Enable using JMX Metrics instrumation as a library, not only through javaagent

[adamw]

Is your feature request related to a problem? Please describe.

I'd like to use the Otel <-> JMX integration as a library, without the need to install a Java Agent, as described currently on: https://github.com/open-telemetry/opentelemetry-java-instrumentation/blob/main/instrumentation/jmx-metrics/javaagent/README.md

I don't think the javaagent code is published, I've been only able to find the library on Maven Central:

<dependency>
    <groupId>io.opentelemetry.instrumentation</groupId>
    <artifactId>opentelemetry-jmx-metrics</artifactId>
    <version>2.8.0-alpha</version>
    <scope>runtime</scope>
</dependency>

Describe the solution you'd like

My goal is to include all observability-related setup as code, in the main method of the application. I've got OTEL working without problems using AutoConfiguredOpenTelemetrySdk.initialize().getOpenTelemetrySdk(), but to get the JMX integration I think I'll have to copy the initialisation code from JmxMetricInsightInstaller.java for now.

Ideally. I'd be able to do sth like JmxMetrics.initialise(openTelemetry), given an instance of OpenTelemetry.

Describe alternatives you've considered

No response

Additional context

No response

[trask]

hi @adamw!

<dependency>
    <groupId>io.opentelemetry.instrumentation</groupId>
    <artifactId>opentelemetry-jmx-metrics</artifactId>
    <version>2.8.0-alpha</version>
    <scope>runtime</scope>
</dependency>

I think this is what you want.

Ideally. I'd be able to do sth like JmxMetrics.initialise(openTelemetry), given an instance of OpenTelemetry.

check out

opentelemetry-java-instrumentation/instrumentation/jmx-metrics/library/src/main/java/io/opentelemetry/instrumentation/jmx/engine/JmxMetricInsight.java

Line 27 in faff2d9

public static JmxMetricInsight createService(OpenTelemetry ot, long discoveryDelay) {

[adamw]

@trask Thanks, I do have that, and I'm calling JmxMetricInsight.createService. However, I had to copy the code which calls .start on the created instance with the proper configuration. The JmxMetricInsightInstaller.java does exactly that: reads configuration and calls JmxMetricInsight.createService. I suppose the configuration parsing/reading class could also be part of a published jar, so that it would be usable in a no-agent setup?

[adamw]

In my case, the proper way to solve my problem (exposing runtime JVM metrics) was to use a dedicated library: opentelemetry-runtime-telemetry-java8, instead of using the JMX metrics (see #12310).

However, I still think that having a way of using the JMX metrics bridge without the java agent would be beneficial, so I'm keeping this open.

[trask]

@trask Thanks, I do have that, and I'm calling JmxMetricInsight.createService. However, I had to copy the code which calls .start on the created instance with the proper configuration. The JmxMetricInsightInstaller.java does exactly that: reads configuration and calls JmxMetricInsight.createService. I suppose the configuration parsing/reading class could also be part of a published jar, so that it would be usable in a no-agent setup?

cc @PeterF778

[PeterF778]

If I remember correctly, JMX Metric Insight uses two different calls for building the configuration (parser) and for starting the collection to make sure that no attempts to report metrics happen before the agent is fully initialized (metric exporter, etc.). I'll have another look to see if this can be made more user friendly.

[PeterF778]

I revisited the code. The opentelemetry-jmx-metrics.jar contains both the yaml parser and instrumentation. However, the default configuration files for supported platforms, as well as the controlling properties otel.jmx.target.system, otel.jmx.config (and others), are Java Agent specific. Hence, JmxMetricInsightInstaller uses two steps: it creates a MetricConfiguration and creates a service instance, passing the configuration as well.
It is easy to introduce a new entry createAndStartService(OpenTelemetry otel, MetricConfiguration conf), but I do not think it will make a big difference.