1. 创建一个ASP.NET Core应用程序并在Dockerfile中指定基础镜像

FROM mcr.microsoft.com/dotnet/core/sdk:3.1 AS build-env
WORKDIR /app

COPY . ./
RUN dotnet restore
RUN dotnet publish -c Release -o out

FROM mcr.microsoft.com/dotnet/core/aspnet:3.1
WORKDIR /app
COPY --from=build-env /app/out .

ENV ConnectionString="server=db;port=3306;database=mydb;uid=root;pwd=password"

EXPOSE 80/tcp
ENTRYPOINT ["dotnet", "MyApp.dll"]

2. 创建一个MySQL服务docker-compose.yml文件

version: '3.8'

services:
  db:
    image: mysql:latest
    command: --default-authentication-plugin=mysql_native_password
    environment:
      MYSQL_ROOT_PASSWORD: password
      MYSQL_DATABASE: mydb
    ports:
      - "3306:3306"

3. 在ASP.NET Core应用程序中添加MySQL NuGet包和MySQL连接字符串

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;
using MySql.Data.MySqlClient;

namespace MyApp.Controllers
{
    [ApiController]
    [Route("[controller]")]
    public class SampleController : ControllerBase
    {
        private readonly ILogger _logger;

        public SampleController(ILogger logger)
        {
            _logger = logger;
        }

        [HttpGet]
        public async Task Get()
        {
            string connectionString = Environment.GetEnvironmentVariable("ConnectionString");

            using (MySqlConnection connection = new MySqlConnection(connectionString))
            {
                await connection.OpenAsync();

                using (MySqlCommand command = new MySqlCommand("SELECT COUNT(*) FROM sample_table", connection))
                {
                    object result = await command.ExecuteScalarAsync();
                    return Ok(result);
                }
            }
        }
    }
}

4. 运行docker-compose，然后使用浏览器或curl访问应用程序的端点http://localhost/sample

docker-compose up -d --build