docs(design): ADR-050 — system-services-monitor scope - #1380
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📝 WalkthroughWalkthroughADR-050 defines a node-local ChangesSystem Services Monitor Scope Specification
Estimated code review effort: 2 (Simple) | ~10 minutes Merge Risk: 🟡 Moderate · up to The ADR’s event-processing contract does not yet define stable deduplication or ordering for retries and concurrent transitions, which could allow stale health updates or incorrect rollback behavior. Clarify this contract before merging. 🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
✨ Finishing Touches🧪 Generate unit tests (beta)
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Actionable comments posted: 3
🧹 Nitpick comments (1)
docs/designs/030-fabric-manager-monitor-scope.md (1)
189-196: ⚡ Quick winConsider adding concrete test scenarios for Phase 2 integration testing.
The Phase 2 testing criteria are clear but somewhat abstract. To ensure thorough validation, consider adding specific test scenarios, such as:
- Device-level fault isolation: Inject a PCIe link down event and verify only
gpu-health-monitoremits an event (notfabric-manager-monitor)- Service-level fault isolation: Stop the fabric-manager systemd unit and verify only
fabric-manager-monitoremitsFM_DOWN(notgpu-health-monitor)- State caching verification: Trigger the same fault repeatedly within a short window and verify each monitor emits exactly one event (deduplication working)
- gRPC schema compatibility: Verify both monitors' events deserialize correctly in
platform-connectorwithout schema version conflictsThese concrete scenarios would strengthen the integration test plan and provide clearer acceptance criteria for Phase 2.
🤖 Prompt for AI Agents
Verify each finding against current code. Fix only still-valid issues, skip the rest with a brief reason, keep changes minimal, and validate. In `@docs/designs/030-fabric-manager-monitor-scope.md` around lines 189 - 196, Add concrete Phase 2 integration test scenarios to the document: enumerate tests for device-level fault isolation (e.g., inject a PCIe link down and assert only gpu-health-monitor emits an event), service-level fault isolation (e.g., stop the fabric-manager systemd unit and assert only fabric-manager-monitor emits FM_DOWN), state-caching deduplication (trigger the same fault repeatedly and assert each monitor emits exactly one event), and gRPC schema compatibility (have platform-connector deserialize events from both monitors and verify no schema/version conflicts); include expected inputs, verification steps, and acceptance criteria for each scenario so they can be executed by CI or QA.
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Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
Inline comments:
In `@docs/designs/030-fabric-manager-monitor-scope.md`:
- Around line 154-166: The Event Model section currently lists checkName values
(FM_DOWN, FM_UNRESPONSIVE, FM_FLAPPING) but omits required HealthEvent fields
from health_event.proto; update the document to add a new "HealthEvent schema"
subsection that defines a complete HealthEvent for each checkName (FM_DOWN,
FM_UNRESPONSIVE, FM_FLAPPING) and explicitly sets the agent (e.g.,
"fabric-manager-monitor"), componentClass (e.g., "fabric-manager" or "service"),
isFatal (true/false per check), recommendedAction (CORDON/DRAIN/QUARANTINE as
appropriate), and processingStrategy (EXECUTE_REMEDIATION or STORE_ONLY), giving
one concrete example event payload per check so implementers and
platform-connector teams have an unambiguous contract.
- Around line 197-202: Set the Phase‑1 FM readiness default to require both the
systemd unit "nvidia-fabricmanager" being in the active state and the
fabric-state query indicating FM is responsive/progressing (i.e., not in the
FM_UNRESPONSIVE/stuck condition); update the "FM readiness definition" text to
state this combined criterion and note that explicit local API/socket probe
support is deferred to a future refinement rather than a Phase‑1 prerequisite.
