OpenTelemetry exporters documentation improvements

[brunobat]

• Fixes: "Provider io.opentelemetry.exporter.otlp.internal.OtlpSpanExporterProvider not found" #48438
• Fixes: Quarkus fails to start up if I set quarkus.otel.traces.exporter=otlp #48570

[geoand]

If the value is not supported, we should update the config to indicate that and also provide a good error message

[github-actions]

🙈 The PR is closed and the preview is expired.

[spio]

Hi, Bruno.

It seems good to me.

I would suggest some more changes to the docs:

• In the description of the "quarkus.otel.traces.exporter" property (under both titles "OpenTelemetry Configuration Reference" and "Disable all or parts of the OpenTelemetry extension"), I think that the "otlp" option shoud be removed as a valid value, because it is not.
• By removing that value, the new section "The OpenTelemetry OTLP exporter" it's not necessary; in fact, it seems too severe to me to say "This is currently not supported in quarkus"; perhaps stating that "this is used by default in Quarkus" instead of that sentence is a little more polite.
• I think that adding a quick link to database tracing there could be useful.

And one last thing, but it is not fully related to this: it seems strange to me that, by default, direct jdbc connections are not traced by default (i.e. quarkus.datasource.jdbc.telemetry=false), but reactive connections are (quarkus.otel.instrument.vertx-sql-client=true). By the way, if you can, I would suggest to also modify the Quarkus Datasource config docs (https://es.quarkus.io/guides/datasource) to show, under the "Datasource tracing" title, that each datasource can be configured using "quarkus.datasource..jdbc.telemetry=true", as it is shown under "Datasource health check", "Datasource metrics" and "Narayana transaction manager integration".

Regards.

[gsmet]

I added a few suggestions.

I agree with @geoand that we should improve the error we get.

The current error (coming from the issue):

Caused by: java.lang.ClassNotFoundException: okhttp3.Callback
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526)
	at io.quarkus.bootstrap.classloading.QuarkusClassLoader.loadClass(QuarkusClassLoader.java:576)
	at io.quarkus.bootstrap.classloading.QuarkusClassLoader.loadClass(QuarkusClassLoader.java:523)

Given we are not supposed to use Okhttp at all, this is extremely puzzling and I don't think adding some doc is enough. The additional doc is highly welcome though :)

[geoand]

@brunobat do you plan to update the PR as per the recommendations? Asking because the current state is less than optimal

[spio]

I added a few suggestions.

I agree with @geoand that we should improve the error we get.

The current error (coming from the issue):

Caused by: java.lang.ClassNotFoundException: okhttp3.Callback
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526)
	at io.quarkus.bootstrap.classloading.QuarkusClassLoader.loadClass(QuarkusClassLoader.java:576)
	at io.quarkus.bootstrap.classloading.QuarkusClassLoader.loadClass(QuarkusClassLoader.java:523)

Given we are not supposed to use Okhttp at all, this is extremely puzzling and I don't think adding some doc is enough. The additional doc is highly welcome though :)

@gsmet , this error occurs because of a combination of factors that should be resolved with the corrections in the docs made by @brunobat; in fact, it is an unhappy combination of factors:
1 - io.opentelemetry:opentelemetry-exporter-otlp uses OKHttp3. But Quarkus OpenTelemetry does not really need that. So, the problem should not arise in first place if a project does not include that dependency.
2 - Quarkus 3.20 OpenTelemetry has a dependency (although it is not used) on io.opentelemetry:opentelemetry-exporter-otlp:1.44.0, which in turn depends on an old version of OKHttp3, which has a bug (precisely, the class okhttp3.Callback is missing). But, if you, in a project, do not set otlp as an exporter, the problem won't arise either, because it will not try to use that class.
3 - If you, in a project, override the io.opentelemetry:opentelemetry-exporter-otlp version with 1.44.1, the ClassNotFoundException disapears, because it depends on a newer version of OkHttp3. But, as I understand, you should not include a dependency on io.opentelemetry : opentelemetry-exporter-otlp in a Quarkus Project (again, Quarkus 3.20 Telemetry has a dependency on it, but if you do not set otlp as an exporter, which is now un-documented, then that should not be a problem).

[brunobat]

This is on hold due to other ongoing work.

[brunobat]

Dependency removed and error message thown on build.

[geoand]

I added a minor comment. I would also like to have @gsmet's suggestions applied

[brunobat]

It should be better now, @geoand

[quarkus-bot]

Status for workflow Quarkus Documentation CI

This is the status report for running Quarkus Documentation CI on commit 828775b.

✅ The latest workflow run for the pull request has completed successfully.

It should be safe to merge provided you have a look at the other checks in the summary.

Warning

There are other workflow runs running, you probably need to wait for their status before merging.

[quarkus-bot]

Status for workflow Quarkus CI

This is the status report for running Quarkus CI on commit 828775b.

✅ The latest workflow run for the pull request has completed successfully.

It should be safe to merge provided you have a look at the other checks in the summary.

You can consult the Develocity build scans.

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Flaky tests - Develocity

⚙️ JVM Integration Tests - JDK 17

📦 integration-tests/kafka-devservices

✖ io.quarkus.it.kafka.continuoustesting.DevServicesDevModeTest.testDevModeServiceDoesNotRestartContainersOnCodeChange - History

• expected: <false> but was: <true> - org.opentest4j.AssertionFailedError

org.opentest4j.AssertionFailedError: expected: <false> but was: <true>
	at org.junit.jupiter.api.AssertionFailureBuilder.build(AssertionFailureBuilder.java:151)
	at org.junit.jupiter.api.AssertionFailureBuilder.buildAndThrow(AssertionFailureBuilder.java:132)
	at org.junit.jupiter.api.AssertFalse.failNotFalse(AssertFalse.java:63)
	at org.junit.jupiter.api.AssertFalse.assertFalse(AssertFalse.java:36)
	at org.junit.jupiter.api.AssertFalse.assertFalse(AssertFalse.java:31)
	at org.junit.jupiter.api.Assertions.assertFalse(Assertions.java:231)
	at io.quarkus.it.kafka.continuoustesting.DevServicesDevModeTest.testDevModeServiceDoesNotRestartContainersOnCodeChange(DevServicesDevModeTest.java:81)

---

⚙️ JVM Integration Tests - JDK 21

📦 integration-tests/kafka-devservices

✖ io.quarkus.it.kafka.continuoustesting.DevServicesDevModeTest.testDevModeServiceDoesNotRestartContainersOnCodeChange - History

• expected: <false> but was: <true> - org.opentest4j.AssertionFailedError

org.opentest4j.AssertionFailedError: expected: <false> but was: <true>
	at org.junit.jupiter.api.AssertionFailureBuilder.build(AssertionFailureBuilder.java:151)
	at org.junit.jupiter.api.AssertionFailureBuilder.buildAndThrow(AssertionFailureBuilder.java:132)
	at org.junit.jupiter.api.AssertFalse.failNotFalse(AssertFalse.java:63)
	at org.junit.jupiter.api.AssertFalse.assertFalse(AssertFalse.java:36)
	at org.junit.jupiter.api.AssertFalse.assertFalse(AssertFalse.java:31)
	at org.junit.jupiter.api.Assertions.assertFalse(Assertions.java:231)
	at io.quarkus.it.kafka.continuoustesting.DevServicesDevModeTest.testDevModeServiceDoesNotRestartContainersOnCodeChange(DevServicesDevModeTest.java:81)