Orion Internal Sync: custom http headers

[awgn]

This PR introduces custom HTTP headers, which will be used consistently across the project in upcoming PRs.

[gemini-code-assist]

Summary of Changes

Hello @awgn, 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 introduces a new Rust crate, orion-http-header, designed to centralize and standardize the definition of custom HTTP header names within the project. The primary goal is to ensure consistent usage of these headers across various components, particularly for concerns like tracing, rate-limiting, and proxy-related information. This foundational change prepares the codebase for upcoming features that will rely on these standardized header definitions.

Highlights

• New Crate Creation: A new Rust crate named orion-http-header has been added to the project, serving as a centralized location for defining HTTP header constants.
• Macro for Header Definition: A custom_header! macro has been introduced to streamline the creation of http::HeaderName constants, ensuring consistency and reducing boilerplate when defining new headers.
• Standardized HTTP Header Constants: The new crate defines a set of widely used HTTP header constants, including those for tracing (e.g., B3, Datadog, Traceparent), proxy interactions (e.g., Envoy-specific headers), and custom Orion-specific rate-limiting headers, promoting consistent usage across the project.

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 in your pull request via creating an issue comment (i.e. comment on the pull request page) using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands.

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 issue 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 crate orion-http-header to centralize the definition of custom HTTP headers for the project. The implementation uses a macro to create http::HeaderName constants from static strings, which is efficient and type-safe. My main feedback is to enhance the macro to support documentation comments. This will improve the maintainability and usability of the new crate by allowing each header constant to be documented with its purpose, which is crucial for a shared library.

[hzxuzhonghu]

/lgtm

[hzxuzhonghu]

/approve

[kmesh-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hzxuzhonghu

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Details

Needs approval from an approver in each of these files:

• OWNERS [hzxuzhonghu]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment