HttpClient calls from .NET Framework not always auto wrapped

Describe the bug .NET Framework calls made using HttpClient are not automatically wrapped in a span within a ASP.NET Web API web app.

To Reproduce Steps to reproduce the behavior:

1. Clone this repo
2. Add a ASP.NET Web Application (.NET Framework) project to the sample folder (.NET 4.6.1). Select Web API template, uncheck configure for HTTPS.
3. Add the following existing projects as references: Elastic.AP, Elastic.Apm.AspNetFullFramework
4. Add to the <system.webserver> section in the Web.config:

<modules>
    <add name="ElasticApmModule" type="Elastic.Apm.AspNetFullFramework.ElasticApmModule, Elastic.Apm.AspNetFullFramework"/>
  </modules>

1. Edit Web.config to have a ElasticApm:ServerUrls appSetting pointing at your instance of APM server.
2. Edit ValuesController.Get() to contain:

// GET api/values
public IEnumerable<string> Get()
{
  var client = new HttpClient();
  var x = client.GetAsync("http://www.google.com").Result.Content.ReadAsStringAsync().Result;
  return new [] { $"Length: {x.Length}" };
}

1. Run service and send a request: GET /api/values

Expected behavior When the /api/values transaction is logged to the APM server, it should contain a span from the HttpClient call to google. A transaction for /api/values is logged just fine, it just has no spans.

I have only seen this work out of the box with the AspNetFullFrameworkSampleApp and haven’t been able to get it to work in any of my existing .Net framework services by just adding the module reference in the web.configs (in addition to installing the nuget packages). There is so much extra going on in AspNetFullFrameworkSampleApp that it is hard for me to compare what might be causing the issue.

I have put breakpoints on various methods in HttpDiagnosticListenerImplBase like OnNext, ProcessStartEvent, etc, with none getting hit.

The following breakpoints are hit while testing:

• ElasticApmModule.InitOnceForAllInstancesUnderLock (line 312)
• HttpDiagnosticListener.New (line 23)

I’m guessing I’m missing something simple. Please advise.

Thanks!

[sluebbert]

So you were right about version issues, but for me it was the System.Diagnostics.DiagnosticSource dll.

If I added System.Memory.dll, added binding redirects into my web.config for System.memory and System.Diagnostics.DiagnosticSource, and then swapped out the version of System.Diagnostics.DiagnosticSource from AspNetFullFrameworkSampleApp to my test app after building, it works!

I just need to figure out how to gracefully do that without my hackory.

It started working without adding System.Memory, it just threw exceptions complaining about it missing later on.

[vhatsura]

@gregkalapos, I did fast check, and yes it seems System.Diagnostics.DiagnosticSource of 4.0.0 version is enough for netstandard2.0 for getting event from HttpClient.