- Around line 91-97: Update the design doc section that asserts DCGM-visible
signals remain in gpu-health-monitor to explicitly state the scope: confirm that
"future degradation-detection work" refers only to higher-level
policy/processing built on top of existing DCGM health watches
(DCGM_HEALTH_WATCH_PCIE, DCGM_HEALTH_WATCH_NVLINK, DCGM_HEALTH_WATCH_THERMAL)
and NOT reimplementing those watches in fabric-manager-monitor, and separately
call out any non-watch detection items (e.g., clock-throttling, other custom
sensors) as distinct prerequisites or parallel work items that must be tracked
if they remain out of scope for fabric-manager-monitor; reference the components
gpu-health-monitor and fabric-manager-monitor and list the specific DCGM watch
names so the scope is unambiguous.
---
Nitpick comments:
In `@docs/designs/030-fabric-manager-monitor-scope.md`:
- Around line 189-196: Add concrete Phase 2 integration test scenarios to the
document: enumerate tests for device-level fault isolation (e.g., inject a PCIe
link down and assert only gpu-health-monitor emits an event), service-level
fault isolation (e.g., stop the fabric-manager systemd unit and assert only
fabric-manager-monitor emits FM_DOWN), state-caching deduplication (trigger the
same fault repeatedly and assert each monitor emits exactly one event), and gRPC
schema compatibility (have platform-connector deserialize events from both
monitors and verify no schema/version conflicts); include expected inputs,
verification steps, and acceptance criteria for each scenario so they can be
executed by CI or QA.
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docs/designs/030-fabric-manager-monitor-scope.md
| │ ┌──────────────────────────────────────────────────────┐ │ │ | ||
| │ │ platform-connector │ │ │ | ||
| │ │ - Aggregates health events from both monitors │ │ │ | ||
| │ │ - gRPC transport (ADR-029 TLS) │ │ │ |
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ADR-029 is about slurm drain monitor, and ADR-030 is about TLS but that is between janitor controller and provider.
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Fixed both cross-refs. The monitor→platform-connector hop is actually a node-local Unix domain socket (grpc.insecure_channel("unix://…")), so no TLS applies on that path — I corrected the diagram/text to say that, and clarified that ADR-030's gRPC-TLS decision is the janitor-controller↔janitor-provider connection, which is out of scope here. The stray ADR-029 reference is gone (1b04ea2).
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Confirming this is done at current head (8a5afd0), with one path note since the file moved: the ADR is now docs/designs/050-system-services-monitor-scope.md (renamed from 030 in this PR, because 030 is the gRPC-TLS ADR). The stray ADR-029 reference is gone, and :230-232 states the monitor→platform-connector hop is a node-local Unix domain socket (grpc.insecure_channel("unix://<socket>")) so no TLS applies there, and that ADR-030's decision governs the janitor-controller ↔ janitor-provider path, which is out of scope here. Leaving this open for you to close.
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| ## Context | ||
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| PR #891 adds a `fabric-manager-monitor` with 6 check categories: FM service health, |
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I believe we agreed to split that MR into multiple MR, should we remove the historical context and conversation around that and state the objective problem/gap that we've currently in nvsentinel as the context?
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Done. Rewrote the Context to state the objective gap — nvsentinel has no service-level monitoring of the host daemons behind fabric health (FM up/hung/crashlooping, persistenced, NVSwitch registration state), which sit in a layer neither gpu-health-monitor nor syslog-health-monitor observes. Dropped the PR #891 split narrative entirely (1b04ea2).
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Done at current head (8a5afd0) — and the PR series split you asked for is in place: #1380 (this ADR), #1381 (CI wiring), #1382 (implementation + tests), #1385 (Helm chart), #1383 (demo). The Context section (docs/designs/050-system-services-monitor-scope.md:26-46, renamed from 030 since that number is the gRPC-TLS ADR) now states the objective gap instead of the history: NVSentinel has no service-level monitoring of the host daemons behind fabric health, because gpu-health-monitor observes DCGM device telemetry and syslog-health-monitor parses kernel XID/SXID logs — neither sees systemd unit state, so a hung or crash-looping nvidia-fabricmanager (or NVSwitch registration stuck "In Progress") breaks multi-GPU workloads while every existing check still reports healthy. The #891 split narrative is removed. Leaving this open for you to close.
