How do I add a custom ConfigurableSamplerProvider?

[stnor]

Hi,
I want to write my own Sampler, and want to get started with a "Hello" sampler provider:

-Dotel.traces.sampler=hello

public class HelloSamplerProvider implements ConfigurableSamplerProvider {

    @Override
    public Sampler createSampler(ConfigProperties config) {
        System.out.println("****** HELLO SAMPLER CREATED ********");
        return new RateLimitingSampler(1);
    }

    @Override
    public String getName() {
        return "hello";
    }
}

I have tried putting this class within my app, in a custom otel javaagent and as a separate jar with -Dotel.javaagent.experimental.extensions=/path/to/my/sampler.jar

Nothing seems to be working for me. Any ideas? Pointers to docs?

ERROR io.opentelemetry.javaagent.OpenTelemetryAgent
java.lang.reflect.InvocationTargetException
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:564)
	at io.opentelemetry.javaagent.OpenTelemetryAgent.agentmain(OpenTelemetryAgent.java:64)
	at software.amazon.opentelemetry.javaagent.bootstrap.AwsAgentBootstrap.agentmain(AwsAgentBootstrap.java:28)
	at software.amazon.opentelemetry.javaagent.bootstrap.AwsAgentBootstrap.premain(AwsAgentBootstrap.java:24)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:564)
	at java.instrument/sun.instrument.InstrumentationImpl.loadClassAndStartAgent(InstrumentationImpl.java:513)
	at java.instrument/sun.instrument.InstrumentationImpl.loadClassAndCallPremain(InstrumentationImpl.java:525)
Caused by: java.lang.reflect.InvocationTargetException
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:564)
	at io.opentelemetry.javaagent.bootstrap.AgentInitializer.startAgent(AgentInitializer.java:44)
	at io.opentelemetry.javaagent.bootstrap.AgentInitializer.initialize(AgentInitializer.java:30)
	... 13 more
Caused by: io.opentelemetry.sdk.autoconfigure.ConfigurationException: Unrecognized value for otel.traces.sampler: hello

[trask]

hey @stnor!

The way this is supported today is by building a custom distro of the the java agent:

• https://github.com/open-telemetry/opentelemetry-java-instrumentation/tree/main/examples/distro
• https://github.com/open-telemetry/opentelemetry-java-instrumentation/blob/main/examples/distro/custom/src/main/java/com/example/javaagent/DemoSampler.java

Or through an unsupported/undocumented feature: otel.initializer.jar

Both of these are painful, and we are working on making it simpler, supported, and documented:

• Consolidate otel.exporter.jar and otel.initializer.jar into single feature otel.javaagent.extensions? #2442
• First POC for external extension loading #2881

[stnor]

Thanks. My issue w the agent approach was that I was missing the META-INF/services/io.opentelemetry.sdk.autoconfigure.spi.ConfigurableSamplerProvider configuration