ArgumentNullException when not setting Name in IHealthCheck

[andrecarlucci]

Hi guys,

You will get an ArgumentNullException when creating your own HealthCheck handler without setting something to its Name property:

Microsoft.AspNetCore.Server.Kestrel:Error: Connection id "0HLHTL2OE18LU", Request id "0HLHTL2OE18LU:00000002": An unhandled exception was thrown by the application.

System.ArgumentNullException: Value cannot be null.
Parameter name: key
   at System.Collections.Generic.Dictionary`2.TryInsert(TKey key, TValue value, InsertionBehavior behavior)
   at System.Collections.Generic.Dictionary`2.set_Item(TKey key, TValue value)
   at Microsoft.Extensions.Diagnostics.HealthChecks.HealthCheckService.CheckHealthAsync(Func`2 predicate, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Diagnostics.HealthChecks.HealthCheckMiddleware.InvokeAsync(HttpContext httpContext)
   at Microsoft.AspNetCore.Builder.Extensions.MapMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Server.IISIntegration.IISMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.ProcessRequests[TContext](IHttpApplication`1 application)

As the exception is not helpful at all, it took me a little while to figure it out (I had to look at the source code).

I believe the solution for this would be:

• A specific exception for this
  or
• The default name is the class full name or whatever

Thanks!

[mkArtakMSFT]

Thanks for contacting us, @andrecarlucci.
@rynowak, seems like something we can do in 2.2 timeframe.

[rynowak]

Hi, @andrecarlucci - as of 2.2.0-preview3 the health check doesn't define its own name, it's passed in (and null-checked) when the check is registered.