Environment variables defined in toolchains.xml are incorrect on ARM runners

[hfhbd]

The toolchain.xml contains x86 env variables which aren't guaranteed to exist on arm, like macOS-14 (M1) or Ubuntu Arm runners (currently in private Beta), or on any custom hosted runner:

<!-- JDK Toolchains installed by default on GitHub-hosted runners -->
  <toolchain>
    <type>jdk</type>
    <provides>
      <version>8</version>
      <vendor>Eclipse Temurin</vendor>
    </provides>
    <configuration>
      <jdkHome>${env.JAVA_HOME_8_X64}</jdkHome>
    </configuration>
  </toolchain>

When using Gradle, this results into these warnings on macOS-14 (M1)/Ubuntu Arm:

Directory '/home/runner/.gradle/daemon/8.7-rc-3/${env.JAVA_HOME_8_X64}' (Maven Toolchains) used for java installations does not exist
Directory '/home/runner/.gradle/daemon/8.7-rc-3/${env.JAVA_HOME_21_X64}' (Maven Toolchains) used for java installations does not exist
Directory '/home/runner/.gradle/daemon/8.7-rc-3/${env.JAVA_HOME_11_X64}' (Maven Toolchains) used for java installations does not exist
Directory '/home/runner/.gradle/daemon/8.7-rc-3/${env.JAVA_HOME_17_X64}' (Maven Toolchains) used for java installations does not exist

After using setup-java with 21, on Ubuntu Arm there is only one env: JAVA_HOME_21_ARM64=/home/runner/work/_tool/Java_Adopt_jdk/21.0.2-13.0.LTS/arm64

[bigdaz]

Thanks for your report. The reason for the hard-coded toolchains.xml file is to ensure that pre-installed JDKs are used when Gradle resolves a Java toolchain. Without this, Gradle will download a JDK even when the same one is already installed on the runner.

To support ARM equally, we need to choose between:

1. Removing this hard-coded list. Users will need to use setup-java (which adds to toolchains.xml) in order to benefit from pre-installed JDKs.
2. Add a separate hard-coded toolchains list for ARM.
3. Add the _arm equivalents to the hard-coded list, and validate against the actual environment, removing any that are unknown.

My preference would be for the 3rd option. Are you interested in submitting a PR for this?

[hfhbd]

Are you interested in submitting a PR for this?

Yes