.NET 6 AWS Lambda项目启动报错：Invalid URI: 无法解析主机名

问题详情 #

我有一个.NET 6的AWS Lambda项目，launchSettings.json配置如下：

{
  "profiles": {
    "MyProject": {
      "commandName": "Project",
      "launchBrowser": true,
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      },
      "applicationUrl": "https://localhost:56452;http://localhost:56453"
    }
  }
}

运行应用时抛出以下错误：

Invalid URI: The hostname could not be parsed.
   at System.Uri.CreateThis(String uri, Boolean dontEscape, UriKind uriKind, UriCreationOptions& creationOptions)
   at System.Uri..ctor(String uriString, UriKind uriKind)
   at Amazon.Lambda.RuntimeSupport.InternalRuntimeApiClient.<NextAsync>d__13.MoveNext()
   at Amazon.Lambda.RuntimeSupport.RuntimeApiClient.<GetNextInvocationAsync>d__16.MoveNext()
   at Amazon.Lambda.RuntimeSupport.LambdaBootstrap.<InvokeOnceAsync>d__17.MoveNext()
   at Amazon.Lambda.RuntimeSupport.LambdaBootstrap.<RunAsync>d__15.MoveNext()
   at Microsoft.AspNetCore.Hosting.GenericWebHostService.<StartAsync>d__37.MoveNext()
   at Microsoft.Extensions.Hosting.Internal.Host.<StartAsync>d__12.MoveNext()
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.<RunAsync>d__4.MoveNext()
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.<RunAsync>d__4.MoveNext()
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.Run(IHost host)
   at Microsoft.AspNetCore.Builder.WebApplication.Run(String url)
   at Program.<Main>$(String[] args) in <My Solution Path>\Program.cs:line 94

已尝试删除.vs文件夹、管理员模式启动Visual Studio、重启机器，均未解决问题。同事使用相同配置可正常运行，推测问题出在本地环境。

补充：项目Program.cs代码（移除依赖注入部分）：

using Amazon.XRay.Recorder.Handlers.AwsSdk;
using Asp.Versioning;
//using for DI
//using for DI
using Moschen.AwsLambdaAuthenticationHandler;
using Moschen.AwsLambdaAuthenticationHandler.Jwt;
using System.Text.Json;
using System.Text.Json.Serialization;

var environment = Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT");
if (!string.IsNullOrWhiteSpace(environment) && environment != "Local")
{
    AWSSDKHandler.RegisterXRayForAllServices();
}

var builder = WebApplication.CreateBuilder(args);

// Set request timeout
builder.WebHost.UseKestrel(options =>
{
    options.Limits.RequestHeadersTimeout = TimeSpan.FromSeconds(5);
    options.Limits.KeepAliveTimeout = TimeSpan.FromSeconds(5);
});

//Logger
builder.Logging
    .ClearProviders()
    .AddJsonConsole()
    .AddLambdaLogger(new LambdaLoggerOptions
    {
        IncludeCategory = true,
        IncludeLogLevel = true,
        IncludeNewline = true,
        IncludeEventId = true,
        IncludeException = true
    });

builder.Services.AddTransient(s => s.GetRequiredService<ILoggerFactory>().CreateLogger("default"));

builder.Services.AddHttpContextAccessor();

// Add services to the container.
builder.Services
    .AddControllers()
    .AddJsonOptions(options =>
    {
        options.JsonSerializerOptions.PropertyNamingPolicy = JsonNamingPolicy.CamelCase;
        options.JsonSerializerOptions.Converters.Add(new JsonStringEnumConverter(JsonNamingPolicy.CamelCase));
    });

builder.Services
    .AddAuthentication(AwsAuthorizerDefaults.AuthenticationScheme)
    .AddAwsAuthorizer();

builder.Services
    .AddAuthentication(AwsJwtAuthorizerDefaults.AuthenticationScheme)
    .AddJwtAuthorizer(options =>
    {
        options.ExtractClaimsFromToken = true;
    });

// Dependency Injection for the project
//...
//...
//...

builder.Services.AddApiVersioning(options =>
{
    options.ReportApiVersions = false;
    options.ApiVersionReader = new UrlSegmentApiVersionReader();
    options.DefaultApiVersion = new ApiVersion(1);
    options.AssumeDefaultVersionWhenUnspecified = true;
});

builder.Services
    .AddHealthChecks();

// Add AWS Lambda support. When running the application as an AWS Server-less application, Kestrel is replaced
// with a Lambda function contained in the Amazon.Lambda.AspNetCoreServer package, which marshals the request into the ASP.NET Core hosting framework.
builder.Services.AddAWSLambdaHosting(LambdaEventSource.RestApi);

var app = builder.Build();

app.UseHttpsRedirection();
app.UseHealthChecks("/health");

app.UseAuthentication();

app.UseAuthorization();
app.MapControllers();

app.MapGet("/", () => "Welcome to running ASP.NET Core Minimal API on AWS Lambda");

app.Run(); //Exception is thrown from here

解决步骤 #

• 检查并清理冲突环境变量：查看系统环境变量中是否存在AWS_LAMBDA_RUNTIME_API，如果有则临时删除或重命名，重启Visual Studio后重试。这个变量是Lambda运行时专用的，本地调试时被错误设置会导致URI解析失败。
• 修改launchSettings.json强制本地模式：在environmentVariables中添加"AWS_LAMBDA_RUNTIME_API": ""，明确告诉应用本地使用Kestrel而非Lambda运行时：

  "environmentVariables": {
    "ASPNETCORE_ENVIRONMENT": "Development",
    "AWS_LAMBDA_RUNTIME_API": ""
  }
  

• 更新Lambda相关NuGet包：确保Amazon.Lambda.AspNetCoreServer包版本与.NET 6兼容，建议更新到最新稳定版，旧版本可能存在本地调试的URI解析bug。
• 清理项目缓存并重新还原：删除项目根目录下的bin和obj文件夹，执行dotnet clean和dotnet restore命令后重新生成项目。
• 验证hosts文件配置：检查本地hosts文件中是否存在127.0.0.1 localhost的映射，若缺失则添加（需要管理员权限）。

内容的提问来源于stack exchange，提问作者user007