After consistent hashing (10 Oct), this post covers instance health probes: liveness vs readiness vs startup, dependency checks, shutdown order, timing, cheap handlers, metrics and synthetics contrast.

स्वास्थ्यप्रबोधः: A Metrical Codification of Health Probes (with English glosses)

What this post is about

Health probes (liveness readiness startup) tell orchestrators and load balancers whether an instance is alive and ready for traffic.

Topics covered

1. Dead instances still receiving traffic
2. Liveness vs readiness
3. Startup probes
4. Shallow vs deep dependency checks
5. Readiness-first on graceful shutdown
6. Period timeout thresholds
7. Cheap /health handlers
8. Probe metrics
9. Probes vs external synthetics
10. Deploy gates

Sanskrit title

स्वास्थ्यप्रबोधः = svāsthya-prabodhaḥ “health awakening / health probe”.

English

Minimizable details; Sanskrit-first default.

ग्राह्यम् / Keep

१. त्रिप्रबोधः: live/ready/start split
२. लघुपथः: cheap health handlers
३. मितनिर्भरता: no cascade-ready-all
४. shutdown क्रमः: ready false then drain
५. threshold विवेकः: avoid flap on blips
६. probe metrics: restarts NotReady
७. auth on /health: if exposed

त्याज्यम् / Avoid

• one probe does all three jobs
• health query full table scan
• liveness fail while still draining

पदच्छेदः
मृतं पात्रं यदि यातायातं गृह्णाति तदा जनो दह्यते । स्वास्थ्यप्रबोधस्तस्माद् द्वारसत्यम् ॥१॥

Word-for-word

Gloss table

English sense
Health probes tell the platform whether an instance may take traffic or must be restarted. Without them load balancers feed dead processes.

Context / topic
Topic: why probes exist. Distinct from external synthetics (3 Sep).

वृत्तमिति: ८-८-८-८।

पदच्छेदः
जीवचिह्नं प्रक्रियास्ति वा । तत्परता सेवा योग्यति वा ॥२॥

Word-for-word

Gloss table

English sense
Liveness asks if the process should be killed and restarted. Readiness asks if it should receive user traffic right now.

Context / topic
Topic: liveness vs readiness.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
प्रारम्भपरीक्षा धीरे आरम्भे । जीवहानौ मध्ये मा हन ॥३॥

Word-for-word

Gloss table

English sense
Startup probes protect slow boots from liveness kills before the app can listen.

Context / topic
Topic: startup probe.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
तत्परता निर्भरतां पश्येत् मितम् । सर्वDB बन्धे चक्रीयनाशः ॥४॥

Word-for-word

Gloss table

English sense
Optional shallow dependency checks in readiness can help. Deep checks on every shared DB can make whole fleets go NotReady together.

Context / topic
Topic: dependency checks in readiness.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
कृपानिष्क्रये तत्परता पूर्वं मृता जीवचिह्नं यावत् द्रवति । विमोचने क्रमः स एव ॥५॥

Word-for-word

Gloss table

English sense
On shutdown fail readiness first so traffic stops then drain in-flight work while liveness stays true. Matches graceful-shutdown dharma.

Context / topic
Topic: shutdown order.

सन्धिः: कृपानिष्क्रयः (१८ अगस्त).

वृत्तमिति: एकादशाक्षराः पादाः।

पदच्छेदः
कालसीमा अन्तरं असफलतासीमा लेख्याः । अतिशीघ्रं हनति स्पन्दने ॥६॥

Word-for-word

Gloss table

English sense
Tune period timeout and failure thresholds so a single GC blip does not flap the instance out of service.

Context / topic
Topic: probe timing.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
पथः लघुः /healthz न गुरुव्यापारः । पूर्णjoin स्वास्थ्ये विपत्तिः ॥७॥

Word-for-word

Gloss table

English sense
Health handlers must be cheap and locked down. Expensive health queries amplify load during outages.

Context / topic
Topic: cheap handlers.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
मापनं NotReady restart probe_fail । अदृश्यप्रबोधः अन्धविमोचनम् ॥८॥

Word-for-word

Gloss table

English sense
Alert on rising restart counts and sustained NotReady. Deploys without probe metrics are flying blind.

Context / topic
Topic: probe metrics.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
कृत्रिमनिरीक्षणं बहिः जनपथः । प्रबोधः आभ्यन्तरं द्वारम् ॥९॥

Word-for-word

Gloss table

English sense
Synthetics watch user journeys from outside. Probes watch instance fitness inside the orchestrator. Both needed.

Context / topic
Topic: probes vs synthetics.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
नीलाहरितं तत्परतां पश्यति पात्ररक्षा स्कैनं पृथक् । प्रबोधः यातायातस्य द्वाःपालः ॥१०॥

Word-for-word

Gloss table

English sense
Deploy color switches should wait on readiness. Image scans are a different gate than live probes.

Context / topic
Topic: deploy and security gates.

सन्धिः: विमोचनं तत्परतां; स्कैन जन्मनि।

वृत्तमिति: एकादशाक्षराः पादाः।

पदच्छेदः
जीवः तत्परता आरम्भः कालः मापनं पञ्चकम् । एभिः स्वास्थ्यप्रबोधो द्वारसत्यसमन्वितः ॥११॥

Word-for-word

Gloss table

English sense
Five limbs: liveness, readiness, startup, careful timing and probe metrics.

Context / topic
Topic: checklist.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
इति स्वास्थ्यप्रबोधसारो द्वारसत्यसमन्वितः । मितं प्रबोधं क्रियायोग्यं तन्त्रधर्मः स उच्यते ॥१२॥

Word-for-word

Gloss table

English sense
Closing: only ready instances should face users; only dead ones should be restarted.

Context / topic
Topic: close.

उपसंहारन्यायः: तत्परं वह; अजीवँ हन; मध्ये मा भ्रम।

वृत्तमिति: ८-८-८-८।

१. Why probes
२. Live vs ready
३. Startup
४. Deps
५. Shutdown order
६. Timing
७. Cheap path
८. Metrics
९. Synthetics
१०. Deploy
११. Five limbs
१२. Close

1. Prior: graceful shutdown 2026-08-18; synthetics 2026-09-03; blue-green 2026-08-19.
2. Domain: k8s-style health probes.
3. English minimizable; Sanskrit-first.
4. Style: no em dash; no Oxford comma in English clauses.