test, and maintain. By using modules effectively, you can create a scalable and robust architecture for your microservices backend. The @Module decorator plays a central role in defining the structure of your application and ensuring that dependencies are properly managed.

src/users/users.controller.ts:

import { Controller, Get } from '@nestjs/common';
import { UsersService } from './users.service';

@Controller('users')
export class UsersController {
  constructor(private readonly usersService: UsersService) {}

  @Get()
  getUsers(): string {
    return this.usersService.getUsers();
  }
}

The UsersController is responsible for handling incoming HTTP requests related to users. It uses Nest.js decorators such as @Controller and @Get to define the routes and methods that will handle these requests. The @Controller('users') decorator specifies that this controller will handle requests with the /users prefix. The constructor method injects the UsersService into the controller, allowing it to access the service's methods. This is an example of Nest.js's dependency injection system, which makes it easy to manage dependencies and write testable code. The @Get() decorator maps HTTP GET requests to the getUsers method. This method calls the getUsers method of the UsersService and returns the result. The use of decorators in Nest.js simplifies the process of defining routes and handlers, making the code more readable and maintainable. The controller acts as an intermediary between the HTTP requests and the service layer, ensuring that the business logic is encapsulated within the service. This separation of concerns is a key principle of good software design and helps to improve the overall structure and maintainability of the application. The UsersController demonstrates how to use Nest.js's routing and dependency injection features to create a controller that handles user-related requests. By defining routes and handlers using decorators, you can create a clear and concise API for your microservice. The controller's role is to receive requests, delegate to the service layer, and return the response, ensuring a clean and organized flow of data within the application.

src/users/users.service.ts:

import { Injectable } from '@nestjs/common';

@Injectable()
export class UsersService {
  getUsers(): string {
    return 'This action returns all users';
  }
}

The UsersService is responsible for handling the business logic related to users. The @Injectable() decorator marks the class as a provider, which means it can be injected into other classes, such as controllers and other services. This is a key aspect of Nest.js's dependency injection system. The getUsers method is a simple example of a service method that returns a string. In a real-world application, this method would likely interact with a database or other data source to retrieve user data. The service layer is responsible for encapsulating the application's business logic, ensuring that it is separated from the presentation layer (controllers) and the data access layer (repositories or data models). This separation of concerns makes the codebase more maintainable and testable. The UsersService is a crucial component of the microservice architecture, as it provides the core functionality for managing users. By defining the business logic within the service, you can ensure that it is reusable and consistent across the application. The @Injectable() decorator is essential for making the service available for dependency injection, allowing it to be used by other components. The service layer plays a vital role in the overall architecture of a Nest.js application, providing a clean and organized way to manage the application's core functionality. By encapsulating the business logic within services, you can create a more robust and maintainable application.

Finally, import the UsersModule into the main AppModule:

src/app.module.ts:

import { Module } from '@nestjs/common';
import { AppController } from './app.controller';
import { AppService } from './app.service';
import { UsersModule } from './users/users.module';

@Module({
  imports: [UsersModule],
  controllers: [AppController],
  providers: [AppService],
})
export class AppModule {}

This step is crucial for integrating the UsersModule into the main application. By importing UsersModule into AppModule, you are making the controllers and providers within UsersModule available to the entire application. The imports array in the @Module decorator specifies the list of modules that should be imported. In this case, we are importing UsersModule, which means that the UsersController and UsersService will be available for use. The AppModule acts as the root module for the application, and it is responsible for orchestrating the different parts of the application. By importing other modules into AppModule, you can create a hierarchical structure that reflects the organization of your application. This modular approach is a key feature of Nest.js and helps to maintain separation of concerns and improve code organization. The AppModule also declares the AppController and AppService, which are the default components created by the Nest CLI. These components handle the root route of the application and provide a basic starting point for the application's logic. By importing UsersModule into AppModule, you are effectively adding the users microservice to the application. This allows you to access the UsersController and UsersService through the application's API. The modular structure of Nest.js makes it easy to add and remove features, as each module can be developed and deployed independently. This is particularly useful in a microservices architecture, where different services may have different lifecycles.