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@dmvevents this PR has been inactive for 14 days. Do you need help finishing it, or should we close it for now? Feel free to reopen anytime. |
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Actionable comments posted: 6
🤖 Prompt for all review comments with AI agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
Inline comments:
In `@docs/designs/049-system-services-monitor-scope.md`:
- Around line 200-204: Update the monitor-to-platform-connector design to
specify Unix-socket ownership and restrictive permissions, and require
server-side peer or agent authorization before accepting remediation-triggering
HealthEvents. Document and enforce these controls alongside the existing
local-socket transport description, without adding TLS to this hop.
- Around line 154-170: Update the FM readiness definition and
FM_REGISTRATION_STUCK handling to specify a time-based threshold, such as a
configurable registration timeout or consecutive-poll state machine. Treat “In
Progress” as healthy during the allowed startup window, and classify it as stuck
only after the threshold is exceeded, without changing the existing
Completed/Success healthy criteria.
- Around line 318-326: Update the cache reservation, rollback, and commit flow
described in the Concurrency and Rollback sections to be generation-safe: assign
each per-key reservation a token or generation, and only pop on send failure or
commit after success when that token still matches the current reservation.
Preserve newer reservations when older overlapping sends finish, preventing
duplicate transition emissions and stale cache state.
- Around line 137-159: Update the system-services-monitor host-probe flows for
systemctl, journalctl, and nvidia-smi to enforce a timeout on every external
invocation, including separate NRestarts queries and per-GPU checks. Convert
timeout failures into an explicit unknown status with the reason probe-timeout,
and ensure a hung probe cannot block the polling loop or delay other service
checks.
- Around line 308-317: Update CachedEntityState and the event comparison logic
to include a normalized set of errorCode values in the cached condition
identity. Ensure transitions between different error-code combinations emit a
new event even when is_fatal and is_healthy are unchanged, while preserving
order-independent comparison for equivalent code sets.
- Around line 109-118: Update the service-health checks described in
“Service-health signals go to system-services-monitor” to explicitly ignore
absent services: treat systemd LoadState=not-found as not applicable, or
otherwise gate checks on detected platform/service presence, so hosts without
nvidia-fabricmanager or configured GPU-support services do not emit false
*_NOT_RUNNING or GPU_SERVICE_NOT_RUNNING failures.
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Adds the design doc for system-services-monitor — a health-monitor for the host services behind fabric health (nvidia-fabricmanager, nvidia-persistenced, NVSwitch registration state) that sit in a layer neither gpu-health-monitor nor syslog-health-monitor observes today. Numbered 049 (next free slot on main; 030/042/043 taken). Detection mechanism, HealthEvent schema, checkName/errorCode taxonomy, and cached-state semantics are grounded in the system-services-monitor implementation (PR NVIDIA#1382). Signed-off-by: Anton Alexander <dmvevents@users.noreply.github.com>
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Actionable comments posted: 2
🤖 Prompt for all review comments with AI agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
Inline comments:
In `@docs/designs/049-system-services-monitor-scope.md`:
- Around line 161-162: Clarify the boot grace-period behavior so unhealthy
results suppressed during startup do not reserve or commit transition-cache
entries. Ensure the condition is reevaluated when the grace period expires,
allowing a still-unhealthy result to emit as a transition.
- Around line 212-220: Update the system-services monitor event taxonomy table
to define the FM_UNRESPONSIVE contract alongside the existing
FabricManagerServiceDown entries. Add the canonical error code, detection
threshold, and corresponding HealthEvent mapping, ensuring downstream
remediation and deduplication use the unambiguous unresponsive event definition.
