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fix(grpc-proxy): stop liveness from depending on nvcf-api - #2902
grpc-proxy used one /health for liveness and readiness, and it checked
nvcf-api. An nvcf-api outage restarted every grpc-proxy pod and cut running
gRPC streams. Liveness now checks the process only; readiness checks only the
pod's NATS connection.
Additional Details
/health on the client port checks NATS only. Liveness uses the admin :10083/health.
The NATS client reconnects without a limit. It used to stop after 60
attempts, which left the pod unready for good after a long NATS outage.
CI runs deploy/helm/grpc-proxy/tests/probes_test.sh.
The invocation-service and vanity-gateway parts of this change moved to
their own PRs (see Related Pull Requests).
Measured on a k3d stack:
Before
After
nvcf-api down 3 min: restarts
every grpc-proxy pod
0
nvcf-api down 3 min: open gRPC stream
cut at 23 s
no failures
NATS down 4 min
unready until restarted
ready 13 s after NATS returned
New calls still fail while nvcf-api is down; they need it to authorize the
caller.
For the Reviewer
proxy/health.go, proxy/invocation/nats.go
Chart probe values in deploy/helm/grpc-proxy/grpc-proxy/values.yaml
For QA
New tests: grpc-proxy /health and NATS option tests, chart probe test.
QA needed: HA case for losing both nvcf-api replicas.
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Walkthrough
Readiness checks for grpc-proxy and HTTP invocation now use pod-local NATS health instead of NVCF API health. Helm charts configure process-level liveness probes and retain service-level readiness probes. grpc-proxy also configures unlimited NATS reconnects.
grpc-proxy and HTTP invocation readiness checks use NATS health rather than NVCF API health. HTTP invocation removes its NVCF health client and cache. Tests cover NATS failures and /health responses while the NVCF API is unhealthy.
Liveness and readiness probe configuration deploy/helm/grpc-proxy/..., deploy/helm/http-invocation/..., deploy/helm/vanity-gateway/..., src/invocation-plane-services/vanity-gateway/{README.md,gateway/health.go}, .github/workflows/build-test.yml
grpc-proxy liveness uses metrics /health; HTTP invocation liveness uses /info; vanity-gateway liveness uses admin /health. Readiness retains the client or HTTP endpoint. Chart-render tests verify probe settings, and CI runs the three chart probe tests.
NVIDIA/nvcf#2896: Changes overlapping service health checks and liveness probes, and adds chart probe tests.
Suggested reviewers:balajinvda
Merge Risk: Minimal · previous review 41b7e
No concrete CI or probe-coverage failure is established by this change.
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The title follows Conventional Commits with the required customer-impact scope and accurately describes the primary bug fix: removing the nvcf-api dependency from liveness checks.
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Actionable comments posted: 1
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Inline comments:
Review comments at @src/invocation-plane-services/vanity-gateway/README.md:
- Line 640: Update the readiness documentation sentence in the README to specify
that an `nvcf api` outage removes pods from the Service, distinguishing it from
an LLM Gateway-only outage; preserve the statement that this does not restart
the pods.
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With NATS out of liveness, what restarts a pod whose NATS connection gives up? nats.Connect uses the default 60 reconnects, so after a few minutes of NATS being down the conn goes CLOSED for good. Readiness stays down and liveness passes, so every replica stays out of the Service until someone restarts them. Could we set nats.MaxReconnects(-1), or fail liveness only when the status is CLOSED?
rohithb-hub
changed the title
fix(health): stop data-plane liveness probes from depending on nvcf-api
fix(grpc-proxy): stop liveness from depending on nvcf-api
Oct 30, 2026
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Reviewed with the James McNamee review skill at fdbe994. Two P1 findings and one P2 finding are inline; withholding approval.
The liveness separation is useful. An initialized gRPC session reuses its worker connection for subsequent RPCs without another NVCF API authorization call, so restarting the proxy during an API outage destroys work that can otherwise continue. Unlimited NATS reconnects are also necessary once liveness stops checking NATS, but the current implementation still has a terminal authentication-failure path, and the chart defaults to an older image without the reconnect change.
The readiness change deserves separate evidence. Removing a ready endpoint does not by itself establish that an already connected stream will be terminated. The reported before/after result changes both probes together. Please compare liveness-only against this PR using an outside-in scenario that both preserves an established stream and delays the worker CONNECT until after the API outage has made the old readiness probe fail. Also exercise a new session requiring authorization, recovery after restoring the API, and a transient NATS authentication failure. Keep BDD as a thin wrapper around actual requests and deployment operations.
Validation: direct Go tests passed for ./proxy and ./proxy/invocation with Go 1.26.10; the chart probe test passed for Deployment and DaemonSet. A local NATS-protocol fixture using the PR's actual NewNatsConnection reproduced CLOSED after two reconnect authorization failures despite MaxReconnect=-1; an IgnoreAuthErrorAbort control reconnected. Bazel's source query confirmed health_test.go is omitted from proxy_test. No live Kubernetes outage or HA validation was run.
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[P1] Handle terminal authentication failures after removing the restart fallback
MaxReconnects(-1) does not keep this connection retrying after repeated authentication failures. The pinned nats.go client aborts reconnect after the same auth error occurs twice unless IgnoreAuthErrorAbort is enabled. A transient OAuth/auth-callout failure during reconnect can therefore leave nc permanently CLOSED. Readiness then remains 503, while the new admin-port liveness probe stays healthy, so the pod never recovers after authentication is restored.
I reproduced this using this PR's actual NewNatsConnection against a local protocol fixture: an initial successful connection followed by two rejected reconnects produced status=CLOSED with MaxReconnect=-1. A control with nats.IgnoreAuthErrorAbort() reconnected when the fixture accepted the next attempt. See the upstream option contract.
