[Backend] Health: deep readiness probe covering Postgres, Redis, and Horizon listener liveness

[Baskarayelu]

Description

The health router (src/routes/health.ts, src/services/health/probes.ts, checks.ts) provides probes, but the Horizon listener's liveness (last event/cursor heartbeat) and outbox publisher lease health are not represented. Kubernetes (k8s/deployment.yaml) can route traffic to a pod whose listener has silently died or whose outbox is stalled, so readiness must reflect background-worker health, not just process up.

Requirements and context

• Add readiness checks for: Postgres connectivity (src/db/pool.ts), Redis (src/cache/redis.ts), Horizon listener last-heartbeat age, and outbox publisher running state.
• Distinguish liveness (process up) from readiness (dependencies + workers healthy) in src/services/health/probes.ts.
• Surface degraded subsystems in the JSON body with per-check status.
• Align with k8s/deployment.yaml probe paths.

Suggested execution

Create branch feature/deep-readiness-probes.

• Extend src/services/health/checks.ts and probes.ts.
• Expose listener/outbox heartbeats for the checks to read.
• Extend tests/routes/health.test.ts and src/services/health/checks.test.ts.
• Update docs/k8s.md and docs/monitoring.md.

Test and commit

Run npm run test. Edge cases: Redis down → ready=false, listener heartbeat stale, partial degradation. Security: health body must not leak connection strings.

Example commit message

feat: deep readiness probe including listener and outbox health

Guidelines

• Minimum 95% test coverage
• Clear documentation in docs/k8s.md
• Timeframe: 96 hours

[d3vobed]

@d3vobed has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Hi, I’d like to work on this issue.

I can implement deep readiness probes covering Postgres, Redis, Horizon listener heartbeat, and outbox publisher health, while clearly separating liveness vs readiness checks. I’ll also add detailed subsystem status reporting, extend test coverage for degraded scenarios, and update the Kubernetes/monitoring documentation accordingly.

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[drips-wave]

Congratulations, @d3vobed! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

🧑‍💻 @d3vobed: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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