IllegalArgumentException while consuming an API in Micro Integrator

[ajit-pendse]

Description

New project is created with a simple Endpoint and API calling this endpoint, hosted on local Micro Integrator through Integration Studio.

While consuming API, client receives a HTTP 500 Error code with body as -

{
    "Fault": {
        "faultcode": "soapenv:Server",
        "faultstring": "Label cannot be null.",
        "detail": null
    }
}

In the server console, following stacktrace is printed -

ERROR {ServerWorker} - Error processing POST request for : /listing/create. java.lang.IllegalArgumentException: Label cannot be null.
	at io.prometheus.client.SimpleCollector.labels(SimpleCollector.java:68)
	at org.wso2.micro.integrator.observability.metric.handler.prometheus.reporter.PrometheusReporter.incrementCount(PrometheusReporter.java:204)
	at org.wso2.micro.integrator.observability.metric.handler.MetricHandler.incrementApiErrorCount(MetricHandler.java:290)
	at org.wso2.micro.integrator.observability.metric.handler.MetricHandler.handleError(MetricHandler.java:171)
	at org.apache.synapse.FaultHandler.executeExtendedSynapseHandlerOnFault(FaultHandler.java:166)
	at org.apache.synapse.FaultHandler.handleFault(FaultHandler.java:80)
	at org.apache.synapse.core.axis2.SynapseMessageReceiver.receive(SynapseMessageReceiver.java:107)
	at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:180)
	at org.apache.synapse.transport.passthru.ServerWorker.processNonEntityEnclosingRESTHandler(ServerWorker.java:401)
	at org.apache.synapse.transport.passthru.ServerWorker.processEntityEnclosingRequest(ServerWorker.java:460)
	at org.apache.synapse.transport.passthru.ServerWorker.run(ServerWorker.java:208)
	at org.apache.axis2.transport.base.threads.NativeWorkerPool$1.run(NativeWorkerPool.java:172)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.lang.Thread.run(Thread.java:840)

Steps to Reproduce

1. Open Integration Studio
2. Create a new project containing docker exporter and kubernetes exporter (apart from composite exporters and Configs projects)
3. Create a new Endpoint pointing to any external backend
4. Create an API calling this endpoint and exposing a route
5. Call the exposed route of API from a client like Postman

Version

4.3.0

Environment Details (with versions)

OS - Mac OS Sequoia 15.1
Integration Studio - 8.3.0
Java/JRE -
openjdk version "17.0.13" 2024-10-15
OpenJDK Runtime Environment Homebrew (build 17.0.13+0)
OpenJDK 64-Bit Server VM Homebrew (build 17.0.13+0, mixed mode, sharing)