kamon-io/kamon-http4s

Kamon Integration for http4s

Kamon.io

Sources for the Kamon website.

Development

For installing requirements, read the Jekyll Docs.

To start the local server, run:

$ bundle install
$ bundle exec jekyll serve --livereload

• by default, local server will be listening on port 4000.
• bundle exec restricts the Ruby environment to only use gems set in the project's Gemfile.

For updating gem versions, run:

$ bundle update

kamon-http4s's Issues

The X-B3-* Headers are not properly propagated when run the client inside a service

• The kamon context is lost because Kamon.withContext(..) is executed eagerly instead of inside of a delay

Thanks @aggenebbisj for report this.

Kamon looses context when http4s client raises an exception

If the http4s client raises an exception - e.g. when e.g. java.util.concurrent.TimeoutException is raised after setting connection timeout:

BlazeClientBuilder[F]
      .withRequestTimeout(100.millis)

then it seems that kamon context is lost, and e.g. traceId is not propagated to MDC for logging.

If there is not any exception but a request ending with e.g. 500, then it seems to be working fine.

Question about http4s 0.18.x support

The README says this update is "soon". We are building a new app using 0.18.x and we would like to provide Prometheus metrics from the service. Can you give us any idea when this update might be available? Thanks.

Scala 2.13 support

Please update to have Scala 2.13 support

Kamon 2.0 support

Hey!

Is there any ETA on when kamon 2.0 will be supported in this module?

Update kamon-core

This project still depends on kamon-core 2.2.x. Can this be updated?

And in general @ivantopo - why is this not in kamon core repository like the rest of instrumentation? Should we consider this module as not maintained anymore?

Spans get mixed up

TL;DR calling an endpoint multiple times often causes the underlying spans to end up in a single trace.

Interesting parts:

• it didn't happen (for me) when no DB calls were made (but it didn't happen with the DB calls when the server was akka-http, not http4s)
• it's happening regardless of whether the effect is IO or Task

Discussion on gitter: https://gitter.im/kamon-io/Kamon?at=5af7460ee0b50c2d05b9248b

Reproduction repo & steps: https://github.com/kubukoz/kamon-repro

The Context Headers are not properly propagated

• The kamon context is always overridden because we are created each time a new context

this line:

scope <- F.delay(Kamon.storeContext(Context.create(Span.ContextKey, serverSpan)))

should be replaced by:

scope <- F.delay(Kamon.storeContext(incomingContext.withKey(Span.ContextKey, serverSpan)))

Release 1.0.12 with http4s 0.20.0 support

http4s was updated to 0.20.0 in #22 but this doesn't yet seem to have been released.

Thanks! :)

Release of 2.0.3

The current documentation doesn't reflect released versions.

Is it possible to release the version 2.1.0? If not, then I can fix the documentation.

Properly finish the current span when an error occurs in a request

Memory leak in span_processing_xxx metrics

• http4s version 0.20.x
• kamon http4s version 1.0.11

We noticed a memory leak in span_processing_time_seconds_xxx metrics in the field "parent"

Kamon context is not available to http4s logging middleware

The kamon context is not available to the http4s logging middleware. This can be seen by configuring logback to record the trace ID. There is a minimal reproduction at https://github.com/dangerousben/http4s-kamon-demo.

2021-01-20 08:32:39,752 [ioapp-compute-1] [2906519629fe1015] INFO Main$ In service
2021-01-20 08:32:39,945 [ioapp-compute-7] [undefined] INFO o.h.server.middleware.Logger HTTP/1.1 GET / Headers(Host: localhost:8080, User-Agent: HTTPie/1.0.3, Accept-Encoding: gzip, deflate, Accept: */*, Connection: keep-alive) body=""
2021-01-20 08:32:39,954 [ioapp-compute-6] [undefined] INFO o.h.server.middleware.Logger HTTP/1.1 200 OK Headers() body=""

The first log statement, within the service, includes the trace ID, but the following two from middleware.Logger do not.

Dynamic values in paths are not replaced with placeholders

Hi and thank you for this library!
I'm in the progress of migrating an application from akka-http to http4s and I noticed a behavioral difference.
While in akka-http paths are reported to Prometheus with a {} placeholder when the segment contains dynamic values (like integers), in http4s paths are reported literally:
For example:

with http4s:

/v1/organization/30755/authors/suggested

with akka-http:

/v1/organization/{}/authors/suggested

Is this intended? Can I configure Kamon to have the same behavior? In case it's a missing feature, are you willing to merge a PR implementing the change (maybe guiding me to show what needs to be changed)

Thank you!
Lorenzo

Blaze client loses context in callback

Hi!

I'm playing with kamon-http4s again and I'm trying to wrap the blaze client with the middleware. Unfortunately, my context gets lost at the point Blaze creates a connection. I tracked it down to here:

//ClientChannelFactory.scala, blaze-core 0.14.11
  def connect(
      remoteAddress: SocketAddress,
      bufferSize: Int = bufferSize): Future[HeadStage[ByteBuffer]] = {
    val p = Promise[HeadStage[ByteBuffer]]

    try {
      val ch = AsynchronousSocketChannel.open(group.orNull)

      val onTimeout = //...

      val scheduledTimeout = scheduler.schedule(onTimeout, connectTimeout)

      val completionHandler = new CompletionHandler[Void, Null] {
        //...

        def completed(result: Void, attachment: Null): Unit = {
          channelOptions.applyToChannel(ch)
          p.trySuccess(new ByteBufferHead(ch, bufferSize = bufferSize))
          scheduledTimeout.cancel()
        }
      }

      try {
        ch.connect(remoteAddress, null: Null, completionHandler)
      } catch {
         //...
      }
    } catch { case NonFatal(t) => p.tryFailure(t) }

    p.future
  }

As far as I understand, the context should somehow be passed to the completion handler at instantiation time and restored in def completed, before completing the promise (then the further transformations on the future would also have the context, which they don't - so even though all the tracing information is in the request thanks to the middleware, the Kamon context has no span after any client call).

Can this be done somehow through the configuration of the agent, or would it require special treatment in blaze (e.g. being able to inject a method that creates the completion handler)?

Add support for Cats Effect 3

Please add new version with Cats Effect 3 support. There is ready to merge PR #45

Remove global mutable state in NameGenerator

Examples on README

Hello,

We're trying to get kamon-http4s to work in our project. But, the README in the repository is 1.5 year old and having trouble following the example in there.

Would like to ask if the project is still maintained and is there an example we could follow to integrate with kamon-http4s?

Following the example in the current README, we are trying to figure out:

1. Where does Effect get imported from?
2. How to configure a BlazeBuilder[F] with the latest versions of the module?(https://github.com/http4s/blaze#http4s-backend)