Add exhaustive tests for linux (deb) aarch64 artifacts

[donoghuc]

Release notes

[rn:skip]

What does this PR do?

This commit extends the aarch64 pipeline to build a .deb for aarch64 on an x86 VM then run the exhaustive tests on aarch64 VM with the .deb. This replicates how artifacts are prepared in DRA on x86. This is net new in that it adds exhaustive tests for an aarch platform. This would have caught a recent packaging bug. More thourough tests will be added in the future, this is just a first step to get toward that goal.

Related Issues

• Enhance test coverage for logstash artifacts #18729
• Respect ARCH env var when downloading JDK via gradle #18733
• [WIP] Run exhaustive tests on arm linux #18740

Closes #18745

[github-actions]

🤖 GitHub comments

Just comment with:

• run docs-build : Re-trigger the docs validation. (use unformatted text in the comment!)
• /run exhaustive tests : Run the exhaustive tests Buildkite pipeline.

[mergify]

This pull request does not have a backport label. Could you fix it @donoghuc? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-8./d is the label to automatically backport to the 8./d branch. /d is the digit.
• If no backport is necessary, please add the backport-skip label

[donoghuc]

This example CI run shows this approach working https://buildkite.com/elastic/logstash-aarch64-pipeline/builds/623

You can see in the build step the wrong JDK is downloaded (it matches the x86 HOST rather than the ARCH env var:

2026-02-05 12:50:46 PST | > Task :downloadJdk
-- | --
2026-02-05 12:50:46 PST | Downloaded to /opt/buildkite-agent/builds/bk-agent-prod-gcp-1770324452919324750/elastic/logstash-aarch64-pipeline/build/jdk-21.0.9-linux-x64.tar.gz

The resulting .deb built for aarch86 (containing the JDK for x86) is downloaded by the next step

and fails with the expected pattern:

2026-02-05 13:05:28 PST | +Using bundled JDK: /usr/share/logstash/jdk
-- | --
2026-02-05 13:05:28 PST | +/usr/share/logstash/bin/logstash-plugin: 1: exec: /usr/share/logstash/jdk/bin/java: Exec format error

As proved in #18740 the exhaustive tests will pass when they have the right JDK. Once #18733 is merged this pipeline will start to pass.

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: e57d11a

[donoghuc]

Folding this in to #18733 as it is helpul for validating build changes and for backports.