Phobos.Hosting 2.0.3-beta1

Akka.Hosting prototype support for Phobos.

Install-Package Phobos.Hosting -Version 2.0.3-beta1

dotnet add package Phobos.Hosting --version 2.0.3-beta1

<PackageReference Include="Phobos.Hosting" Version="2.0.3-beta1"/>

paket add Phobos.Hosting --version 2.0.3-beta1

Paket is a third-party, open source alternative to the NuGet client.

Release Notes

Phobos 2.x BETA Release** This is a BETA release of a new propsoed feature for Phobos 2.0 - "macro" tracing: the ability to disable automatic `akka.msg.recv` span creation but still receive the `SpanContext` from incoming messages and still propagate `SpanContext` to other actors via `TelemetrySpan` / `System.Diagnostic.Activity` instances you create yourself. Disabling Automatic Span Creation** You can disable automatic span creation for the entire `ActorSystem` via the following HOCON: ```hocon phobos.tracing.create-trace-upon-receive = off ``` We don't recommend doing this** as it's a potentially destructive action. Instead, it's better to disable automatic span creation in areas where you _know_ the system is busy. ```hocon akka.actor.deployment{ /manual1{ phobos.tracing.create-trace-upon-receive = off phobos.tracing.propagate-settings-to-children = on } } ``` This will allow you to disable automatic span creation for the entire hierarchy of actors beneath `/user/manual1`. You can also accomplish the same thing via C# or F# via the `Props` extension methods introduced by Phobos: ```csharp var myManualSpanActor = Sys.ActorOf(Props.Create(() => new ManualTraceCreator()) .WithInstrumentation( PhobosSettings.For(Sys).DefaultUserActorSettings .WithCreateTraceUponReceive(false) .WithPropagateToChildren(true)), "manual2"); ``` This will work identically to the HOCON above. When these settings are enabled, the affected actors will still have tracing enabled and will propagate any active trace data to other actors via `IActorRef.Tell` but _will not automatically create any additional `akka.msg.recv` spans on their own any longer_. Manually Creating Spans** So in order to create useful traces inside these areas, you can now access the `IPhobosActorContext.UsableContext` property - which contains a `SpanContext?` that can be used in the manual creation of OpenTelemetry spans: ```csharp public ManualTraceCreator() { Receive<GetActiveSpan>(_ => { // should be default(TelemetrySpan) when running with // phobos.tracing.create-trace-upon-receive = off Sender.Tell(new SpanResponse(Context.GetInstrumentation().ActiveSpan)); }); Receive<MyMsg>(m => { using (var mySpan = Context.GetInstrumentation().Tracer.StartActiveSpan("MyMsg", SpanKind.Consumer, Context.GetInstrumentation().UsableContext ?? default)) { _logging.Info("My event"); Sender.Tell(new MyReply("reply")); } }); } ``` This will allow the Phobos user full control over what appears in their spans and which actors / messages can produce spans. Span propagation still works automatically inside Phobos with automatic span creation disabled - but now you're responsible for creating your own spans. This should significantly reduce the amount of noise produced by the tracing system - we're going to experiment using this feature inside our [planned Akka.Streams support](https://github.com/petabridge/phobos-issues/issues/42).