配置Ocelot后.NET7本地WeatherForecast接口返回503错误求助

需求背景 #

在仅包含WeatherForecast控制器的.NET7简易API项目中集成Ocelot，实现：

• 所有以/OtherRequest开头的请求路由到外部API respondingdomain.com
• /WeatherForecast请求由本地控制器处理
• 应用运行在5287端口

现有代码与配置 #

Program.cs代码 #

using Microsoft.Extensions.Configuration;
using Ocelot.DependencyInjection;
using Ocelot.Middleware;

var builder = WebApplication.CreateBuilder(args);

// 注册服务
builder.Configuration.AddJsonFile("ocelot.json", optional: true, reloadOnChange: true).Build();
builder.Services.AddOcelot();
builder.Services.AddControllers();

var app = builder.Build();

// 配置HTTP管道
app.UseAuthorization();
app.UseOcelot().Wait();

app.MapControllers();

app.Run();

初始Ocelot.json配置 #

{
  "Routes": [
    {
      "DownstreamPathTemplate": "/OtherRequest/{everything}",
      "DownstreamScheme": "https",
      "DownstreamHostAndPorts": [
        {
          "Host": "respondingdomain.com",
          "Port": 443
        }
      ],
      "DelegatingHandlers": [
        "OcelotLoggingHandler"
      ],
      "UpstreamPathTemplate": "/OtherRequest/{everything}",
      "UpstreamHttpMethod": [ "GET", "POST", "PUT", "DELETE" ],
      "RouteIsCaseSensitive": false
    },
    {
      "DownstreamPathTemplate": "/weatherforecast",
      "DownstreamScheme": "http",
      "DownstreamHostAndPorts": [
        {
          "Host": "localhost",
          "Port": 5287
        }
      ],
      "UpstreamPathTemplate": "/weatherforecast",
      "UpstreamHttpMethod": [ "GET", "POST", "PUT", "DELETE" ],
      "RouteIsCaseSensitive": false

    }
  ]
  
}

尝试添加GlobalConfiguration后的Ocelot.json #

{
  "Routes": [
     {
      "DownstreamPathTemplate": "/OtherRequest/{everything}",
      "DownstreamScheme": "https",
      "DownstreamHostAndPorts": [
        {
          "Host": "respondingdomain.com",
          "Port": 443
        }
      ],
      "DelegatingHandlers": [
        "OcelotLoggingHandler"
      ],
      "UpstreamPathTemplate": "/OtherRequest/{everything}",
      "UpstreamHttpMethod": [ "GET", "POST", "PUT", "DELETE"],
      "RouteIsCaseSensitive": false
    },
    {
      "DownstreamPathTemplate": "/weatherforecast",
      "DownstreamScheme": "http",
      "DownstreamHostAndPorts": [
        {
          "Host": "localhost",
          "Port": 5287
        }
      ],
      "UpstreamPathTemplate": "/weatherforecast",
      "UpstreamHttpMethod": [ "GET", "POST", "PUT", "DELETE" ],
      "RouteIsCaseSensitive": false

    }

  ],
  "GlobalConfiguration":

  {
    "BaseUrl": "http://localhost:5287"
  }

}

WeatherForecast控制器代码 #

namespace ApiManager.Ocelot.Controllers
{
    [ApiController]
    [Route("[controller]")]
    public class WeatherForecastController : ControllerBase
    {
        private static readonly string[] Summaries = new[]
        {
        "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
    };

        private readonly ILogger<WeatherForecastController> _logger;

        public WeatherForecastController(ILogger<WeatherForecastController> logger)
        {
            _logger = logger;
        }

        [HttpGet]
        public IEnumerable<WeatherForecast> Get()
        {
            return Enumerable.Range(1, 5).Select(index => new WeatherForecast
            {
                Date = DateOnly.FromDateTime(DateTime.Now.AddDays(index)),
                TemperatureC = Random.Shared.Next(-20, 55),
                Summary = Summaries[Random.Shared.Next(Summaries.Length)]
            })
            .ToArray();
        }
    }
}

问题现象 #

集成Ocelot后，/WeatherForecast请求返回503错误，但未使用Ocelot时该接口可正常响应。

解决方法 #

核心问题分析 #

为本地接口配置Ocelot路由后，Ocelot会尝试将请求转发到localhost:5287，此时应用本身正在占用该端口，会出现循环请求或端口冲突，导致503错误。同时，未实现的OcelotLoggingHandler委托处理器也可能引发异常。

具体调整步骤 #

1. 删除本地接口的Ocelot路由配置
   本地接口不需要Ocelot转发，直接由MapControllers()处理即可，删除Ocelot.json中关于/weatherforecast的路由节点。

2. 移除未实现的委托处理器
   暂时删除DelegatingHandlers配置，排除不必要的干扰。

3. 保持中间件顺序
   UseOcelot()需放在MapControllers()之前，Ocelot会处理匹配到的外部路由请求，未匹配的请求会自动传递给后续的控制器中间件。

修改后的Ocelot.json #

{
  "Routes": [
    {
      "DownstreamPathTemplate": "/OtherRequest/{everything}",
      "DownstreamScheme": "https",
      "DownstreamHostAndPorts": [
        {
          "Host": "respondingdomain.com",
          "Port": 443
        }
      ],
      "UpstreamPathTemplate": "/OtherRequest/{everything}",
      "UpstreamHttpMethod": [ "GET", "POST", "PUT", "DELETE" ],
      "RouteIsCaseSensitive": false
    }
  ]
}

调整后，/WeatherForecast请求会直接由本地控制器处理，/OtherRequest开头的请求则会被Ocelot转发到指定外部API。

内容的提问来源于stack exchange，提问作者Brokrammer