Keep retrying through these transient auth failures, or explicitly recover/restart on a terminal CLOSED connection. Add a disconnect/reject/recover test; checking the MaxReconnect option alone misses this failure.
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[P1] Ship a compatible image before switching the liveness probe
This chart still defaults grpcproxy.image.tag to 1.35.0. Rendering it produces the new admin-port liveness probe with that old image, whose NATS client still uses the default 60 reconnect attempts (verified in the service's v1.35.0 source tag). After a sufficiently long NATS outage that connection becomes permanently CLOSED; with this probe change Kubernetes no longer restarts the pod, so it remains unready even after NATS recovers.
The Go change in this PR does not alter the image selected by the chart. Release automation opens a separate reviewed image-pin PR, so the safe pairing is not present in this chart revision. Release the reconnect fix first, then enable this probe with the corresponding published image pin, or otherwise prevent this incompatible chart/image combination from being shipped.
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[P2] Include the new health test in the Bazel target
proxy/BUILD.bazel explicitly lists the source files for proxy_test, but health_test.go is absent. The grpc-proxy CI lane runs the Bazel suite, so this regression test is silently omitted even though direct go test runs it. I confirmed the omission with bazel query 'labels(srcs, //src/invocation-plane-services/grpc-proxy/proxy:proxy_test)'. Add this file to the target and add its direct nats_go test dependency so the readiness regression is exercised by the canonical CI path.
Concrete live-test proposal, following the inline review:
Use a fresh, isolated self-managed stack with real Gateway routing, two grpc-proxy replicas, two NVCF API replicas, and a deployed gRPC echo function. The existing Load Tester Supreme BDD scenario provides the deployment setup. Its Echo/EchoMessageStreaming method supports repeats and a per-reply delay, so a request such as {"message":"outage-smoke","repeats":300,"delay":1} provides a five-minute stream. Set client deadlines above the experiment duration. Route through the normal gRPC endpoint; do not use port-forwarding for invocation traffic.
Compare these variants with the same function, client, topology, and outage timing:
Variant
Liveness
Readiness
NATS recovery
Released baseline
Existing client-port check
Existing API + NATS check
Released behavior
Liveness-only candidate
Admin process check
Retain API + NATS check
Include the proposed reconnect fixes
Full candidate
Admin process check
NATS only
Same reconnect fixes as liveness-only
The two candidates should differ only in the API readiness check. This isolates the readiness decision from the restart and reconnect fixes.
API outage during an established stream. Wait for the first reply, take both API replicas down for three minutes, and restore their original replica count. For both candidates, require the same uninterrupted stream to deliver all expected replies with no proxy restart or client reconnect. Separately verify that a new session on a fresh client connection fails during the outage and succeeds after recovery. Existing-session RPCs can reuse authorization, so they are not a valid negative authorization test.
Worker callback after readiness would have failed. In a separate run, use a temporary, test-scoped network gate to hold a new worker CONNECT after authorization/work enqueue. Take the API down, wait until the liveness-only candidate is actually unready, then release the gate within the configured client/worker deadlines. Compare successful completion through the real callback route. Record the result for both candidates rather than assuming endpoint removal kills an established connection. This is the key evidence for removing the readiness dependency.
Long NATS outage. Make all configured NATS endpoints unavailable long enough to exhaust the old retry budget in the baseline; four minutes is not necessarily sufficient with multiple server URLs. Restore NATS without restarting proxy pods. Require both corrected candidates to reconnect, become ready, and serve a fresh invocation within a declared recovery deadline. This case tests recovery; it does not assume existing worker sessions survive loss of NATS.
Transient NATS authentication rejection. Run with the proxy actually using the OAuth/auth-callout path. Temporarily make that auth dependency unavailable and force its existing NATS connection to reconnect, without restarting the proxy. Confirm at least two consecutive server-side authentication rejections, then restore auth. Require automatic reconnection, readiness, and a successful fresh invocation with the same proxy pod UID and restart count. If the injected fault only produces TCP timeouts, this case has not exercised the reported auth-abort bug.
Released chart/image pairing. Run the long-outage case with the exact image selected by the rendered chart, not just a locally built candidate. The present default is 1.35.0, which lacks the reconnect fix. Repeat after the compatible image pin lands so the installable artifact, not only the source build, demonstrates recovery.
Capture rendered probes, actual image digests, pod UIDs/restart counts, readiness transitions, NATS reconnect/auth-error logs, client reply counts/statuses, and recovery timestamps. Exercise each proxy replica. Restore recorded replica counts and test-scoped fault rules after each case, including failed runs.
BDD should remain a thin wrapper around CLI requests, explicit deployment/fault operations, and observable results. Do not add authorization rules or dependency-health decisions to the test harness. This is a proposed live run; I have not injected faults into a cluster.
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sbaum1994
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TL;DR
grpc-proxy used one
/healthfor liveness and readiness, and it checkednvcf-api. An nvcf-api outage restarted every grpc-proxy pod and cut running
gRPC streams. Liveness now checks the process only; readiness checks only the
pod's NATS connection.
Additional Details
/healthon the client port checks NATS only. Liveness uses the admin:10083/health.attempts, which left the pod unready for good after a long NATS outage.
deploy/helm/grpc-proxy/tests/probes_test.sh.their own PRs (see Related Pull Requests).
Measured on a k3d stack:
New calls still fail while nvcf-api is down; they need it to authorize the
caller.
For the Reviewer
proxy/health.go,proxy/invocation/nats.godeploy/helm/grpc-proxy/grpc-proxy/values.yamlFor QA
/healthand NATS option tests, chart probe test.Related Pull Requests
Issues
Relates to #1524
Checklist
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