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https://issues.apache.org/jira/browse/NIFI-16454?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18127503#comment-18127503
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Divija Garg Ksolves Nifi Expertise commented on NIFI-16454:
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Hi Níno Martínez Wael ,
I would like to work on this issue. I have successfully reproduced it locally
and am currently reviewing the details. I will submit a pull request shortly.
Could you please assign this ticket to me?
Thanks!
> AllowListClassLoader throws and logs a NullPointerException for every class
> in the unnamed module
> -------------------------------------------------------------------------------------------------
>
> Key: NIFI-16454
> URL: https://issues.apache.org/jira/browse/NIFI-16454
> Project: Apache NiFi
> Issue Type: Bug
> Components: NiFi Stateless
> Affects Versions: 2.12.0
> Reporter: Níno Martínez Wael
> Priority: Major
>
> When NiFi Stateless is bootstrapped with a root class loader that sees
> classes from the classpath (the default StatelessBootstrap.bootstrap(config)
> uses the system class loader), every such class that is not in the allow-list
> goes through AllowListClassLoader.isClassAllowed. For a class in the unnamed
> module, Module.getName() returns null, and isModuleAllowed calls
> moduleName.startsWith(prefix) on it:
> {code}
> java.lang.NullPointerException: Cannot invoke "String.startsWith(String)"
> because "moduleName" is null
> at
> org.apache.nifi.stateless.bootstrap.AllowListClassLoader.isModuleAllowed(AllowListClassLoader.java:134)
> at
> org.apache.nifi.stateless.bootstrap.AllowListClassLoader.isClassAllowed(AllowListClassLoader.java:120)
> at
> org.apache.nifi.stateless.bootstrap.AllowListClassLoader.loadClass(AllowListClassLoader.java:71)
> ...
> at
> org.apache.nifi.stateless.config.PropertiesFileFlowDefinitionParser.<clinit>(PropertiesFileFlowDefinitionParser.java:73)
> ...
> at
> org.apache.nifi.stateless.bootstrap.StatelessBootstrap.parseDataflowDefinition(StatelessBootstrap.java:86)
> {code}
> The exception is caught and logged at DEBUG with the full stack trace
> ("Failed to determine if class ... is part of the implicitly allowed
> modules"), and the class is treated as not allowed. So the result is correct,
> but the log volume is not: running Stateless from a JUnit test with Logback
> and no configuration (root level DEBUG) produces one stack trace per
> classpath class, thousands for Jackson alone during
> PropertiesFileFlowDefinitionParser initialisation, which makes test runs look
> hung.
> *Steps to reproduce*
> # Put nifi-stateless-bootstrap 2.12.0 and its dependencies on a JUnit test
> classpath with logback-classic and no logback-test.xml.
> # Call StatelessBootstrap.bootstrap(config), then
> parseDataflowDefinition(...).
> # One DEBUG line plus a NullPointerException stack trace is logged for each
> classpath class, e.g. com.fasterxml.jackson.databind.ObjectMapper.
> *Expected*
> A class in the unnamed module is treated as "not in an allowed module"
> without an exception; at most a short DEBUG line is logged.
> *Suggested fix* (in isClassAllowed, before calling isModuleAllowed)
> {code:java}
> final String moduleName = (String) getName.invoke(module);
> if (moduleName == null) {
> return false; // unnamed module: classpath class, not implicitly allowed
> }
> {code}
> *Environment*
> NiFi Stateless 2.12.0, JDK 21, Maven Surefire 3.5.5, Logback 1.6.3.
> *Workarounds*
> * Set the logger org.apache.nifi.stateless to INFO or WARN.
> * Pass a root class loader to StatelessBootstrap.bootstrap(config,
> rootClassLoader) that only offers the allow-listed classes.
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