using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;

namespace AWSS3Example.Services.AWS
{
  public interface IAWSS3Service
  {
    Task<string> UploadFile(IFormFile formFile);
  }
}

using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Amazon.S3;
using Amazon.S3.Model;

namespace AWSS3Example.Services.AWS
{
  public class AWSS3Service : IAWSS3Service
  {
    private IAmazonS3 _s3Client;
    public AWSS3Service(IAmazonS3 amazonS3)
    {
      _s3Client = amazonS3;
    }
    public async Task<string> UploadFile(IFormFile formFile)
    {
      var location = $"uploads/{formFile.FileName}";
      using (var stream = formFile.OpenReadStream())
      {
        var putRequest = new PutObjectRequest
        {
          Key = location,
          BucketName = "upload-test-berv",
          InputStream = stream,
          AutoCloseStream = true,
          ContentType = formFile.ContentType
        };
        var response = await _s3Client.PutObjectAsync(putRequest);
        return location;
      }
    }
  }
}

using System.Threading.Tasks;
using AWSS3Example.Services.AWS;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Http;

namespace AWSS3Example.Controllers
{
  [ApiController]
  [Route("api/[controller]")]
  public class SThreeController : ControllerBase
  {
    private readonly IAWSS3Service _awsS3Service;
    public SThreeController(IAWSS3Service awsS3Service)
    {
      _awsS3Service = awsS3Service;
    }

    [HttpPost("upload")]
    public async Task<IActionResult> Upload([FromForm] IFormFile file)
    {
      var result = await _awsS3Service.UploadFile(uploadFile.File);
      return Ok(new
      {
        path = result
      });
    }
  }
}

using Amazon.S3;
using AWSS3Example.Services.AWS;
// ... the rest of another using
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

namespace AWSS3Example
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            // the rest of another register service ...
            services.AddScoped<IAWSS3Service, AWSS3Service>();
            services.AddAWSService<IAmazonS3>();
            // the rest of another register service ...
            services.AddControllers();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            // the rest of your configure, no need to modify this...
        }
    }
}