.NET 3.1和.NET 6.0之间的依赖注入差异

Question

目前，我们在对Azure功能从.NET 3.1到.NET 6的升级中遇到了意外行为。

使用Singleton实现的httpClient提供的文档ClientProvider注册为Singleton Service。为了执行安全检查，将委托人添加到httpclient中。此消息处理程序检查自定义标头的存在，以及标头值与我们的SecurityContext中的标头值相同。

public class DocumentClientProvider : IDocumentClientProvider
{
    private static HttpClient singletonInstance;
    private static readonly object padlock = new object();

    public DocumentClientProvider(DelegatingHandler messageHandler)
    {
        if (singletonInstance == null)
        {
            lock (padlock)
            {
                if (singletonInstance == null)
                {
                    singletonInstance =
                        new HttpClient(messageHandler);
                }
            }
        }
    }

    public HttpClient GetClient() => singletonInstance;
}

public class MyMessageHandler : DelegatingHandler
{
    private readonly IServiceProvider serviceProvider;

    public MyMessageHandler(IServiceProvider serviceProvider)
    {
        this.serviceProvider = serviceProvider;
    }

    protected override Task<HttpResponseMessage> SendAsync(
        HttpRequestMessage request, System.Threading.CancellationToken cancellationToken)
    {
        var securityContext = serviceProvider.GetRequiredService<ISecurityContext>();

        var requestHeaderValue = request.Headers.GetValues("X-Custom-Header").FirstOrDefault();
        var validHeaderValue = $"{securityContext.ClientId.ToString().ToLower()}";

        if (requestHeaderValue != validHeaderValue)
        {
            var message = $"Value of custom header is {requestHeaderValue} and it should be {validHeaderValue}.";
            throw new Exception(message);
        }

        return base.SendAsync(request, cancellationToken);
    }
}

SecurityContext是一个小型数据类，其中包含有关该功能呼叫者身份的信息，并注册为范围的服务。

public class SecurityContext : ISecurityContext
{
    public Guid ClientId { get; set; }
}

功能只需接收呼叫，通过文档ClientProvider检索HTTPCLIENT并调用端点。

public class Function
{
    private readonly HttpClient httpClient;
    private readonly ISecurityContext securityContext;

    public Function(IDocumentClientProvider documentClientProvider, ISecurityContext securityContext)
    {
        httpClient = documentClientProvider.GetClient();
        this.securityContext = securityContext;
    }

    [FunctionName("Function")]
    public async Task<IActionResult> Run(
        [HttpTrigger(AuthorizationLevel.Anonymous, "get", Route = null)] HttpRequest req,
        ILogger log)
    {
        securityContext.ClientId = Guid.NewGuid();

        string name = req.Query["name"];
        name = name ?? "Dummy";

        var httpRequestMessage = new HttpRequestMessage
        {
            Method = HttpMethod.Get,
            RequestUri = new Uri($"https://www.google.com/search?q={name}"),
            Headers = {
              { "X-Custom-Header", securityContext.ClientId.ToString() }
            }
        };

        var response = await httpClient.SendAsync(httpRequestMessage);

        return new OkObjectResult(response);
    }
}

不同位的连接如下：

builder.Services.AddSingleton<IDocumentClientProvider>(ctx => 
    new DocumentClientProvider(new MyMessageHandler(ctx) { 
        InnerHandler = new HttpClientHandler() 
}));     
builder.Services.AddScoped<ISecurityContext, SecurityContext>();

在.NET 3.1中，该函数按预期工作。在整个函数执行过程中，将委托人中的SecurityContext解析为相同的对象。但是，在.NET 6中，将委托人中的安全性解决方案解决了另一个对象。 SecurityContext中的clientId是一个空的GUID，并且会引发异常。

有人对为什么不同版本的Azure函数具有与依赖注入有关的不同行为有任何见解吗？