GoogleCloud Pub/Sub with dotNET8 WebAPI producer

1. Create Google Cloud Pub/Sub service

Google Cloud Project: You'll need a Google Cloud Project, if you don't have one, create one at https://console.cloud.google.com

Pub/Sub API Enabled: Make sure the Pub/Sub API is enabled in your project. You can check this or enable it in the "APIs & Services" section of the Google Cloud Console

We first have to log in to Google Cloud Service

We have to search for Pub/Sub service

1.1. Create a Topic

We press CREATE TOPIC button

We input the topic name an press the CREATE button

We verify the new topic and the corresponding subscription were created

1.2. Create a Service Account

We first navigate to the IAM and Admin service

We select the Service Account option in the left hand side menu, then we press the CREATE SERVICE ACCOUNT button

We input the Service Account details and we press the CREATE AND CONTINUE button

We grant the permission to the service account

Once we granted the permissions we press the Continue button

We finally press the Done button

We verify our new service accoung. We press on the email link

We also create a new Key with a JSON format. For this porpuse we click on the Keys tab

Then we press Create new key option and we select the JSON option in the subsequent dialog box

We can see in the download folder the JSON credentials file downloaded from Google Cloud Service Account

1.3. Set Environment Variable

We run the application to edit the environmental variables

We have to create a new environmental variable called GOOGLE_APPLICATION_CREDENTIALS

This variable have to point to the path where we have placed the JSON key file for our Google Cloud Service Account

2. Create a .NET8 WebAPI with VSCode

Creating a .NET 8 Web API using Visual Studio Code (VSCode) and the .NET CLI is a straightforward process

This guide assumes you have .NET 8 SDK, VSCode, and the C# extension for VSCode installed. If not, you'll need to install these first

Step 1: Install .NET 8 SDK

Ensure you have the .NET 8 SDK installed on your machine: https://dotnet.microsoft.com/es-es/download/dotnet/8.0

You can check your installed .NET versions by opening a terminal and running:

dotnet --list-sdks

If you don't have .NET 8 SDK installed, download and install it from the official .NET download page

Step 2: Create a New Web API Project

Open a terminal or command prompt

Navigate to the directory where you want to create your new project

Run the following command to create a new Web API project:

dotnet new webapi -n GooglePubSubSenderApi

This command creates a new directory with the project name, sets up a basic Web API project structure, and restores any necessary packages

Step 3: Open the Project in VSCode

Once the project is created, you can open it in VSCode by navigating into the project directory and running:

code .

This command opens VSCode in the current directory, where . represents the current directory

3. Load project dependencies

We run this command to load the project library

dotnet add package Google.Cloud.PubSub.V1

4. Create the project structure

5. Create the Controller

using System.Threading.Tasks;
using Google.Cloud.PubSub.V1;
using Microsoft.AspNetCore.Mvc;

namespace PubSubSenderApi.Controllers
{
    public class MessageDto
    {
        public string? Body { get; set; }
        public string? Priority { get; set; }
    }

    [ApiController]
    [Route("api/[controller]")]
    public class PubSubController : ControllerBase
    {
        private static string projectId = "XXXXXXXXXX"; // Replace with your Google Cloud project ID
        private static string topicId = "mytopic"; // Replace with your topic ID

        private static PublisherServiceApiClient publisher;

        static PubSubController()
        {
            publisher = PublisherServiceApiClient.Create();
        }

        [HttpPost("send")]
        public async Task<ActionResult> SendMessage([FromBody] MessageDto messageDto)
        {
            TopicName topicName = new TopicName(projectId, topicId);

            PubsubMessage pubsubMessage = new PubsubMessage
            {
                Data = Google.Protobuf.ByteString.CopyFromUtf8(messageDto.Body),
                Attributes =
                {
                    { "priority", messageDto.Priority }
                }
            };

            await publisher.PublishAsync(topicName, new[] { pubsubMessage });

            return Ok($"Sent message: {messageDto.Body}, Priority: {messageDto.Priority}");
        }
    }
}

6. Modify the application middleware(program.cs)

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.OpenApi.Models;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddControllers();

// Add Swagger
builder.Services.AddSwaggerGen(c =>
{
    c.SwaggerDoc("v1", new OpenApiInfo { Title = "ServiceBusSenderApi", Version = "v1" });
});

var app = builder.Build();

// Configure the HTTP request pipeline.
app.UseRouting();

// Enable middleware to serve generated Swagger as a JSON endpoint.
app.UseSwagger();

// Enable middleware to serve swagger-ui (HTML, JS, CSS, etc.), specifying the Swagger JSON endpoint.
app.UseSwaggerUI(c =>
{
    c.SwaggerEndpoint("/swagger/v1/swagger.json", "ServiceBusSenderApi v1");
});

app.UseAuthorization();

app.MapControllers();

app.Run();

7. Run and Test the application

We execute the following command to run the application

dotnet run

We can verify the API docs with Swagger OpenAPI

luiscoco/GoogleCloud_Pub_Sub_with_dotNET8_WebAPI_producer