refactor: make hostnames more descriptive and simplify dns check command

[Monokaix]

Overview:

make hostnames more descriptive and simplify dns check command

Details:

Changes:

1. The hostnames var in mpirun -H command both include leader/worker pods, so it's more suitable to use all hostnames instead of only worker, or it will cause some misunderstanding
2. The dns ready check should exclude leader pod itself and only check worker pods is enough, which is simpler and more efficient

Where should the reviewer start?

based on: #4477

Related Issues: (use one of the action keywords Closes / Fixes / Resolves / Relates to)

• closes GitHub issue: #xxx

Summary by CodeRabbit

• Refactor

  • Improved internal hostname handling in the deployment backend to enhance multinode configuration support and deployment orchestration reliability.

• Tests

  • Updated test suite to validate the refactored hostname generation logic.

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[github-actions]

👋 Hi Monokaix! Thank you for contributing to ai-dynamo/dynamo.

Just a reminder: The NVIDIA Test Github Validation CI runs an essential subset of the testing framework to quickly catch errors.Your PR reviewers may elect to test the changes comprehensively before approving your changes.

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[coderabbitai]

Walkthrough

The PR refactors hostname generation in the TRTLLM backend, replacing a comma-separated string return type with a string slice return type. The function generateWorkerHostnames is renamed to hostNamesList, with callers updated to join the slice when needed for MPI configuration and DNS-wait logic in multinode deployments.

Changes

Cohort / File(s)	Summary
Hostname generation refactoring deploy/cloud/operator/internal/dynamo/backend_trtllm.go	Function generateWorkerHostnames replaced with hostNamesList returning []string instead of string. MPI host string now constructed via strings.Join(hostNamesList, ","). DNS-wait logic updated to use hostNamesList[1:] for worker list construction.
Test updates deploy/cloud/operator/internal/dynamo/backend_trtllm_test.go	Test renamed to TestTRTLLMBackend_hostNamesList. Verification switched from substring containment checks to exact list equality using reflect.DeepEqual on the returned slice.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

• Verify that all call sites of hostNamesList properly handle the slice return type and join as needed
• Confirm hostNamesList[1:] slicing logic in DNS-wait path is correct for multinode scenarios
• Ensure test expectations align with refactored function behavior

Poem

A rabbit once tangled with strings all askew,
But slices of hostnames made jobs shiny new,
With join and with slice, the addresses unite,
MPI marches onward, the deployment's quite right! 🐰

Pre-merge checks

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description check	✅ Passed	The description covers all required template sections with specific details about the rationale and changes, though the related issue section remains as a placeholder.
Title check	✅ Passed	The PR title accurately describes the main refactoring changes: making hostnames more descriptive (using all hostnames instead of just worker hostnames) and simplifying the DNS check command (excluding leader and checking only workers).

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