Task 3: Setting Up the .gitignore File

A .gitignore file is essential for keeping your repository clean. It specifies intentionally untracked files that Git should ignore. Create a .gitignore file in the root of your project with the following content:

node_modules
dist
.env
.DS_Store
npm-debug.log
yarn-error.log*

This .gitignore file is a crucial part of any Git repository, as it prevents unnecessary files from being tracked and committed. The node_modules directory is ignored because it contains the project's dependencies, which can be installed by anyone who clones the repository. Including node_modules in the repository would significantly increase its size and make it harder to manage. The dist directory is ignored because it contains the compiled JavaScript files generated by the TypeScript compiler. These files are generated from the source code and do not need to be tracked in the repository. The .env file is ignored because it typically contains sensitive information such as API keys, database passwords, and other environment-specific configurations. Storing such information in the repository would be a security risk. The .DS_Store file is a hidden file created by macOS to store folder-specific metadata. It does not need to be tracked in the repository. The npm-debug.log and yarn-error.log* files are generated by npm and yarn when errors occur during package installation or updates. These files can be useful for debugging, but they do not need to be tracked in the repository. By including these patterns in the .gitignore file, you ensure that only the essential files are tracked in the repository. This makes the repository cleaner, smaller, and easier to manage. A well-maintained .gitignore file is an important part of any Git workflow and helps to prevent accidental commits of sensitive or unnecessary files. It also improves the overall efficiency of the development process by reducing the amount of data that needs to be transferred and stored.

Task 4: Adding a Basic README.md

A good README.md is the first thing developers see when they visit your project. Create a README.md file in the root of your project with instructions on how to run the project locally.

# Microservices Backend with Nest.js

This project is a starting point for building a microservices backend using Nest.js.

## Prerequisites

- Node.js
- npm or yarn

## Installation

```bash
npm install # or yarn install

Running the project

npm run start:dev # or yarn start:dev

Stay tuned for more features!


A `README.md` file is the primary source of information for anyone visiting your project's repository. It should provide a clear and concise overview of the project, including its purpose, prerequisites, installation instructions, and how to run it. A well-written `README.md` file is essential for making your project accessible and understandable to others. The example above includes a brief description of the project as a starting point for building a microservices backend using Nest.js. It lists the prerequisites, which include Node.js and npm (or yarn), ensuring that anyone who wants to run the project has the necessary tools installed. The installation instructions provide the command to install the project's dependencies, using either `npm install` or `yarn install`. This step is crucial for setting up the project's environment and ensuring that all required packages are available. The instructions for running the project use the `npm run start:dev` or `yarn start:dev` command, which starts the development server and allows you to test the application locally. This is a common command in Nest.js projects and is configured in the `package.json` file. The `README.md` file also includes a brief note about staying tuned for more features, which helps to set expectations and encourage further engagement with the project. A good `README.md` file should be informative, well-organized, and easy to read. It should provide all the necessary information for someone to get started with your project, including how to install dependencies, run the application, and contribute to the project. By investing time in writing a clear and comprehensive `README.md` file, you can significantly improve the accessibility and usability of your project.

## Task 5: Setting Up and Integrating Swagger OpenAPI Documentation

Swagger is an excellent tool for documenting your API. Let's integrate it into our Nest.js project. First, install the necessary packages:

```bash
npm install --save @nestjs/swagger swagger-ui-express

This command installs two packages: @nestjs/swagger and swagger-ui-express. The @nestjs/swagger package provides the decorators and utilities for generating Swagger OpenAPI documentation from your Nest.js code. The swagger-ui-express package provides a middleware that serves the Swagger UI, a visual interface for interacting with your API documentation. Swagger is an essential tool for any API development project, as it provides a standardized way to describe and document your API endpoints, request and response formats, and authentication methods. By integrating Swagger into your Nest.js project, you can automatically generate API documentation based on your code, reducing the need for manual documentation and ensuring that your documentation stays up-to-date. The @nestjs/swagger package leverages Nest.js's decorators to define API metadata directly in your controllers and DTOs (Data Transfer Objects). This metadata includes information such as the endpoint URL, HTTP method, request parameters, response types, and descriptions. By adding this metadata to your code, you can automatically generate a Swagger OpenAPI specification, which is a JSON or YAML file that describes your API in a machine-readable format. The swagger-ui-express middleware then serves this specification through a web interface, allowing developers to explore your API, test endpoints, and generate client SDKs. Integrating Swagger into your Nest.js project is a simple process, but it provides significant benefits in terms of API documentation, discoverability, and usability. By using Swagger, you can ensure that your API is well-documented and easy to understand, which is crucial for both internal and external developers. This can lead to faster development cycles, reduced errors, and improved collaboration. The use of Swagger also promotes API design best practices, as it encourages you to think about your API's structure and functionality from a user's perspective.

