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Opentelemetry build

This project provides an API for instrumenting server software using opentelemetry, as well as connectors to talk to opentelemetry software such as jaeger.

License

MIT

Features

Use

For now, instrument traces/spans, logs, and metrics manually:

module Otel = Opentelemetry
let (let@) f x = f x

let foo () =
  let@ scope = Otel.Trace.with_  "foo"
      ~attrs:["hello", `String "world"] in
  do_work();
  Otel.Metrics.(
    emit [
      gauge ~name:"foo.x" [int 42];
    ]);
  do_more_work();
  ()

Setup

If you're writing a top-level application, you need to perform some initial configuration.

  1. Set the service_name;
  2. optionally configure [ambient-context][] with the appropriate storage for your environment — TLS, Lwt, Eio…;
  3. and install a Collector (usually by calling your collector's with_setup function.)

For example, if your application is using Lwt, and you're using ocurl as your collector, you might do something like this:

let main () =
  Otel.Globals.service_name := "my_service";
  Otel.GC_metrics.basic_setup();

  Opentelemetry_ambient_context.set_storage_provider (Opentelemetry_ambient_context_lwt.storage ());
  Opentelemetry_client_ocurl.with_setup () @@ fun () ->
  (* … *)
  foo ();
  (* … *)

[ambient-context]: now vendored as opentelemetry.ambient-context, formerly https://v3.ocaml.org/p/ambient-context

Configuration

The library is configurable via Opentelemetry.Config, via the standard opentelemetry env variables, or with some custom environment variables.

Collector opentelemetry-client-ocurl

This is a synchronous collector that uses the http+protobuf format to send signals (metrics, traces, logs) to some other collector (eg. otelcol or the datadog agent).

Do note that this backend uses a thread pool and is incompatible with uses of fork on some Unixy systems. See #68 for a possible workaround.

Collector opentelemetry-client-cohttp-lwt

This is a Lwt-friendly collector that uses cohttp to send signals to some other collector (e.g. otelcol). It must be run inside a Lwt_main.run scope.

Opentelemetry-trace

The optional library opentelemetry.trace, present if trace is installed, provides a collector for trace. This collector forwards and translates events from trace into opentelemetry. It's only useful if there also is also a OTEL collector.

License

MIT

Semantic Conventions

Not supported yet.