fix(icms): create NVCA NATS streams with the HA replica count

[shobham-nv]

TL;DR

icms (deployed as the sis release) created its two NVCA NATS JetStream streams (CreateNvcaFunctionTaskStream, TerminateNvcaStream) with 1 replica, even when the self-managed stack runs in HA mode. If the NATS node holding that single copy went down, the streams went down with it. icms now reads a configured replica count, and the stack passes it the same HA replica count that nvcf-api and invocation-service already get.

Additional Details

• icms.nats.replicas (default 1) is a new property. NatsStreamManager uses it when creating streams.
• For a stream that already exists, icms raises the replica count to the configured value at startup and during its periodic stream validation. It never lowers it, so a stream created under HA keeps its copies if the setting is later turned off. All other settings on the existing stream are left as they are.
• deploy/stacks/self-managed/global.yaml.gotmpl sets ICMS_NATS_REPLICAS on the sis release from nvcf.natsStreamReplicas, the helper already used for NVCF_NATS_REPLICAS and NATS_PROPERTIES__REPLICAS. When HA is off, nothing is set and icms keeps using 1.
• docs/self-managed/high-availability.md now lists icms as a stream creator.
• Follows up on feat(self-managed): self-hosted control-plane high availability #2052.
• Limitation: the stack only picks this up after a new icms image and sis chart are released and the sis chart pin in helmfile.d/02-core.yaml.gotmpl is bumped. That pin is currently 2.4.0.

For the Reviewer

Please look closely at NatsStreamManager.reconcileExistingStream, which does the in-place updateStream.

For QA

• deploy/stacks/self-managed/tests/ha-value-wiring.sh passes. It checks that ICMS_NATS_REPLICAS isn't set when HA is off and is set to "3" when HA is on.
• All NatsStreamManagerTest unit tests pass, including the new raise and no-lower cases. The integration tests need Docker Compose, so CI will run them.
• After release, on an HA cluster, nats stream info CreateNvcaFunctionTaskStream --json | jq '.config.num_replicas' should print 3. The same applies to TerminateNvcaStream.

Issues

NO-REF

Checklist

• I am familiar with the Contributing Guidelines.
• I have signed off my commits for Developer Certificate of Origin (DCO) compliance.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

Summary by CodeRabbit

• New Features
  • NATS streams created by ICMS use a configurable replica count, defaulting to one. Existing streams are raised to the configured count when needed, while preserving their other settings; incompatible configurations are still rejected.
  • Self-managed deployments can configure ICMS stream replicas, and the high-availability guidance covers ICMS-created streams.

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• src/control-plane-services/instance-cluster-management/icms-core/src/main/java/com/nvidia/icms/configuration/nats/NatsConfigurationProperties.java

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📝 Walkthrough

Walkthrough

ICMS now accepts a validated NATS stream replica count and applies it when creating streams or reconciling existing streams. Self-managed deployment values pass the count to SIS when applicable. HA checks and documentation cover this wiring and stream behavior.

Changes

SIS JetStream replicas

Layer / File(s)	Summary
Configurable stream reconciliation src/control-plane-services/instance-cluster-management/icms-core/src/main/java/com/nvidia/icms/configuration/nats/NatsConfigurationProperties.java, src/control-plane-services/instance-cluster-management/icms-core/src/main/java/com/nvidia/icms/outbound/nats/NatsStreamManager.java, src/control-plane-services/instance-cluster-management/icms-core/src/test/java/com/nvidia/icms/outbound/nats/*	The replica count defaults to 1 and must be between 1 and 5. NatsStreamManager applies the configured count when creating streams and raises the replica count of existing streams when it is lower. Tests cover stream creation and reconciliation.
SIS HA replica wiring deploy/stacks/self-managed/global.yaml.gotmpl, deploy/stacks/self-managed/tests/ha-value-wiring.sh, docs/self-managed/high-availability.md	The SIS environment receives ICMS_NATS_REPLICAS when the replica helper returns a value. HA checks cover disabled and preferred modes. The documentation describes SIS stream replication and upgrade behavior.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant NatsStreamManager
  participant NatsConfigurationProperties
  participant JetStream
  NatsStreamManager->>NatsConfigurationProperties: Read configured replica count
  alt Stream does not exist
    NatsStreamManager->>JetStream: Create stream with configured replicas
  else Stream exists or another server creates it
    NatsStreamManager->>JetStream: Fetch existing stream configuration
    JetStream-->>NatsStreamManager: Return existing stream configuration
    NatsStreamManager->>JetStream: Update replicas when below configured count
  end

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Suggested reviewers: apartha-nv

Merge Risk: ⚪ Minimal · up to 3cf6c

ICMS now creates and reconciles its NATS streams with the configured replica count, and an out-of-range value fails fast at startup. I found no remaining merge-blocking risk.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 5.88% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 17 functions across 6 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title follows Conventional Commits format with the required scoped fix type and accurately describes the primary change: configuring NVCA NATS streams with the HA replica count.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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🛡️ CodeQL Analysis

🚨 Found 11 issue(s)

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• 🔵 Notes: 0

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_{🕐 Last updated: 2026-09-30 05:09:23 UTC | Commit: ef64645}

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Inline comments:
Review comments at
@src/control-plane-services/instance-cluster-management/icms-core/src/main/java/com/nvidia/icms/configuration/nats/NatsConfigurationProperties.java:
- Line 38: Validate the NATS replica count before stream initialization by
enabling validation on NatsConfigurationProperties and requiring replicas to be
at least 1. Ensure the configuration properties are validated during binding so
invalid values fail startup immediately rather than reaching
NatsStreamManager.init().

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📥 Commits

Reviewing files that changed from the base of the PR and between 9027d7b and ef64645.

📒 Files selected for processing (8)

• deploy/stacks/self-managed/global.yaml.gotmpl
• deploy/stacks/self-managed/tests/ha-value-wiring.sh
• docs/self-managed/high-availability.md
• src/control-plane-services/instance-cluster-management/icms-core/src/main/java/com/nvidia/icms/configuration/nats/NatsConfigurationProperties.java
• src/control-plane-services/instance-cluster-management/icms-core/src/main/java/com/nvidia/icms/outbound/nats/NatsStreamManager.java
• src/control-plane-services/instance-cluster-management/icms-core/src/test/java/com/nvidia/icms/outbound/nats/NatsMessageSenderClientIntegrationTest.java
• src/control-plane-services/instance-cluster-management/icms-core/src/test/java/com/nvidia/icms/outbound/nats/NatsStreamManagerIntegrationTest.java
• src/control-plane-services/instance-cluster-management/icms-core/src/test/java/com/nvidia/icms/outbound/nats/NatsStreamManagerTest.java

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[apartha-nv]

lgtm

[balajinvda]

🎉 This PR is included in src/control-plane-services/instance-cluster-management/v0.8.3 🎉

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