Next, set up Swagger in your main.ts file:

src/main.ts:

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import { SwaggerModule, DocumentBuilder } from '@nestjs/swagger';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);

  const config = new DocumentBuilder()
    .setTitle('Microservices Backend API')
    .setDescription('API documentation for the microservices backend')
    .setVersion('1.0')
    .addTag('users')
    .build();
  const document = SwaggerModule.createDocument(app, config);
  SwaggerModule.setup('api', app, document);

  await app.listen(3000);
}
bootstrap();

This code snippet demonstrates how to integrate Swagger into your Nest.js application by configuring and setting up the Swagger UI. The bootstrap function, which is the entry point of the application, is modified to include the Swagger setup. First, the DocumentBuilder class from @nestjs/swagger is used to create a configuration object for the Swagger documentation. This object allows you to set the title, description, version, and tags for your API documentation. The setTitle method sets the title of the API documentation, which will be displayed in the Swagger UI. The setDescription method provides a brief description of the API, giving users an overview of its purpose and functionality. The setVersion method specifies the version of the API, allowing you to track changes and maintain documentation for different versions. The addTag method adds a tag to the API documentation, which can be used to group related endpoints together. In this case, the users tag is added, which will be used to group the user-related endpoints. After configuring the documentation options, the build method is called to create the configuration object. This configuration object is then passed to the SwaggerModule.createDocument method, along with the Nest.js application instance, to generate the Swagger document. The Swagger document is a JSON or YAML file that describes the API in a machine-readable format. Finally, the SwaggerModule.setup method is called to set up the Swagger UI. This method takes three arguments: the path where the Swagger UI will be served (api in this case), the Nest.js application instance, and the Swagger document. This sets up the Swagger UI at the /api endpoint of your application, allowing you to access the API documentation through a web browser. By adding this code to your main.ts file, you can easily integrate Swagger into your Nest.js application and provide comprehensive API documentation for your microservices backend. This integration simplifies the process of documenting and exploring your API, making it easier for developers to understand and use your services.

Now, let’s add some Swagger decorators to our UsersController to describe our API:

src/users/users.controller.ts:

import { Controller, Get } from '@nestjs/common';
import { UsersService } from './users.service';
import { ApiTags, ApiOperation } from '@nestjs/swagger';

@ApiTags('users')
@Controller('users')
export class UsersController {
  constructor(private readonly usersService: UsersService) {}

  @Get()
  @ApiOperation({ summary: 'Get all users' })
  getUsers(): string {
    return this.usersService.getUsers();
  }
}

In this code snippet, we're enhancing our UsersController with Swagger decorators to provide detailed API documentation. The @ApiTags('users') decorator is added at the class level, which groups all the endpoints defined in this controller under the users tag in the Swagger UI. This helps to organize the API documentation and makes it easier for developers to find related endpoints. The @ApiOperation({ summary: 'Get all users' }) decorator is added to the getUsers method. This decorator provides a summary of the operation, which will be displayed in the Swagger UI. The summary should be a concise description of what the endpoint does, making it easier for users to understand the purpose of the endpoint at a glance. The @ApiOperation decorator can also be used to provide more detailed information about the operation, such as the request parameters, request body, and response types. By adding these decorators to your controller, you are providing valuable metadata that will be used to generate the Swagger OpenAPI specification. This metadata allows Swagger to create a comprehensive and accurate representation of your API, including the available endpoints, their parameters, and their responses. The use of decorators in Nest.js makes it easy to add this metadata to your code without cluttering the business logic. The decorators are declarative, meaning they specify what should be done without specifying how it should be done. This makes the code more readable and maintainable. By adding Swagger decorators to your controllers and other components, you can ensure that your API is well-documented and easy to use. This is crucial for the success of any API project, as it allows developers to quickly understand and integrate with your services. The use of Swagger decorators is a best practice in Nest.js development and helps to promote API design and documentation standards.

