Add NATS instrumentation

[AlixBa]

First, sorry for the review of 5000 rows, that's not very nice.

This PR aims at instrumenting NATS for both library and java agent, using the messaging conventions.

Few things:

• I left out JetStreams from the instrumentation for now (as I don't have a particular interest and I have never used)
• I didn't implement any messaging metrics. I'll take a look after this PR I think.
• I feel like the java agent advices are very verbose. If there is a better way of doing it, I'll gladly modify what I wrote.

[otelbot-java-instrumentation]

🔧 The result from spotlessApply was committed to the PR branch.

[AlixBa]

@laurit is it you I should ask a review from?

[laurit]

Currently there is a build failure, and a test failure.

[AlixBa]

not really sure about this, as I have to rely on a build. I think it would be better to let users do options.dispatcherFactory(...) as OpenTelemetryDispatcherFactory is now exposed

[AlixBa]

hey @laurit

could you have a second look at this one when you have the time?
Took all the comments and followed (I hope) a very close implementation from other messaging instrumentations.

muzzle passes locally and on previous builds, so I guess the error is transient.

[AlixBa]

might be worth checking if this needs to be applied before merging

[laurit]

one way we use for cleanup is

opentelemetry-java-instrumentation/instrumentation/apache-dubbo-2.7/testing/src/main/java/io/opentelemetry/instrumentation/apachedubbo/v2_7/AbstractDubboTest.java

Line 52 in 5b75b3f

@RegisterExtension static final AutoCleanupExtension cleanup = AutoCleanupExtension.create();

you can call cleanup.deferCleanup(...); immediately after you create whatever needs to be closed/cleaned and it will get executed after the test event when the test fails

[AlixBa]

deferCleanup requires AutoCloseable which is not the case for Dispatcher or Subscription.

Also this is to test properly this proxy

  // public void closeDispatcher(Dispatcher dispatcher)
  private Object closeDispatcher(Method method, Object[] args) throws Throwable {
    if (method.getParameterCount() == 1
        && args[0] instanceof Proxy
        && Proxy.getInvocationHandler(args[0]) instanceof OpenTelemetryDispatcher) {
      args[0] = ((OpenTelemetryDispatcher) Proxy.getInvocationHandler(args[0])).getDelegate();
    }

    return invokeMethod(method, delegate, args);
  }

Will the cleanup propagate the error to the test in case this is failing? Because this means that we didn't "unwrap" the otel wrapper, which would fail at runtime

[AlixBa]

as per the intended cleanup, it's declared in the abstract parent class

  @AfterAll
  static void afterAll() throws InterruptedException, TimeoutException {
    connection.drain(Duration.ZERO);
    natsContainer.close();
  }

[laurit]

You should assign message to the message return value otherwise this method will end up returning null which is not what it should be doing. You can verify this by modifying your test to assert on the return value of this method.

[AlixBa]

totally forgot to test the return type of the Request methods. Thanks for the reminder!

[AlixBa]

@laurit thanks a lot for your time on this

[otelbot]

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