Utilize AgentListener inside agent extension

[Cavvar]

Hello everyone!

I was wondering if it is somehow possible to add an AgentListener to an agent extension.

The listener is implemented as follows:

import com.google.auto.service.AutoService;
import io.opentelemetry.instrumentation.api.config.Config;
import io.opentelemetry.javaagent.extension.AgentListener;

@AutoService(AgentListener.class)
public class CustomAgentListener implements AgentListener {

    @Override
    public void beforeAgent(Config config) {
        System.out.println("Hello There;)");
    }
}

The java agent is configured like this (Dockerfile.jvm from a Quarkus application):

ENV JAVA_OPTIONS="-javaagent:/agents/opentelemetry-javaagent-all.jar \
                  -Dotel.traces.exporter=jaeger \
                  -Dotel.exporter.jaeger.endpoint=http://jaeger:14250 \
                  -Dotel.metrics.exporter=none \
                  -Dotel.javaagent.extensions=/agents/custom-agent-extension-0.0.1.jar \
                  -Dquarkus.http.host=0.0.0.0 -Djava.util.logging.manager=org.jboss.logmanager.LogManager"

Additionally, I am using a custom SpanProcessor and SpanExporter which are configured through the SdkTracerProviderConfigurer interface.

import com.google.auto.service.AutoService;
import io.opentelemetry.exporter.jaeger.JaegerGrpcSpanExporter;
import io.opentelemetry.javaagent.extension.AgentListener;
import io.opentelemetry.sdk.autoconfigure.spi.SdkTracerProviderConfigurer;
import io.opentelemetry.sdk.trace.SdkTracerProviderBuilder;
import java.util.ServiceLoader;

@AutoService(SdkTracerProviderConfigurer.class)
public class CustomSdkTracerConfigurer implements SdkTracerProviderConfigurer {

    @Override
    public void configure(SdkTracerProviderBuilder sdkTracerProviderBuilder) {
        sdkTracerProviderBuilder.addSpanProcessor(new CustomSpanProcessor(new CustomSpanExporter, true));
    }
}

As of right now, the message from the beforeAgent hook is NOT visible. Am I missing something?

Thanks for any help!

[mateuszrzeszutek]

Hey @Cavvar ,
We've recently had this issue #4049 that broke javaagent SPIs in extensions. Could you check whether there's a similar exception in your applications logs? (Might need the -Dotel.javaagent.debug=true property set for extensive logging)
The issue I linked is already fixed and will be shipped in 1.6.0 by the way.

[trask]

hey @Cavvar, I think you will run into #4049, but since you aren't getting that exception I wonder if you are running into something else first. you can try with the latest snapshot to eliminate #4049 as the issue. if your AgentListener is still not being called, can you publish a small repro of your extension that we can look at?

[Cavvar]

Hello @trask. I used the snapshot and was able to see the logging message from inside the beforeAgent hook. Thanks for the help!

[Yahire3388]

Hi @Cavvar , @trask

can you share the snapshot again? it is not available at the link.

Thanks

[mateuszrzeszutek]

Try the 1.13.0-SNAPSHOT

[Yahire3388]

Hi @mateuszrzeszutek @trask
Tried, but it doesn't seem to add any custom traces. I am trying to export the traces directly to database by adding Mongo db connection code in agent extension from Span processor or by span exporter class.

Thanks