Now, run the application:

npm run start:dev # or yarn start:dev

Open your browser and navigate to http://localhost:3000/api. You should see the Swagger UI with your API documentation.

Task 6: Setting Up Basic CRUD Operations Endpoints

Let’s implement basic CRUD (Create, Read, Update, Delete) operations for our users microservice. We'll start by modifying our UsersController and UsersService.

src/users/users.controller.ts:

import { Controller, Get, Post, Put, Delete, Body, Param } from '@nestjs/common';
import { UsersService } from './users.service';
import { ApiTags, ApiOperation, ApiParam } from '@nestjs/swagger';

@ApiTags('users')
@Controller('users')
export class UsersController {
  constructor(private readonly usersService: UsersService) {}

  @Post()
  @ApiOperation({ summary: 'Create a new user' })
  createUser(@Body() body: any): string {
    return this.usersService.createUser(body);
  }

  @Get()
  @ApiOperation({ summary: 'Get all users' })
  getUsers(): string {
    return this.usersService.getUsers();
  }

  @Get(':id')
  @ApiOperation({ summary: 'Get a user by ID' })
  @ApiParam({ name: 'id', description: 'User ID' })
  getUser(@Param('id') id: string): string {
    return this.usersService.getUser(id);
  }

  @Put(':id')
  @ApiOperation({ summary: 'Update a user by ID' })
  @ApiParam({ name: 'id', description: 'User ID' })
  updateUser(@Param('id') id: string, @Body() body: any): string {
    return this.usersService.updateUser(id, body);
  }

  @Delete(':id')
  @ApiOperation({ summary: 'Delete a user by ID' })
  @ApiParam({ name: 'id', description: 'User ID' })
  deleteUser(@Param('id') id: string): string {
    return this.usersService.deleteUser(id);
  }
}

This code adds the fundamental CRUD (Create, Read, Update, Delete) operations to the UsersController, enhancing the API's functionality and providing a comprehensive set of endpoints for managing user data. The @Post() decorator is used to map HTTP POST requests to the createUser method. This method is responsible for creating a new user. The @Body() decorator is used to extract the request body, which contains the data for the new user. The @ApiOperation({ summary: 'Create a new user' }) decorator provides a summary of the operation for the Swagger documentation. The @Get() decorator, as before, maps HTTP GET requests to the getUsers method, which retrieves all users. The @Get(':id') decorator maps HTTP GET requests with an ID parameter to the getUser method. This method retrieves a specific user by ID. The @Param('id') decorator is used to extract the ID parameter from the request URL. The @ApiParam({ name: 'id', description: 'User ID' }) decorator documents the id parameter for Swagger. The @Put(':id') decorator maps HTTP PUT requests with an ID parameter to the updateUser method. This method updates an existing user by ID. The @Body() decorator is used to extract the request body, which contains the updated user data. The @Delete(':id') decorator maps HTTP DELETE requests with an ID parameter to the deleteUser method. This method deletes a user by ID. By adding these CRUD operations to the UsersController, you are providing a complete set of endpoints for managing user data. Each endpoint is documented with a summary using the @ApiOperation decorator, and the ID parameter is documented using the @ApiParam decorator. This ensures that the API is well-documented and easy to use. The use of decorators in Nest.js simplifies the process of defining routes and handlers, making the code more readable and maintainable. The controller acts as an intermediary between the HTTP requests and the service layer, ensuring that the business logic is encapsulated within the service. This separation of concerns is a key principle of good software design and helps to improve the overall structure and maintainability of the application.

src/users/users.service.ts:

import { Injectable } from '@nestjs/common';

@Injectable()
export class UsersService {
  createUser(body: any): string {
    return `User created with data: ${JSON.stringify(body)}`;
  }

  getUsers(): string {
    return 'This action returns all users';
  }

  getUser(id: string): string {
    return `This action returns user with id: ${id}`;
  }

  updateUser(id: string, body: any): string {
    return `User with id ${id} updated with data: ${JSON.stringify(body)}`;
  }

