git.stella-ops.org/docs/modules/orchestrator/architecture.md

Source & Job Orchestrator architecture

Based on Epic 9 – Source & Job Orchestrator Dashboard; this section outlines components, job lifecycle, rate-limit governance, and observability.

1) Topology

• Orchestrator API (StellaOps.Orchestrator). Minimal API providing job state, throttling controls, replay endpoints, and dashboard data. Authenticated via Authority scopes (orchestrator:*).
• Job ledger (PostgreSQL). Tables jobs, job_history, sources, quotas, throttles, incidents (schema orchestrator). Append-only history ensures auditability.
• Queue abstraction. Supports Valkey Streams or NATS JetStream (pluggable). Each job carries lease metadata and retry policy.
• Dashboard feeds. SSE/GraphQL endpoints supply Console UI with job timelines, throughput, error distributions, and rate-limit status.

2) Job lifecycle

1. Enqueue. Producer services (Concelier, Excititor, Scheduler, Export Center, Policy Engine) submit JobRequest records containing jobType, tenant, priority, payloadDigest, dependencies.
2. Scheduling. Orchestrator applies quotas and rate limits per {tenant, jobType}. Jobs exceeding limits are staged in pending queue with next eligible timestamp.
3. Leasing (Task Runner bridge). Workers poll LeaseJob endpoint; Orchestrator returns job with leaseId, leaseUntil, idempotencyKey, and instrumentation tokens. Lease renewal required for long-running tasks; leases carry retry hints and provenance (tenant, project, correlationId, taskRunnerId).
4. Completion. Worker reports status (succeeded, failed, canceled, timed_out). On success the job is archived; on failure Orchestrator applies retry policy (exponential backoff, max attempts). Incidents escalate to Ops if thresholds exceeded.
5. Replay. Operators trigger POST /jobs/{id}/replay which clones job payload, sets replayOf pointer, and requeues with high priority while preserving determinism metadata.

Pack-run lifecycle (phase III)

• Register pack-run job type with task runner hints (artifacts, log channel, heartbeat cadence).
• Logs/Artifacts: SSE/WS stream keyed by packRunId + tenant/project; artifacts published with content digests and URI metadata.
• Events: notifier payloads include envelope provenance (tenant, project, correlationId, idempotencyKey) pending ORCH-SVC-37-101 final spec.

3) Rate-limit & quota governance

• Quotas defined per tenant/profile (maxActive, maxPerHour, burst). Stored in quotas and enforced before leasing.
• Dynamic throttles allow ops to pause specific sources (pauseSource, resumeSource) or reduce concurrency.
• Circuit breakers automatically pause job types when failure rate > configured threshold; incidents generated via Notify and Observability stack.
• Control plane quota updates require Authority scope orch:quota (issued via Orch.Admin role). Historical rebuilds/backfills additionally require orch:backfill and must supply backfill_reason and backfill_ticket alongside the operator metadata. Authority persists all four fields (quota_reason, quota_ticket, backfill_reason, backfill_ticket) for audit replay.

3.1) Quota governance service

The QuotaGovernanceService provides cross-tenant quota allocation with configurable policies:

Allocation strategies:

• Equal — Divide total capacity equally among all active tenants.
• Proportional — Allocate based on tenant weight/priority tier.
• Priority — Higher priority tenants get allocation first, with preemption.
• ReservedWithFairShare — Reserved minimum per tenant, remainder distributed fairly.
• Fixed — Static allocation per tenant regardless of demand.

Key operations:

• CalculateAllocationAsync — Compute quota for a tenant based on active policies.
• RequestQuotaAsync — Request quota from shared pool; returns granted amount with burst usage.
• ReleaseQuotaAsync — Return quota to shared pool after job completion.
• CanScheduleAsync — Check scheduling eligibility combining quota and circuit breaker state.

Quota allocation policy properties:

• TotalCapacity — Pool size to allocate from (for proportional/fair strategies).
• MinimumPerTenant / MaximumPerTenant — Allocation bounds.
• ReservedCapacity — Guaranteed capacity for high-priority tenants.
• AllowBurst / BurstMultiplier — Allow temporary overallocation when capacity exists.
• Priority — Policy evaluation order (higher = first).
• JobType — Optional job type filter (null = applies to all).

3.2) Circuit breaker service

The CircuitBreakerService implements the circuit breaker pattern for downstream services:

States:

• Closed — Normal operation; requests pass through. Failures are tracked.
• Open — Circuit tripped; requests are blocked for OpenDuration. Prevents cascade failures.
• HalfOpen — After open duration, limited test requests allowed. Success → Closed; Failure → Open.

