Doc for Jaeger tracing integration in 3.x: shows incorrect port as of Helidon 3.0 and maybe should discuss removed config settings

[tjquinno]

Environment Details

• Helidon Version: 3.x, (4.x?)
• Helidon SE or Helidon MP SE and MP
• JDK version:
• OS:
• Docker version (if applicable):

---

Problem Description

1. Helidon 3.x uses the Jaeger OpenTelemetry client to send information to the Jaeger server. That client uses port 14250 (correctly defaulted in the JaegerTracerBuilder class.

   But our doc for Jaeger tracing integration uses port 14240, not 14250 (or leaving it unset to use the correct default). See the config example snippets just below the config tables at https://helidon.io/docs/v3/#/se/tracing#_configuration_options_3 and https://helidon.io/docs/v3/#/mp/tracing#_configuration_options_3.

   We could simply remove the port setting. The default in the code works correctly and the config doc shows port as a config key so readers will know they can override the default if they need to.

2. Several config keys that we supported in 2.x we no longer support because 3.x uses the OpenTelemetry tracing client rather than the native Jaeger one (as 2.x did). Should the doc contain a brief note at least listing these and/or explaining workarounds if any? For example, propagation is no longer supported, but propagation: b3 is no longer needed because the Helidon's JaegerTracerBuilder class always includes the OpenTelemetry B3Propagator.

   The class-level JavaDoc for JaegerTracerBuilder has changed accordingly, but we mention nothing in the doc on our website. See the JaegerTracerBuilder source diffs to see which keys are no longer supported. Here is a copy of the config code that shows which keys were supported in 2.x but not in 3.x:

        config.get("token").asString().ifPresent(this::token);
        config.get("username").asString().ifPresent(this::username);
        config.get("password").asString().ifPresent(this::password);
        config.get("propagation").asList(String.class).ifPresent(propagations -> {
            propagations.stream()
                    .map(String::toUpperCase)
                    .map(Configuration.Propagation::valueOf)
                    .forEach(this::addPropagation);
   
        });
        config.get("log-spans").asBoolean().ifPresent(this::logSpans);
        config.get("max-queue-size").asInt().ifPresent(this::maxQueueSize);
        config.get("flush-interval-ms").asLong().ifPresent(this::flushIntervalMs);
   ...
        config.get("sampler-manager").asString().ifPresent(this::samplerManager);
   

Steps to reproduce

• Enhance the MP QuickStart example by adding the following to microprofile-config.properties: (this came from a user for whom this set-up worked correctly in Helidon 2.x)

  tracing.service=s1-auth-svc
  tracing.protocol=http
  tracing.host=localhost
  tracing.port=14240
  tracing.sampler-type=const
  tracing.sampler-param=1
  tracing.components.security.enabled=false
  tracing.paths.1.path=/metrics
  tracing.paths.1.enabled=false
  tracing.paths.2.path=/health
  tracing.paths.2.enbled=false
  

• Start Jaeger (make sure its log reports it is listening on 14250).

• Build and run the modified MP QuickStart app.

• curl http://localhost:8080/greet

• The QuickStart output shows a failure to report the tracing data.

[ljamen]

Fixed by #6113