[Feat] allow annotation on router pod

[NargiT]

Some feature in istio are applied on Pod resource. This PR aim to add this feature so it easier to configure.

• Make sure the code changes pass the pre-commit checks.
• Sign-off your commit by using -s when doing git commit
• Try to classify PRs for easy understanding of the type of changes, such as [Bugfix], [Feat], and [CI].

Detailed Checklist (Click to Expand)

Thank you for your contribution to production-stack! Before submitting the pull request, please ensure the PR meets the following criteria. This helps us maintain the code quality and improve the efficiency of the review process.

PR Title and Classification

Please try to classify PRs for easy understanding of the type of changes. The PR title is prefixed appropriately to indicate the type of change. Please use one of the following:

• [Bugfix] for bug fixes.
• [CI/Build] for build or continuous integration improvements.
• [Doc] for documentation fixes and improvements.
• [Feat] for new features in the cluster (e.g., autoscaling, disaggregated prefill, etc.).
• [Router] for changes to the vllm_router (e.g., routing algorithm, router observability, etc.).
• [Misc] for PRs that do not fit the above categories. Please use this sparingly.

Note: If the PR spans more than one category, please include all relevant prefixes.

Code Quality

The PR need to meet the following code quality standards:

• Pass all linter checks. Please use pre-commit to format your code. See README.md for installation.
• The code need to be well-documented to ensure future contributors can easily understand the code.
• Please include sufficient tests to ensure the change is stay correct and robust. This includes both unit tests and integration tests.

DCO and Signed-off-by

When contributing changes to this project, you must agree to the DCO. Commits must include a Signed-off-by: header which certifies agreement with the terms of the DCO.

Using -s with git commit will automatically add this header.

What to Expect for the Reviews

We aim to address all PRs in a timely manner. If no one reviews your PR within 5 days, please @-mention one of YuhanLiu11
, Shaoting-Feng or ApostaC.

[gemini-code-assist]

Summary of Changes

Hello @NargiT, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the Helm chart for the router component by enabling the configuration of custom annotations directly on the router pods. This provides increased flexibility for users to integrate the router with other systems, such as Istio, which rely on pod-level annotations for specific feature activation or configuration.

Highlights

• Router Pod Annotations: This pull request introduces the ability to specify custom annotations for the router pods deployed via the Helm chart.
• Helm Chart Configuration: A new "podAnnotations" field has been added under "routerSpec" in the Helm chart's "values.yaml" to allow users to define these annotations.
• Schema Validation: The "values.schema.json" has been updated to include the "routerSpec.podAnnotations" field, ensuring proper validation for the new configuration option.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

This pull request introduces a new feature to allow specifying annotations for the router pod, which is useful for integration with service meshes like Istio. The changes correctly update the values.schema.json and deployment-router.yaml. However, there is an indentation issue in the Helm template for the router deployment that would result in invalid YAML. I've provided a comment with a suggested fix to correct the indentation.

[Copilot]

Pull Request Overview

This PR adds support for pod annotations in the router deployment configuration. This allows users to specify custom annotations for router pods via the Helm values.

• Added podAnnotations field to the routerSpec schema
• Implemented pod annotations rendering in the router deployment template

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
helm/values.schema.json	Added podAnnotations property to routerSpec schema definition
helm/templates/deployment-router.yaml	Added template logic to render pod annotations in router deployment
helm/templates/_helpers.tpl	Added blank line (whitespace only change)

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[zerofishnoodles]

Does service need annotation under some conditions too? If there is a possibility, would it be better to make this annotation more general to service too?