Support for the Java LDAP client

[tobiasstadler]

What does this PR do?

I added support for instrumenting the Java LDAP client

Checklist

• This is an enhancement of existing features, or a new feature in existing plugins
  • I have updated CHANGELOG.asciidoc
  • I have added tests that prove my fix is effective or that my feature works
  • Added an API method or config option? Document in which version this will be introduced
  • I have made corresponding changes to the documentation

[github-actions]

👋 @tobiasstadler Thanks a lot for your contribution!

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Build stats

• Reason: null

• Start Time: 2022-01-28T08:47:23.776+0000

• Duration: 49 min 27 sec

• Commit: 2490158

Test stats 🧪

Test	Results
Failed	0
Passed	2461
Skipped	16
Total	2477

💚 Flaky test report

Tests succeeded.

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[tobiasstadler]

@felixbarny Could you please review this PR also?

[felixbarny]

run elasticsearch-ci/docs

[tobiasstadler]

Thank you!

[felixbarny]

Seems like IntelliJ has issues with the imports from the java.naming/com.sun.jndi.ldap module.

Applying the suggestion only works until the maven project is reloaded.

I've tried adding

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <compilerArgs>
                        <arg>--add-exports</arg>
                        <arg>java.naming/com.sun.jndi.ldap=ALL-UNNAMED</arg>
                    </compilerArgs>
                </configuration>
            </plugin>
        </plugins>
    </build>

But that yields this error: java: exporting a package from system module java.naming is not allowed with --release

@tobiasstadler Did you manage to get this work in an IDE?

[tobiasstadler]

Can you please try adding <maven.compiler.source>1.7</maven.compiler.source> to the properties of the plugin pom?

[tobiasstadler]

The problem probably is that the IntelliJ profile in the parent pom sets maven.compiler.target and maven.compiler.target to 11.

[felixbarny]

Ah, right. This works. However, only with a Java 11 compiler. With Java 17 there are still a few issues. Under Preferences > Build, Execution, Deployment > Compiler > Java Compiler, I had to uncheck the Use '--release' option for cross-compilation option. But even after doing that, the tests fail with an IllegalAccessError:

java.lang.IllegalAccessError: class co.elastic.apm.agent.java_ldap.LdapClientAdvice (in unnamed module @0x25be445f) cannot access class com.sun.jndi.ldap.Connection (in module java.naming) because module java.naming does not export com.sun.jndi.ldap to unnamed module @0x25be445f
	at co.elastic.apm.agent.java_ldap.LdapClientAdvice.onEnter(LdapClientAdvice.java:55)
	at java.naming/com.sun.jndi.ldap.LdapClient.authenticate(LdapClient.java:153)
    ...

This will fail the Java 17 compatibility tests and it's probably also an issue in production with Java 17.

[tobiasstadler]

I just tested it with Java17. It compiles fine but the tests are failing with the error you mentioned.

[tobiasstadler]

#2430