.net core ocelot配置文件中的环境变量

我有多个微服务，客户可以通过

Ocelot

网关访问这些微服务。在配置文件中，有用于指定下游主机和端口的属性。必须对每条路线执行此操作

问题是，如果服务的主机名或端口发生更改，我将不得不修改与此特定服务关联的每个路由

所以，问题是，是否可以在

ocelot.json

配置文件中引入ENV变量？在这种情况下，我将不得不修改只有一个环境变量和所有相关的路线将受到影响

这是我当前的配置文件（我使用的是

docker compose

，因此服务名称被用作主机）：

我想要的是：

"Routes": [
    {
      "UpstreamPathTemplate": "/api/v1/signIn",
      "DownstreamPathTemplate": "/api/v1/signIn",
      "DownstreamScheme": "http",
      "DownstreamHostAndPorts": [
        {
          "Host": {SERVICE_HOST},
          "Port": {SERVICE_PORT}
        }
      ],
      "SwaggerKey": "Identity"
    },
    {
      "UpstreamPathTemplate": "/api/v1/validate",
      "DownstreamPathTemplate": "/api/v1/validate",
      "DownstreamScheme": "http",
      "DownstreamHostAndPorts": [
        {
          "Host": {SERVICE_HOST},
          "Port": {SERVICE_PORT}
        }
      ],
      "SwaggerKey": "Identity"
    },

---

我能够用

PostConfigure

扩展方法实现这个缺失的功能。在我的例子中，我更喜欢将占位符配置放在

Ocelot.json

中，但您可以更改代码以查看

IConfiguration

而不是使用

GlobalHosts

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

public static class FileConfigurationExtensions
{
    public static IServiceCollection ConfigureDownstreamHostAndPortsPlaceholders(
        this IServiceCollection services,
        IConfiguration configuration)
    {
        services.PostConfigure<FileConfiguration>(fileConfiguration =>
        {
            var globalHosts = configuration
                .GetSection($"{nameof(FileConfiguration.GlobalConfiguration)}:Hosts")
                .Get<GlobalHosts>();

            foreach (var route in fileConfiguration.Routes)
            {
                ConfigureRote(route, globalHosts);
            }
        });

        return services;
    }

    private static void ConfigureRote(FileRoute route, GlobalHosts globalHosts)
    {
        foreach (var hostAndPort in route.DownstreamHostAndPorts)
        {
            var host = hostAndPort.Host;
            if (host.StartsWith("{") && host.EndsWith("}"))
            {
                var placeHolder = host.TrimStart('{').TrimEnd('}');
                if (globalHosts.TryGetValue(placeHolder, out var uri))
                {
                    route.DownstreamScheme = uri.Scheme;
                    hostAndPort.Host = uri.Host;
                    hostAndPort.Port = uri.Port;
                }
            }
        }
    }
}

用法：

public void ConfigureServices(IServiceCollection services)
{
    ...
    services.AddOcelot();
    services.ConfigureDownstreamHostAndPortsPlaceholders(Configuration);
}

Ocelot.json

{
  "Routes": [
    {
      "UpstreamPathTemplate": "/my-resource",
      "UpstreamHttpMethod": [ "POST" ],
      "DownstreamPathTemplate": "/my/resource",
      "DownstreamHostAndPorts": [
        {
          "Host": "{MyService}"
        }
      ]
    }
  ],
  "GlobalConfiguration": {
    "BaseUrl": "https://localhost:5000",
    "Hosts": {
      "MyService": "http://localhost:3999"
    }
  }
} 

---

Ocelot中缺少此功能，但将非常有用。我还没有尝试过，但我认为可以在

IConfiguration上使用
PostConfigure
扩展方法解决这个问题
public void ConfigureServices(IServiceCollection services)
{
    ...
    services.AddOcelot();
    services.ConfigureDownstreamHostAndPortsPlaceholders(Configuration);
}

{
  "Routes": [
    {
      "UpstreamPathTemplate": "/my-resource",
      "UpstreamHttpMethod": [ "POST" ],
      "DownstreamPathTemplate": "/my/resource",
      "DownstreamHostAndPorts": [
        {
          "Host": "{MyService}"
        }
      ]
    }
  ],
  "GlobalConfiguration": {
    "BaseUrl": "https://localhost:5000",
    "Hosts": {
      "MyService": "http://localhost:3999"
    }
  }
}