java_tools should have prebuilt Linux AArch64 binaries

[timothyg-stripe]

Currently, only four platforms have prebuilt java_tools binaries (singlejar, ijar, etc.): linux, windows, darwin_x86_64, darwin_arm64.

https://github.com/bazelbuild/rules_java/blob/3c34c81569e72f9984d7bdbcfd93d172ba685e4b/java/repositories.bzl#L27-L51

However, other parts of rules_java supports more platforms, like remotejdk21 which additionally supports Linux AArch64. It would be great if rules_java can distribute prebuilt Linux AArch64 binaries for java_tools, bringing it inline with JDK.

[guw]

Is this a matter of enabling the build process to produce the binaries and release them or is the development work necessary to implement missing native support?

[timothyg-stripe]

I'm guessing it's just a matter of enabling the build process. I haven't tried running it on AArch64, but I'd be surprised if there's any incompatibility.

[fmeum]

Since GraalVM can't cross-compile native images, at least for full parity this would require having real Linux AArch64 machines in Bazel CI.

cc @meteorcloudy

[guw]

As a workaround for now use https://github.com/bazelbuild/rules_java/blob/02df6937cda3f627a47d42391b09b7da0fe3b849/toolchains/default_java_toolchain.bzl#L124 with care

[meteorcloudy]

We do have two Linux Arm64 machines on Bazel CI, one in the normal Bazel unstrusted org, another in the trusted org for release builds. You can use them by ubuntu2004_arm64 platform name.