v3.0.1, ArgumentNullException if Connection String is missing

[dstj]

(Reboot of #79)

In Profiler v3.0.1, when starting without a Connection String, throws a ArgumentNullException.

OneTimeSetUp: SetUp : System.ArgumentNullException : Value cannot be null. (Parameter 'connectionString')
--SetUp
   at Microsoft.ApplicationInsights.Profiler.Shared.Services.ServiceProfilerContext..ctor(ConnectionString connectionString, IEndpointProvider endpointProvider, ILogger`1 logger)
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
   at System.Reflection.MethodBaseInvoker.InvokeDirectByRefWithFewArgs(Object obj, Span`1 copyOfArgs, BindingFlags invokeAttr)
   at System.Reflection.MethodBaseInvoker.InvokeWithFewArgs(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
...

This happens even if I have in my appsettings.json:

	"ServiceProfiler": {
		"IsDisabled": true
	},

In 2.7.3, it only used to log an error: Profiler Instrumentation Key is invalid.

This is quite annoying because during Development, I do not have a Connection String, nor do I want one.

[xiaomi7732]

@dstj Thanks for the feedback. This is an intentional change to

1. Share implementation / behavior of the OTel agent.
2. In an effort to deprecate the use of instrumentation key.

That said, it doesn't make sense to require it when profiler is disabled. I think that worth a bug fix.

As a work-around, please try set up a fake connection string. For example:

In appsettings.Development.json:

{
    "ApplicationInsights": {
        "ConnectionString": "InstrumenationKey=ccf1f02f-8f2a-4634-b20c-08ce23badeb3;IngestionEndpoint=https://westus3-1.in.applicationinsights.azure.com/"
    }
}

• The actual value isn't important, but you will at least have the instrumentation key section and the ingestion endpoint section in it.
• Be careful not to overwrite the actual connection string when deployed by accident.

I'll use this issue to track the actual fix to allow null connection string in case of profiler disabled.

[bifa-zuehlke]

Just checking in - do you know if this will be fixed soon? That way, we could skip this version and avoid setting up placeholder connection strings across all projects.

[xiaomi7732]

@bifa-zuehlke If you are okay with beta versions, the fix will be quick. If you will hold until the next stable version, it might take a couple of weeks.

[xiaomi7732]

I am sorry @bifa-zuehlke, I will be on vacation for a couple of weeks, and I didn't get a chance to look into fixing the issue. I'll work on that once getting back.