native-maven-plugin throws error: gu.cmd' tool was not found.

[alexFilichkin]

Description native-maven-plugin throws error: gu.cmd' tool was not found. It happens because in Graalvm jdk21 gu was removed. https://github.com/oracle/graal/issues/6855**

System Info (please complete the following information):

• OS: [e.g. Windows]
• GraalVM Version [e.g. graalvm-jdk-21.0.0]
• Java Version [e.g. 21]
• Plugin version [e.g. native-maven-plugin:0.9.27]

Additional context

native-image --version native-image 21 2023-09-19 GraalVM Runtime Environment GraalVM CE 21+35.1 (build 21+35-jvmci-23.1-b15) Substrate VM GraalVM CE 21+35.1 (build 21+35, serial gc)

[kpoalses]

Happens under macOS as well. GraalVM for JDK 21: OpenJDK Runtime Environment GraalVM CE 21+35.1 (build 21+35-jvmci-23.1-b15) Maven plugin: org.graalvm.buildtools:native-maven-plugin:0.9.27

mvn -Pnative package Results in Failed to execute goal org.graalvm.buildtools:native-maven-plugin:0.9.27:compile-no-fork (build-native) ...elided... 'gu' tool was not found. This probably means that JDK at is not a GraalVM distribution.

Noted this on GraalVM Slack: https://graalvm.slack.com/archives/CNBFR78F9/p1695985908702449

[fniephaus]

I can't seem to reproduce this. What JAVA_HOME and/or GRAALVM_HOME (if any) are you using?

[kpoalses]

I can't seem to reproduce this. What JAVA_HOME and/or GRAALVM_HOME (if any) are you using?

Ah, therein lies the rub! I use jenv to switch between JDK versions, and this works fine for almost anything else built by grade, maven and leiningen. It seems Graal Native Tools needs JAVA_HOME to be managed as well.

For future reference by others suffering PEBCAK, fixed by using

jenv enable-plugin export

The GraalVM build tools are now happy, thanks.

[fniephaus]

Good to know there's a workaround, @kpoalses. Nonetheless, we'd like to make sure the plugins are as easy to use as possible, so it'd be good for us to know what exactly went wrong on your end. What JAVA_HOME/GRAALVM_HOME combination did not work?

[kpoalses]

Good to know there's a workaround, @kpoalses. Nonetheless, we'd like to make sure the plugins are as easy to use as possible, so it'd be good for us to know what exactly went wrong on your end. What JAVA_HOME/GRAALVM_HOME combination did not work?

For clarity, without the export plugin, jenv only updates the JDK shims to point at the correct JDK binaries (java, java, jlink etc), it _doesn't set JAVAHOME at all, and other tooling (mvn, gradle, etc) infer the JAVA_HOME from the binary path, so for example:

/Library/Java/JavaVirtualMachines/graalvm-community-openjdk-21+35.1/Contents/Home/bin/java would have an inferred JAVA_HOME of /Library/Java/JavaVirtualMachines/graalvm-community-openjdk-21+35.1/Contents/Home

and /Library/Java/JavaVirtualMachines/temurin-20.jdk/Contents/Home/bin/java would have an inferred JAVA_HOME of /Library/Java/JavaVirtualMachines/temurin-20.jdk/Contents/Home

In my problem case, although Maven was able to infer JAVA_HOME to be /Library/Java/JavaVirtualMachines/graalvm-community-openjdk-21+35.1/Contents/Home, and would happily compile, execute tests etc, the GraalVM Native tooling did not infer the JAVA_HOME, and went on to complain about gu.

With JAVA_HOME explicitly set (manually or using the jenv plugin) the GraalVM native tooling behaves correctly.

As I said, entirely my fault, although the error message regarding 'gu' tool not being found was a bit misleading - perhaps an outright complaint about lack of JAVA_HOME or GRAALVM_HOME not being set would be more helpful.

[fniephaus]

As I said, entirely my fault, although the error message regarding 'gu' tool not being found was a bit misleading - perhaps an outright complaint about lack of JAVA_HOME or GRAALVM_HOME not being set would be more helpful.

Yes, that sounds reasonable. The error message should remind users to check their JAVA/GRAALVM env vars, I'll take care of that. Thanks for the feedback!