NULL check missing in agent instrumentation code

[debugthings]

When the agent attempts to view the existing correlation headers it does not perform a NULL check here.

This can throw an exception during the filter pipeline and lead to an internal server error.

It is recommended that we add a check similar to this one to avoid a nullref exception.

It was see recently on a struts application using thew new 2.0.0-BETA SDK and form based security with j_security_check.

[nicolehaugen]

I have also hit this issue. Here are the repro steps:

1.) Follow these steps to setup AI for dependencies: https://docs.microsoft.com/en-us/azure/application-insights/app-insights-java-agent

2.) Use the ToDo List sample app which is a Java SpringBoot app that uses the Azure Document DB library and App Insights library. Specifically, fork the code in the ai branch: https://github.com/Microsoft/todo-app-java-on-azure/tree/ai.

3.) Follow the ReadMe's steps to build and run the app (as shown here: https://github.com/Microsoft/todo-app-java-on-azure). When attempting to run the app, you'll get the following exception:

Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.microsoft.azure.documentdb.DocumentClient]: Factory method 'documentClient' threw exception; nested exception is java.lang.NullPointerException
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:189) ~[spring-beans-4.3.12.RELEASE.jar!/:4.3.12.RELEASE]
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:588) ~[spring-beans-4.3.12.RELEASE.jar!/:4.3.12.RELEASE]
... 88 common frames omitted
Caused by: java.lang.NullPointerException: null
at com.microsoft.applicationinsights.web.internal.correlation.TelemetryCorrelationUtils.retrieveCorrelationContext(TelemetryCorrelationUtils.java:140) ~[applicationinsights-web-2.0.0-BETA.jar!/:na

[grlima]

@nicolehaugen79 - is it possible you have not configured the necessary Beans to have the AppInsights filter properly configured. We were able to repro this issue when the filter was not properly configured in Spring Boot. See step 4 of this guide on how to configure AppInsights Filter in spring boot: https://github.com/AzureCAT-GSI/DevCamp/tree/master/HOL/java/06-appinsights

[grlima]

Closing issue as the fix has been merged. #541