Every publish-platform-image run since the 3ff40c4 self-hosted runner
migration has been failing with two runner-level issues that the
workflow now works around (keychain) or surfaces clearly (path):
1. "error storing credentials - err: exit status 1, out:
'User interaction is not allowed. (-25308)'"
docker/login-action tries to persist the GHCR + Fly tokens in the
macOS Keychain, but the Mac mini runner runs as a non-interactive
launchd service without an unlocked desktop session — keychain
access raises -25308. Fix: set DOCKER_CONFIG to a per-run temp dir
containing a plain config.json before the login step so credentials
land in a file, not the keychain. This is the same trick the
GitHub-hosted macos runners use in docker action examples.
2. "Unexpected error attempting to determine if executable file
exists '/usr/local/bin/docker': Error: EACCES: permission denied,
stat '/usr/local/bin/docker'"
Not a workflow bug — the runner literally can't read the Docker
binary path. Adds a diagnostic step before QEMU/buildx setup that
prints: PATH, `command -v docker`, `docker --version`, and
`ls -la` on both /usr/local/bin/docker and /opt/homebrew/bin/docker.
Surfacing these in the log means the next failure (if any) shows
the actual problem instead of hiding behind a cryptic buildx error.
Does NOT fix the root cause of #2 — that needs the user to SSH into
the Mac mini runner and reinstall / re-permission Docker Desktop
(or switch to Colima/OrbStack). The diagnostic output will tell us
exactly which path is broken.
The 20+ queued CI runs from `ci.yml` are unrelated to this PR — they
are stuck because the self-hosted runner has severely degraded queue
throughput (runs wait 2+ hours before being picked up). That's a
separate runner-health issue tracked as a user action in the triage
report.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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