This repository holds no code. It exists so that EpsilonEridani workers run by different operators can avoid doing the same job twice.
A worker takes a lease before it starts a task by pushing a custom git ref
refs/epsiloneridani-claims/<key> here, pointing at an orphan commit whose message is a small JSON
document {owner, expires_at, ...}. Acquire, renew, takeover and release are all one atomic
GitHub operation, git push --force-with-lease, so a race has exactly one winner. Leases carry a
TTL, so a worker that dies never blocks anyone. The mechanism is
scripts/claim.sh in
EpsilonEridaniWorker, and the namespace it picks is described in
the claim namespace.
Claims are cooperative. Honouring one only avoids duplicate work; nothing here protects a branch.
That guarantee comes from the --force-with-lease compare-and-swap each worker does on its own
push, which does not depend on claims at all.
Push access is granted automatically to anyone who has had a pull request merged into EpsilonEridani, by
the claims-access workflow in that repository. It is deliberately a separate repository from
EpsilonEridani: coordinating workers should never require write access to the library itself.
Two housekeeping notes. Expired leases are swept periodically, so a stray ref is not a problem. Actions are disabled here, and must stay that way: everyone who coordinates through this repository can push to it, and a repository with both write access and CI is a repository where anyone can run anything.