Dependency Injection not working with RabitMQ Service Bus with Azure Key Vault Value asp.net core 3.0

Question

I am configuring the service bus with dependency as below

Startup.cs

services.AddSingleton<ServiceBusTransportOptions>(sp => JsonConvert.DeserializeObject<ServiceBusTransportOptions>(Configuration.GetSection("ServiceBus").Value));

The value from the vault is as follows

The configured value from the vault file is as below

secrets.json

{
"ServiceBus": "{\"Transport\": \"RabbitMq\",\"RabbitMq\": {\"Url\": \"rabbitmq://localhost\",\"Username\": \"guest\",\"Password\": \"guest\"}}"
}

Model class

public class ServiceBusTransportOptions : IOptions<ServiceBusTransportOptions>
    {
        public TransportType Transport { get; set; } = TransportType.AzureServiceBus;

        public AzureServiceBusTransportOptions AzureServiceBus { get; set; }

        public RabbitMqTransportOptions RabbitMq { get; set; }

        public ServiceBusTransportOptions Value => this;
    }

The value of var config = _.Resolve<IOptions<ServiceBusTransportOptions>>().Value; is default not mapped with the vault value. So causing a null pointer experception

containerBuilder.Extension.cs

  public static void AddServiceBus(this ContainerBuilder builder,
            string applicationName,
            Action<IContainerBuilderConfigurator> configureMassTransitBuilder,
            Action<IComponentContext, IBusFactoryConfigurator> configureServiceBus)
        {
            builder.Register(
                    _ =>
                    {
                        var config = _.Resolve<IOptions<ServiceBusTransportOptions>>().Value;
                        switch (config.Transport)
                        {
                            case TransportType.AzureServiceBus:
                                return new AzureServiceBusConfigurationProvider(config.AzureServiceBus.Value) as
                                    IServiceBusConfigurationProvider;
                            case TransportType.RabbitMq:
                                return new RabbitMqServiceBusConfigurationProvider(config.RabbitMq.Value);
                            default:
                                return new InMemoryServiceBusConfigurationProvider() as
                                    IServiceBusConfigurationProvider;
                        }

                    })
                .As<IServiceBusConfigurationProvider>()
                .SingleInstance();
        }

Answer 1

No need to manually deserialize. Bind to object model from configuration, and explicitly register the desired type

var configuration = new ConfigurationBuilder()
    .AddJsonFile("secret.json")
    .Build();
//"ConfigurationBinder.Gett<T>" method comes from
// Microsoft.Extensions.Configuration.Binder.dll
ServiceBusTransportOptions options = configuration.GetSection("ServiceBus").Get<ServiceBusTransportOptions>();
services.AddSingleton(options);

And resolve as needed

//...
builder.Register(_ => {
    var config = _.Resolve<ServiceBusTransportOptions>();
    switch (config.Transport) {
        case TransportType.AzureServiceBus:
            return new AzureServiceBusConfigurationProvider(config.AzureServiceBus.Value) as
                IServiceBusConfigurationProvider;
        case TransportType.RabbitMq:
            return new RabbitMqServiceBusConfigurationProvider(config.RabbitMq.Value);
        default:
            return new InMemoryServiceBusConfigurationProvider() as
                IServiceBusConfigurationProvider;
    }
})