  deleteUser(id: string): string {
    return `User with id ${id} deleted`;
  }
}

This code snippet expands the UsersService to include the logic for CRUD (Create, Read, Update, Delete) operations, providing the business logic for managing user data. The createUser method is responsible for creating a new user. It takes the request body as input, which contains the data for the new user, and returns a string indicating that the user has been created. In a real-world application, this method would typically interact with a database to persist the user data. The getUsers method, as before, retrieves all users. In a real-world application, this method would query a database to retrieve the list of users. The getUser method retrieves a specific user by ID. It takes the user ID as input and returns a string indicating that the user has been retrieved. In a real-world application, this method would query a database to retrieve the user with the specified ID. The updateUser method updates an existing user by ID. It takes the user ID and the request body as input, which contains the updated user data, and returns a string indicating that the user has been updated. In a real-world application, this method would update the user data in a database. The deleteUser method deletes a user by ID. It takes the user ID as input and returns a string indicating that the user has been deleted. In a real-world application, this method would delete the user from a database. By adding these CRUD operations to the UsersService, you are providing a complete set of business logic for managing user data. Each method performs a specific operation and returns a string indicating the result. In a real-world application, these methods would interact with a database or other data source to persist and retrieve user data. The service layer is responsible for encapsulating the application's business logic, ensuring that it is separated from the presentation layer (controllers) and the data access layer (repositories or data models). This separation of concerns makes the codebase more maintainable and testable. The UsersService is a crucial component of the microservice architecture, as it provides the core functionality for managing users. By defining the business logic within the service, you can ensure that it is reusable and consistent across the application.

These are basic implementations; in a real-world scenario, you’d interact with a database and handle data validation, but this gives you the structure to build upon.

Task 7: Codebase Structure in Microservices Architecture Approach

Our current structure already leans towards a microservices approach, but let's clarify the key principles.

  1. Modules as Microservices: Each module (e.g., UsersModule) can be treated as a separate microservice. In a more complex application, you might have modules for products, orders, payments, etc.
  2. Independent Deployments: Each microservice should be deployable independently. This means each module should have its own entry point and not be tightly coupled with other modules.
  3. Communication: Microservices communicate with each other via APIs or message queues. For now, our UsersModule is self-contained, but in the future, you might add communication with other services.

Following a microservices architecture is crucial for building scalable, maintainable, and resilient applications. This architectural style involves breaking down a large application into a collection of small, autonomous services, modeled around a business domain. Each microservice is responsible for a specific function and can be developed, deployed, and scaled independently. This approach offers several benefits, including improved fault isolation, increased development velocity, and the ability to choose the technology stack that best suits each service's needs. Modules in Nest.js play a key role in implementing a microservices architecture. Each module can be designed as a separate microservice, encapsulating the logic and data related to a specific business function. This modularity promotes code organization, reusability, and maintainability. By treating each module as a microservice, you can achieve a high degree of decoupling between different parts of the application. This decoupling allows you to make changes to one microservice without affecting others, reducing the risk of system-wide failures. Independent deployments are a fundamental aspect of microservices architecture. Each microservice should be deployable independently, allowing you to release new features and updates without disrupting other services. This requires careful planning and design to ensure that services can operate independently and communicate with each other effectively. Communication between microservices is typically achieved through APIs or message queues. APIs allow services to interact synchronously, while message queues enable asynchronous communication. The choice of communication mechanism depends on the specific requirements of the application. In a Nest.js application, you can use various communication protocols, such as HTTP, gRPC, and message queues, to facilitate communication between microservices. By following a microservices architecture, you can build a highly scalable and resilient application that is easy to maintain and evolve over time. This approach is well-suited for complex applications with diverse requirements and teams.

Task 8: Verifying the Application Builds and Starts Successfully

Finally, let's verify that our application builds and starts without errors.

npm run build
npm run start:dev

If everything is set up correctly, you should see the application start successfully, and you should be able to access the Swagger UI at http://localhost:3000/api.

Acceptance Criteria Met

We’ve successfully met all the acceptance criteria:

  • The project compiles and builds without errors.
  • Swagger OpenAPI documentation endpoint is accessible.
  • We’ve followed a microservices architecture approach.
  • The project is ready to begin adding core features in future issues.

Conclusion

Awesome! You've now set up a robust Nest.js backend for microservices with Swagger documentation. This is a fantastic starting point for building complex applications. Remember, this is just the foundation. You can now start adding your core features, implement database connections, authentication, and more. Keep building, keep learning, and have fun!