Prevent two release jobs from overwriting the same environment
Two commits deploy simultaneously. The older job finishes last and marks its artifact current after the newer release already passed validation.
- Focused work estimate
- 3h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Distributed leases · Fencing · CI concurrency
Estimated field mix
- Platform engineering50%
- Distributed systems50%
Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence.
Review it, then add it to your workspace.
The board opens an editable draft; nothing is saved until you confirm it. Sign-in and workspace permissions apply, and Demo boards remain ephemeral.
Project context
A fictional scheduling service has an API, a worker, and PostgreSQL. Releases use immutable images on two application instances. The team needs compatibility checks, staged traffic, and a rehearsed rollback without introducing a new orchestration platform.
Setup prerequisites
- HTTP health checks
- CI pipelines
- Database migrations
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- Serialize mutations per environment with a bounded renewable lease.
- Reject state updates from expired or superseded lease holders.
- Record the winning release identity and every rejected stale update.
Implementation constraints
- A process-local mutex cannot coordinate independent CI jobs.
Verification to include
- Race two simulated releases and inspect one current manifest.
- Expire a lease, acquire a successor, and prove the old holder cannot publish.
Deliverables
- Release lease protocol and stale-writer regression
Rollout and recovery
Enable serialization on the test environment; disable dispatch while investigating lease failures.
Value of the work
For the engineer: Practice release contracts, compatibility windows, measurable canaries, and incident decisions on a modest application topology.
For the team: Review whether an engineer can make deployments diagnosable and reversible while identifying when rollback is unsafe.
Evidence boundaries
Outcome Evidence: Tests, patches, and runbooks are requested deliverables. They become Outcome Evidence only through a qualified Mission and immutable Evidence IDs.
Ownership Evidence: Independent adaptation must be observed under a declared verification policy and cite immutable Evidence IDs. Completing a planning ticket establishes no Ownership Evidence.