test: demonstrate the regtest stack on a second GH runner - #205
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Alternative to provisioning a cloud VM, motivated by that approach needing
a GCP project and IAM access which is not always obtainable.
Three things had to hold and all three do:
- Two GitHub-hosted runners can reach each other. Both are behind NAT
with no inbound connectivity, so this goes over Tailscale; plain
WireGuard cannot traverse it. Peer addresses come from `tailscale
status` rather than MagicDNS, which the action cannot configure on
these runners.
- The stack job can outlive its own steps, by blocking on the tester's
job status. Neither job may declare needs: on the other or they
deadlock.
- An iOS Simulator can reach the tailnet, not just the Mac's shell.
The last is asserted by the stack runner against its own access log, on a
path the tester's shell does not fetch, so nothing on the Mac can satisfy
it locally.
Dispatch only, and independent of the VM tooling — this is evidence for
choosing between the two, not a second implementation.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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What this is
Evidence for a decision, not a second implementation. #204 runs the regtest stack on an ephemeral GCP VM; this shows the same thing working on a second GitHub-hosted runner, reached over Tailscale — which needs no cloud account at all.
Draft deliberately: if the team picks the VM route this should be closed, not merged.
Why it matters
The VM approach needs a GCP project and IAM access to configure Workload Identity Federation. That is an organisational dependency, not an engineering one, and it is currently the thing blocking #204 from running anywhere.
This route needs a tailnet and one repository secret.
Three things had to hold, and all three do
Verified on a real run:
tailscale status, not MagicDNS, because the action configures macOS DNS against a network service namedEthernetthat these runners do not have.needs:on the other or they deadlock — this is what broke the Oct 2025test/e2e-workflowattempt, which usedneeds:and lost its containers before any test ran.How the two compare
Everything test-side is shared between them — the compose change,
constants.ts,lnd.tsandwdio.conf.tsin #204 are identical either way. Only provisioning differs, so this is not a fork in the road that costs anything to defer.Setup, if you want to run it
secrets.TS_AUTHKEY— reusable, ephemeral, taggedtag:citag:cito reachtag:ciworkflow_dispatchonly. Merging it changes nothing on its own.Related