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shankar0123
35e18bfc56
Closes the #9 acquisition-readiness blocker from the 2026-05-01 issuer coverage audit. Pre-fix, JobService.ProcessPendingJobs ran every claimed job sequentially in a single goroutine: safe but slow, and operators with large fleets had no lever to dial throughput up. Switching to fire-and-forget per-job goroutines would have unbounded the upstream-CA call rate and tripped DigiCert / Entrust / Sectigo rate limits — certctl's response to 429 was to retry on the next tick, re-fanning out the same calls and digging deeper into the limit. Operators need a knob. This commit: - Adds CERTCTL_RENEWAL_CONCURRENCY env var (default 25) loaded via the existing getEnvInt pattern in internal/config/config.go. Documented inline as the cap for the per-tick renewal/issuance/ deployment goroutine fan-out, with operator-tuning guidance: permissive upstream limits + large fleets (>10k certs) → 100; strict limits or async-CA-heavy fleets → 25 or lower. - Wires golang.org/x/sync/semaphore.Weighted around the per-job goroutine launch in JobService.ProcessPendingJobs. Acquire(ctx, 1) is the load-bearing piece — it BLOCKS the loop when at the cap, providing real backpressure rather than fire-and-forget. The fan-out is split into processPendingJobsSequential (legacy, preserved for unit-test wiring that doesn't call SetRenewalConcurrency) and processPendingJobsConcurrent (production, delegates to a generic boundedFanOut helper). - boundedFanOut takes the per-job work as a closure so the cap can be tested directly without standing up the renewal/deployment service graph. processed/failed counters use atomic.Int64 to avoid mutex overhead on every job completion; final log line reads both AFTER wg.Wait so the counts reflect every dispatched job. ctx-aware Acquire ensures a shutdown ctx cancel interrupts the dispatch loop promptly; in-flight goroutines drain via Wait before the function returns so no goroutine outlives the scheduler tick. - shouldSkipJob extracted as a package-private helper so the agent-routed-deployment skip logic is shared between the sequential and concurrent paths byte-for-byte (the audit prompt's "channel-based semaphore without ctx-aware acquire" anti-pattern is explicitly avoided — semaphore.Weighted.Acquire returns on ctx done; channel <- struct{}{} would block forever). - SetRenewalConcurrency setter on JobService normalises ≤0 to 1. semaphore.NewWeighted(0) constructs a semaphore that blocks every Acquire forever; the normalisation prevents a misconfigured env var from wedging the scheduler. - cmd/server/main.go wires SetRenewalConcurrency(cfg.Scheduler. RenewalConcurrency) on the freshly-built jobService, immediately after SetAuditService. Production deployments always take the bounded path; tests that build JobService directly via NewJobService keep their strict-sequential behaviour because renewalConcurrency is the zero value. - Tests in internal/service/job_concurrency_test.go: * TestBoundedFanOut_CapHolds — primary regression guard. 50 jobs × 50ms work × cap=5 → asserts peak in-flight never exceeds 5 AND reaches 5 at least once (catches both upper-bound regressions and gates that incorrectly cap below the configured value). Lock-free max via CompareAndSwap so the measurement instrument doesn't itself constrain concurrency. * TestBoundedFanOut_AllJobsRun — lower-bound: every non-skipped job is dispatched. * TestBoundedFanOut_SkipsAgentRoutedDeployments — pins the shouldSkipJob contract. * TestBoundedFanOut_CtxCancelInterrupts — ctx cancellation interrupts a stuck fan-out within the timeout budget. * TestBoundedFanOut_FailedJobsCounted — per-job errors don't abort the fan-out. * TestSetRenewalConcurrency_NormalizesNonPositive — ≤0 → 1 fail-safe pinned across negative/zero/positive inputs. - docs/features.md: scheduler-loop table augmented with the concurrency-cap env-var pointer alongside the job-processor row. - docs/architecture.md: Concurrency Safety section gains a paragraph explaining the cap, the operator-tuning guidance, the ctx-aware Acquire semantics, and the audit reference. Operator-facing impact: the first big renewal sweep no longer takes down the upstream CA's rate-limit budget. Existing deployments get the bounded path automatically (default 25); operators can override via env var without code changes. Verified locally: - gofmt -l . clean - go vet ./... clean - staticcheck ./... clean - go test -short -count=1 across service / scheduler / config / integration: green - Six new tests under TestBoundedFanOut* + TestSetRenewalConcurrency*: green Audit reference: cowork/issuer-coverage-audit-2026-05-01/RESULTS.md Top-10 fix #9.