HttpListenerPrefixes other than localhost

[GuglielmoFrigerio]

Does anyone tried to configure the exporter to publish on every network interface the host provide?
I've tried the following prefixes

• http://0.0.0.0:9184
• http://+:9184
• http://*:9184
• http://{an-existing-network-interface-ip}:9184

Nothing seems to work.

I've tried under Windows 11 & DotNet 6.

I wanted to test a scenario where the Prometheus server is remote respect to the application.

[Yun-Ting]

Hi @GuglielmoFrigerio,
Could you share the code on how you configure the Prometheus server please?
Thank you.

[sakowiczm]

Guys, I think I have exactly the same problem. I'm using examples\Console\TestPrometheusExporter.cs and if I modify HttpListenerPrefixes collection to use anything different than localhost - I'm not able to access /metrics endpoint. Examples:

This works fine:

  options.HttpListenerPrefixes = new string[] {
      "http://localhost:9184"
  };

and below ones does not:

  options.HttpListenerPrefixes = new string[] {
      "http://*:9184", "http://+:9185"
  };

  options.HttpListenerPrefixes = new string[] {
      "http://{host-ip}:9184"
  };

I'm trying to expose /metrics using host IP so it can be reached by Prometheus running in a docker container.
I've disabled the firewall for the test duration - just in case.
Any idea what I may be doing wrong here?

Thanks.

[GuglielmoFrigerio]

Hi @Yun-Ting this is how I configure Prometheus in the Startup.cs:

        var prometheusConfigSection = Configuration.GetSection("Prometheus");
        var prefixes = prometheusConfigSection.GetSection("prefixes").Get<string[]>();
        _meterProvider = Sdk.CreateMeterProviderBuilder()
            .AddMeter("SessionControl")
            .AddPrometheusExporter(opt =>
            {
                opt.StartHttpListener = true;
                opt.HttpListenerPrefixes = prefixes;
            })
            .Build();

This is the app settings:

 "Prometheus": {
   "prefixes": [
     "http://localhost:9174/"
   ]
 }

[8]

Hi,

I stumbled over the same bug, which makes exposing the metrics interface on all interfaces impossible.

After taking a look at the source code, I came up with the following workaround until the bug is fixed, by setting the private backing field directly using reflection, thereby sidestepping the buggy validation:

...
.AddPrometheusExporter(options =>
    {
      options.StartHttpListener = true;

      options.GetType()
        ?.GetField("httpListenerPrefixes", BindingFlags.NonPublic | BindingFlags.Instance)
        ?.SetValue(options, new[] { "http://*:9464" });
    });

Take care,
Martin