[NIFI-6874] nifi-nar-maven-plugin "Could not generate extensions' documentation" with native libraries

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: nifi-nar-maven-plugin-1.3.1
• Component/s: Extensions, Tools and Build
• Assignee: Unassigned
• Reporter: Peter Radden
• Created: 15/Nov/19 16:40
• Updated: 22/Jul/20 09:12

Description

org.apache.maven.plugin.MojoExecutionException: Failed to create Extension Documentation
    at org.apache.nifi.NarMojo.generateDocumentation (NarMojo.java:596)
    at org.apache.nifi.NarMojo.execute (NarMojo.java:499)
    ...
Caused by: java.lang.UnsatisfiedLinkError: no [Library] in java.library.path
    at java.lang.ClassLoader.loadLibrary (ClassLoader.java:1867)
    at java.lang.Runtime.loadLibrary0 (Runtime.java:870)
    at java.lang.System.loadLibrary (System.java:1122)
    ...
    at org.apache.nifi.processor.AbstractSessionFactoryProcessor.initialize (AbstractSessionFactoryProcessor.java:63)
    at org.apache.nifi.documentation.AbstractDocumentationWriter.initialize (AbstractDocumentationWriter.java:86)

Custom processors that require native libraries for the implementation fail to generate documentation during nar build due to the need to initialize the processor.

While this could be resolved by a command line update to the java.library.path, I think that it would be better to extend the ExtensionClassLoader to attempt to find the libraries (similar to as done by the NarClassLoader.

My current temporary solution which uses a customized nifi-nar-maven-plugin is to add the following function to the ExtensionClassLoader:

protected String findLibrary(final String libname)
{
    final File nativeDir = new File(projectOutputDirectory/*from MavenProject*/, "META-INF/bundled-dependencies/native");
    final File libsoFile = new File(nativeDir, "lib" + libname + ".so");
    final File dllFile = new File(nativeDir, libname + ".dll");
    final File soFile = new File(nativeDir, libname + ".so");
    if (libsoFile.exists())
        return libsoFile.getAbsolutePath();
    else if (dllFile.exists())
        return dllFile.getAbsolutePath();
    else if (soFile.exists())
        return soFile.getAbsolutePath();
    return null;
}