Thresholds:

• FailureThreshold (0.0–1.0) — Failure rate that triggers circuit open.
• WindowDuration — Sliding window for failure rate calculation.
• MinimumSamples — Minimum requests before circuit can trip.
• OpenDuration — How long circuit stays open before half-open transition.
• HalfOpenTestCount — Number of test requests allowed in half-open state.

Key operations:

• CheckAsync — Verify if request is allowed; returns CircuitBreakerCheckResult.
• RecordSuccessAsync / RecordFailureAsync — Update circuit state after request.
• ForceOpenAsync / ForceCloseAsync — Manual operator intervention (audited).
• ListAsync — View all circuit breakers for a tenant with optional state filter.

Downstream services protected:

• Scanner
• Attestor
• Policy Engine
• Registry clients
• External integrations

4) APIs

4.1) Job management

• GET /api/jobs?status= — list jobs with filters (tenant, jobType, status, time window).
• GET /api/jobs/{id} — job detail (payload digest, attempts, worker, lease history, metrics).
• POST /api/jobs/{id}/cancel — cancel running/pending job with audit reason.
• POST /api/jobs/{id}/replay — schedule replay.
• POST /api/limits/throttle — apply throttle (requires elevated scope).
• GET /api/dashboard/metrics — aggregated metrics for Console dashboards.

4.2) Circuit breaker endpoints (/api/v1/orchestrator/circuit-breakers)

• GET / — List all circuit breakers for tenant (optional ?state= filter).
• GET /{serviceId} — Get circuit breaker state for specific downstream service.
• GET /{serviceId}/check — Check if requests are allowed; returns IsAllowed, State, FailureRate, TimeUntilRetry.
• POST /{serviceId}/success — Record successful request to downstream service.
• POST /{serviceId}/failure — Record failed request (body: failureReason).
• POST /{serviceId}/force-open — Manually open circuit (body: reason; audited).
• POST /{serviceId}/force-close — Manually close circuit (audited).

4.3) Quota governance endpoints (/api/v1/orchestrator/quota-governance)

• GET /policies — List quota allocation policies (optional ?enabled= filter).
• GET /policies/{policyId} — Get specific policy.
• POST /policies — Create new policy.
• PUT /policies/{policyId} — Update policy.
• DELETE /policies/{policyId} — Delete policy.
• GET /allocation — Calculate allocation for current tenant (optional ?jobType=).
• POST /request — Request quota from pool (body: jobType, requestedAmount).
• POST /release — Release quota back to pool (body: jobType, releasedAmount).
• GET /status — Get tenant quota status (optional ?jobType=).
• GET /summary — Get quota governance summary across all tenants (optional ?policyId=).
• GET /can-schedule — Check if job can be scheduled (optional ?jobType=).

4.4) Discovery and documentation

• Event envelope draft (docs/modules/orchestrator/event-envelope.md) defines notifier/webhook/SSE payloads with idempotency keys, provenance, and task runner metadata for job/pack-run events.
• OpenAPI discovery: /.well-known/openapi exposes /openapi/orchestrator.json (OAS 3.1) with pagination/idempotency/error-envelope examples; legacy job detail/summary endpoints now ship Deprecation + Link headers that point to their replacements.

All responses include deterministic timestamps, job digests, and DSSE signature fields for offline reconciliation.

5) Observability

• Metrics: job_queue_depth{jobType,tenant}, job_latency_seconds, job_failures_total, job_retry_total, lease_extensions_total.
• Task Runner bridge adds pack_run_logs_stream_lag_seconds, pack_run_heartbeats_total, pack_run_artifacts_total.
• Logs: structured with jobId, jobType, tenant, workerId, leaseId, status. Incident logs flagged for Ops.
• Traces: spans covering enqueue, schedule, lease, worker_execute, complete. Trace IDs propagate to worker spans for end-to-end correlation.

6) Offline support

• Orchestrator exports audit bundles: jobs.jsonl, history.jsonl, throttles.jsonl, manifest.json, signatures/. Used for offline investigations and compliance.
• Replay manifests contain job digests and success/failure notes for deterministic proof.

7) Operational considerations

• HA deployment with multiple API instances; queue storage determines redundancy strategy.
• Support for maintenance mode halting leases while allowing status inspection.
• Runbook includes procedures for expanding quotas, blacklisting misbehaving tenants, and recovering stuck jobs (clearing leases, applying pause/resume).