ci: add arm64 unit test jobs and run all flavors on Oracle VM runners

[arthurschreiber]

Description

This adds arm64 coverage to the unit test workflow and moves all unit test flavors onto the 16-CPU Oracle VM runners when running inside vitessio/vitess.

Two new matrix entries run the mysql80 unit tests (with and without the evalengine) on arm64. Oracle's apt repo only publishes amd64 packages for Ubuntu, so on arm64 the setup-mysql action now installs MySQL 8.0 from the Ubuntu archive instead — that's also why arm64 coverage is limited to mysql80 for now (no 5.7 or 8.4 packages exist for arm64; adding 8.4 would need Oracle's generic aarch64 tarballs).

Once we've got this up and running, I think it might make sense to investigate installing MySQL via the aarch64 tarballs on ARM64 instead to also get MySQL 8.4 unit tests running against ARM64.

Previously only the race jobs ran on oracle-vm-16cpu-64gb-x86-64. Now all jobs use the Oracle VMs in-repo, picking -x86-64 or -arm64 based on the matrix arch. Forks keep using the GitHub-hosted ubuntu-24.04 / ubuntu-24.04-arm runners.

Related Issue(s)

N/A

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

Deployment Notes

N/A — CI-only change.

AI Disclosure

This PR was written by Claude Code, with direction and review from me.

[vitess-bot]

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[Copilot]

Pull request overview

This PR expands CI unit-test coverage by adding arm64 unit-test jobs (MySQL 8.0 only) and standardizes runner selection so that, in vitessio/vitess, all unit-test flavors run on the 16‑CPU Oracle VM runners (x86_64 or arm64 depending on the matrix entry). It also updates the internal MySQL setup composite action to install MySQL differently on arm64, since Oracle’s apt repo does not publish arm64 Ubuntu packages.

Changes:

• Add two new arm64 matrix entries for mysql80 unit tests (with and without evalengine).
• Switch unit-test runner selection to Oracle VM runners for all matrix variants when running in-repo, with arch-aware runner selection.
• Update the setup-mysql composite action to install MySQL 8.0 from Ubuntu archives on arm64, while preserving Oracle apt-repo installation on amd64.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
.github/workflows/unit_test.yml	Adds arm64 unit-test matrix entries and updates runs-on / job naming to be arch-aware and to use Oracle VM runners in-repo.
.github/actions/setup-mysql/action.yml	Adds arm64-aware install path (Ubuntu archive MySQL 8.0 only) and keeps Oracle apt-repo install flow for amd64 flavors.

[arthurschreiber]

This seems to have uncovered a flaky behavior in the connection pool code on ARM64:

=== RUN   TestStressCloseDuringTraffic/cycle-054
2026-06-10 09:46:01.128 UTC ERR smartconnpool/pool.go:375 failed to reopen pool "": Code: ABORTED
timed out while waiting for connections to be returned to the pool (capacity=0, active=6, borrowed=0)

    stress_test.go:1016: 
        	Error Trace:	/home/ubuntu/_work/vitess/vitess/go/pools/smartconnpool/stress_test.go:1183
        	            				/home/ubuntu/_work/vitess/vitess/go/pools/smartconnpool/stress_test.go:1016
        	Error:      	Condition never satisfied
        	Test:       	TestStressCloseDuringTraffic/cycle-054
        	Messages:   	cycle 54: CloseWithContext stalled: capacity=0 active=10 borrowed=0 open=144 isOpen=true liveGetWorkers=24 capacityInProgress=true connectsAfterClose=0
    stress_test.go:1016: 
        	Error Trace:	/home/ubuntu/_work/vitess/vitess/go/pools/smartconnpool/stress_test.go:1193
        	            				/home/ubuntu/_work/vitess/vitess/go/pools/smartconnpool/stress_test.go:1016
        	Error:      	CloseWithContext stalled
        	Test:       	TestStressCloseDuringTraffic/cycle-054
        	Messages:   	cycle 54: capacity=0 active=6 borrowed=0 open=149 isOpen=false liveGetWorkers=0 capacityInProgress=false connectsAfterClose=5
--- FAIL: TestStressCloseDuringTraffic/cycle-054 (30.01s)

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.