.NET 8独立进程Azure Functions配置SignalR时依赖注入异常

我在采用独立进程模型的.NET 8 Azure Functions中配置SignalR时遇到错误，错误信息如下：

Exception Unable to resolve service for type 'Microsoft.Azure.SignalR.Management.ServiceManager' while attempting to activate 'PatientNavigationDBAPI.Services.SignalRService'

相关代码如下：

扩展方法代码 #

public static class AzureServiceExtensions
{
     public static IServiceCollection AddAzureServices(this IServiceCollection services)
     {
         //other services
         services.AddSignalR().AddAzureSignalR(Environment.GetEnvironmentVariable(EnvironmentVariable.AzureSignalRConnectionString));
         services.AddScoped<SignalRService>();
         
         return services;
     }
}

Program.cs代码 #

var host = new HostBuilder()
    .ConfigureFunctionsWebApplication(worker =>
    {
        worker.UseNewtonsoftJson(new JsonSerializerSettings
        {
            NullValueHandling = NullValueHandling.Include,
            Formatting = Formatting.Indented,
            ContractResolver = new DefaultContractResolver
            {
                NamingStrategy = new CamelCaseNamingStrategy()
            }
        });
       
    })
    .ConfigureOpenApi()
    .ConfigureServices((host, services) =>
    {
        services.AddAzureServices();
       
    })
    .Build()
    .SeedData();

host.Run();

问题原因 #

你当前只注册了SignalR的基础服务端集成，但ServiceManager属于Azure SignalR Management SDK的专属组件，默认不会被注入到依赖注入容器中，导致DI无法解析该类型来激活SignalRService。

解决方案 #

1. 先确保项目已安装Microsoft.Azure.SignalR.Management NuGet包
2. 修改服务注册代码，手动将ServiceManager注入到DI容器：

更新后的AddAzureServices方法：

public static class AzureServiceExtensions
{
     public static IServiceCollection AddAzureServices(this IServiceCollection services)
     {
         //other services
         services.AddSignalR().AddAzureSignalR(Environment.GetEnvironmentVariable(EnvironmentVariable.AzureSignalRConnectionString));
         
         // 注册ServiceManager到DI容器
         var signalRConnString = Environment.GetEnvironmentVariable(EnvironmentVariable.AzureSignalRConnectionString);
         services.AddSingleton<ServiceManager>(_ => 
             new ServiceManagerBuilder()
                 .WithOptions(opt => opt.ConnectionString = signalRConnString)
                 .Build());
         
         services.AddScoped<SignalRService>();
         
         return services;
     }
}

如果使用的是较新版本的Management SDK，也可以用更简洁的扩展方法：

// 替换上面的ServiceManager注册代码
services.AddAzureSignalRManagement(signalRConnString);

完成以上修改后，依赖注入容器就能正常解析ServiceManager，从而成功激活SignalRService。

内容的提问来源于stack exchange，提问作者Sameer Tanveer