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Implements the system-services-monitor package per ADR-030 (NVIDIA#1380): - service_check.py for systemd service health - watcher.py + event_processor.py with thread-safe entity_cache - cli.py with --verbose flag and version handling - logger.py with explicit warning on unknown log levels - Dockerfile (python:3.13 base, apt cache mount per CR review) - Makefile with real lint-test / test / docker-build / docker-publish targets - Unit tests under tests/ covering service_check + event_processor Lands as NVIDIA#891 split (3 of 5) on top of NVIDIA#1380 (ADR) and the CI PR. Excludes cuda_validation.py — that checker is being moved to preflight-checks/cuda-validation/ in a follow-up PR per @XRFXLP review on the umbrella PR. The runtime GPU-allocation concern raised in his review is resolved by removing it from the daemon-poll path entirely. Signed-off-by: Anton Alexander <dmvevents@users.noreply.github.com>
…eview Four behavioral fixes raised by the ADR-049 review (PR NVIDIA#1380): - absent units are not failures: LoadState is now queried alongside ActiveState, and a unit with LoadState=not-found (e.g. a host without nvidia-fabricmanager installed) emits nothing instead of a false, fatal FABRIC_MANAGER_NOT_RUNNING / GPU_SERVICE_NOT_RUNNING - probe failure != service down: a systemctl/nsenter error or timeout means state UNKNOWN; the watcher now logs + counts it instead of emitting a fatal NOT_RUNNING event - FM_REGISTRATION_STUCK is now time-based: 'In Progress' only classifies as stuck after stuck_threshold consecutive polls (default 3, ~90s at the default 30s interval); the streak resets when registration completes. Boot-grace suppression now also applies to fabric-state results, matching the service checks - transition cache: errorCode is part of the cached identity (a code-only escalation like NOT_RUNNING -> NOT_RUNNING+FLAPPING now emits), and rollback is generation-safe (a failed older send no longer pops a newer reservation; object identity is the reservation token) Test suite: 53 passed (9 new tests covering each behavior). Signed-off-by: Anton Alexander <dmvevents@gmail.com>
- specify per-probe timeouts (systemctl 10s, journalctl/nvidia-smi 15s) and the unknown-state rule: a failed/timed-out probe emits no event - add the applicability rule: LoadState=not-found units are skipped, never reported as *_NOT_RUNNING - define the FM_REGISTRATION_STUCK criterion: In Progress for stuck_threshold consecutive polls (default 3), streak resets on completion; boot grace applies to fabric-state checks too - document that boot-grace suppression happens at result generation and cannot poison the transition cache - document socket authorization: root-owned /var/run/nvsentinel hostPath, mounted only into NVSentinel DaemonSets; SO_PEERCRED as a shared platform-connector hardening item - cache identity now includes the normalized errorCode set; rollback is generation-safe (reservation-token semantics) - state explicitly that Phase 1 has no FM_UNRESPONSIVE code and what its future addition requires Matches implementation commit 12f6c07 on PR NVIDIA#1382. Signed-off-by: Anton Alexander <dmvevents@gmail.com>
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Actionable comments posted: 4
🤖 Prompt for all review comments with AI agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
Inline comments:
In `@docs/designs/049-system-services-monitor-scope.md`:
- Around line 231-240: Update the socket authorization section to specify
enforceable socket-file ownership, group, mode, and hostPath mount permissions
for HealthEventOccurredV1 clients. Reference the normative platform-connector
peer-authorization contract and add a requirement/test proving an unauthorized
local client cannot inject remediation-triggering events.
- Around line 377-382: Update the successful-send cache commit described in the
generation-safe rollback flow to validate that the completing reservation still
owns the current reservation token before updating the authoritative last-sent
state. Preserve newer state when an older overlapping send completes later, and
document or specify tests covering both completion orders.
- Around line 374-376: Correct the retry timing description in the Rollback
section so its attempt count, per-attempt deadlines, backoff, and stated
worst-case duration are internally consistent. Prefer documenting a 26-second
total deadline if that matches the intended behavior; otherwise update all
timing values to accurately reflect the actual maximum callback-worker
occupancy.
- Around line 157-162: Update the registration streak logic described in the
design so it resets after every probe result other than "In Progress", including
unknown, N/A, FM_FABRIC_ERROR, and all other non-progress states; only
consecutive "In Progress" polls may count toward FM_REGISTRATION_STUCK.
