Proposal: Dns support for Dual-Engine

[Flying-Tom]

What type of PR is this?

/kind feature

What this PR does / why we need it:

Implement DNS resolution logic mentioned in #1407

Which issue(s) this PR fixes:
#1407

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

[gemini-code-assist]

Summary of Changes

Hello @Flying-Tom, 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 comprehensive proposal and initial design for enabling DNS resolution capabilities within Kmesh's Dual-Engine mode. The primary goal is to support ServiceEntry configurations that rely on DNS resolution, ensuring seamless migration for users from Istio by leveraging and extending the recently refactored DNS module.

Highlights

• New Design Proposal: A new markdown document (docs/proposal/dual_engine_dns.md) has been added, detailing the motivation, goals, and design specifics for integrating DNS resolution into the Dual-Engine architecture.
• Dual-Engine DNS Support: The PR outlines how to extend the existing DNSResolver to support DNS resolution for workloads originating from ServiceEntry in the Dual-Engine mode, addressing a critical feature gap.
• Asynchronous DNS Handling: The proposal describes the implementation of a WorkloadDnsController that will asynchronously handle DNS resolution requests, decoupling the resolution process from the main workload processing flow.
• Processor Integration: The Processor component will be updated to identify ServiceEntry workloads lacking address information and route them to the new DNS resolution mechanism, including a retry logic for unresolved entries.
• Code Style Enforcement: A minor update to .markdownlint.yml introduces a rule to enforce consistent tab usage in markdown code blocks.

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[Copilot]

Pull Request Overview

This PR introduces a KEP for adding DNS resolution support in Dual-Engine mode and adjusts markdown linting rules.

• Add a detailed proposal document outlining Dual-Engine DNS support
• Update .markdownlint.yml to enforce no-hard-tabs in code blocks

Reviewed Changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 1 comment.

File	Description
docs/proposal/dual_engine_dns.md	New KEP draft for Dual-Engine DNS resolution support
.markdownlint.yml	Added no-hard-tabs rule configuration

Comments suppressed due to low confidence (3)

docs/proposal/dual_engine_dns.md:20

• [nitpick] The Summary section is empty; please provide a concise overview of what this proposal achieves.

### Summary

docs/proposal/dual_engine_dns.md:52

• In the YAML example, the second number: http should likely be name: http to correctly label the port.

    number: http

docs/proposal/dual_engine_dns.md:180

• A for range loop cannot iterate over an integer; consider for i := 0; i < maxRetries; i++ {.

          for range maxRetries {

[gemini-code-assist]

Code Review

The pull request introduces DNS resolution support for the dual-engine mode, enabling seamless migration for users relying on External Name services and DNS resolution typed ServiceEntries. The changes involve refactoring the DNS module, implementing a WorkloadDnsController, and updating the Processor to handle workloads without address information.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 39.23%. Comparing base (716c0d3) to head (bb6fe77).
⚠️ Report is 235 commits behind head on main.
see 99 files with indirect coverage changes

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[fnless]

Are we capturing application DNS resolution requests in this proposal?

[LiZhenCheng9527]

Are we capturing application DNS resolution requests in this proposal?

This proposal does not currently involve the interrcception of DNS resolution request. This proposal is to enable Kmesh to incorporate serviceEntry that resolution is DNS into management.

If you have a need to intercept DNS resolution, can you make a separate issue to explain the exact context?

[Copilot]

Pull Request Overview

Copilot reviewed 3 out of 5 changed files in this pull request and generated 3 comments.

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[Copilot]

Pull Request Overview

Copilot reviewed 2 out of 4 changed files in this pull request and generated 3 comments.

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[Flying-Tom]

cc @LiZhenCheng9527

[LiZhenCheng9527]

/lgtm
/approve

[Flying-Tom]

@LiZhenCheng9527 review request

[LiZhenCheng9527]

/lgtm
/approve

[kmesh-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: LiZhenCheng9527

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• OWNERS [LiZhenCheng9527]

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