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- 049 collides with 049-node-validation.md on main; the lowest free number is 050. File renamed and title updated. - Registration streak: reset on EVERY non-'In Progress' result (absent GPU, probe failure, N/A), and not advanced during boot grace. - Socket authorization: stated as enforceable deployment invariants (root:root 0750 dir, non-writable socket, DaemonSet-only mount) a reviewer can verify in the chart, not narrative. - Retry bound corrected: 5 attempts x 10s deadline + exponential sleeps (2s x1.5 cap 15s) = ~66s worst case, not ~26s. - Cache commit is generation-safe on the success path too: commit only if the reservation token still matches, so a slow older send can't overwrite a newer state. Signed-off-by: Anton Alexander <dmvevents@gmail.com>
dmvevents
changed the title
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Inline comments:
In `@docs/designs/050-system-services-monitor-scope.md`:
- Around line 384-397: Define a stable transition ID and enforce per-entity
ordering or stale-generation rejection across HealthEventOccurredV1 and
platform-connector before relying on rollback; ensure timed-out retries and
concurrent older transitions cannot produce duplicate or stale downstream
updates, rather than relying only on local cache reservation tokens.
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Per re-review: the rollback text implied end-to-end guarantees the transport does not provide. The new section states the contract explicitly: delivery is at-least-once (HealthEventOccurredV1 enqueues before returning, so timed-out calls may be accepted AND retried); duplicates are identifiable by a stable dedup key (the entity-cache tuple: nodeName, checkName, sorted entities, normalized codes, fatal/healthy) and harmless to apply since transitions carry absolute state, not increments; per-entity emission order is monotone at the source (serialized callback dispatch, one RPC per cycle) while post-acceptance ordering is a consumer concern (generatedTimestamp + stale-generation rejection). Connector-side enforcement (HealthEvent.id dedup, per-entity sequencing) is called out as a platform-connector- level item shared by all monitors, with this design supplying the inputs it needs — same treatment as the socket peer-auth item. Signed-off-by: Anton Alexander <dmvevents@gmail.com>
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Hey @dmvevents , I was going through the fabric manager related stuff you mentioned and see that a lot of it has been integrated in DCGM health watches in gpu-health-monitor as part of dcgm 4.5.2 support. NVSentinel enables all DCGM health watches in dcgm.py (https://github.com/NVIDIA/NVSentinel/blob/main/health-monitors/gpu-health-monitor/gpu_health_monitor/dcgm_watcher/dcgm.py#L666), maps DCGM_FR_FABRIC_PROBE_STATE in dcgmerrorsmapping.csv https://github.com/NVIDIA/NVSentinel/blob/main/distros/kubernetes/nvsentinel/charts/gpu-health-monitor/files/dcgmerrorsmapping.csv#L126), and uses DCGM 4.5.2 in the GPU health monitor Dockerfile (https://github.com/NVIDIA/NVSentinel/blob/main/health-monitors/gpu-health-monitor/Dockerfile#L15). DCGM’s While I get that the hard dependency is on dcgm 4.5.2 , it works. Do you think, there is still the need for fabric manager changes? |
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Per #891 split (1 of 5). This PR lands ONLY the design doc to provide a stable target for the implementation, CI, Helm chart, and demo PRs to follow.
Splits requested by @XRFXLP in #891 (comment).
What's in this PR
docs/designs/050-system-services-monitor-scope.md— ADR-050 only (design doc, no code)The ADR resolves the two architectural questions raised in #891 review:
gpu-health-monitorvia existingpydcgmpath. Not reimplemented via DCGM exporter HTTP scraping.system-services-monitor(renamed fromfabric-manager-monitor) is scoped to non-DCGM service health — FM systemd state, FM responsiveness, fabric state stuck detection, GPU service lifecycle.Signal ownership table and event taxonomy (FM_DOWN / FM_UNRESPONSIVE / FM_FLAPPING) are in the doc.
Carry-forward from #891
The umbrella PR has accumulated review feedback that maps cleanly to specific split-PRs:
system-services-monitorPython package, ~500-800 LOC)Each subsequent PR will reference back to this one as the scope contract.
cc @XRFXLP @lalitadithya
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