hack/util.sh: auto-detect macOS host IP instead of interactive prompt

[Krishiv-Mahajan]

What type of PR is this?
/kind bug

What this PR does / why we need it:
The util::get_macos_ipaddress function in hack/util.sh unconditionally calls read to wait for user input, even when a valid IP was already auto-detected. This causes hack/local-up-karmada.sh to hang indefinitely in any non-interactive environment (CI pipelines, GitHub Actions, background scripts).

Additionally, the detection was hardcoded to en0 (WiFi only), which silently fails for developers on USB Ethernet, Thunderbolt, or VPN — resulting in an empty HOST_IPADDRESS and member clusters unable to reach the control plane.

This PR replaces the interactive prompt with a layered auto-detection approach:
If MAC_NIC_IPADDRESS is already set (e.g. by CI), use it directly
Detect the active interface via route get default instead of hardcoding en0
If the default route interface has no IP (VPN tunnel), scan en0–en3
Fall back to 127.0.0.1 with a clear warning if all detection fails

Which issue(s) this PR fixes:
Fixes #7257
Part of #7269

Special notes for your reviewer:
Tested end-to-end on macOS 14.3 (Apple Silicon) — ./hack/local-up-karmada.sh completed without any user input and all three member clusters reached Ready status. Linux and WSL2 code paths are unaffected (change is inside the existing darwin guard).

Does this PR introduce a user-facing change?:
hack/util.sh: Fixed util::get_macos_ipaddress hanging for user input on macOS by replacing the interactive prompt with layered auto-detection from the active network interface, enabling non-interactive and CI usage.

[karmada-bot]

Welcome @Krishiv-Mahajan! It looks like this is your first PR to karmada-io/karmada 🎉

[gemini-code-assist]

Summary of Changes

Hello, 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 significantly enhances the hack/util.sh script by overhauling the macOS IP address detection mechanism. The primary goal is to eliminate the need for interactive user input during Karmada setup on macOS, thereby enabling seamless execution in automated environments like CI/CD pipelines. The changes introduce a more intelligent and layered approach to identifying the host IP, ensuring greater compatibility across various network configurations and improving the overall reliability of the setup process.

Highlights

• Non-interactive macOS IP detection: The util::get_macos_ipaddress function no longer requires user input, resolving issues where hack/local-up-karmada.sh would hang indefinitely in non-interactive environments like CI pipelines.
• Enhanced IP address auto-detection: The detection logic now prioritizes a pre-set MAC_NIC_IPADDRESS environment variable, then identifies the active network interface via the routing table, and falls back to scanning common physical interfaces (en0-en3) if the default route has no IP.
• Improved network interface compatibility: The previous hardcoded reliance on en0 has been removed, allowing correct IP detection for users on USB Ethernet, Thunderbolt, or VPN connections.
• Robust fallback mechanism: If all auto-detection methods fail to find a routable IP, the function now defaults to 127.0.0.1 and provides a clear warning to the user.

Changelog

• hack/util.sh
  • Corrected a typo in a comment for the util::wait_pod_ready function.
  • Replaced the interactive prompt-based macOS IP address detection with an automated, multi-stage detection logic within util::get_macos_ipaddress.
  • Updated the MAC_NIC_IPADDRESS initialization to support pre-setting the variable.
  • Introduced logic to detect the active interface via route get default.
  • Added a fallback loop to scan en0 through en3 if the default interface lacks an IP.
  • Implemented a final fallback to 127.0.0.1 with a warning if no routable IP is found.

Activity

• No human activity (comments, reviews, approvals) has been recorded for this pull request yet.

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[karmada-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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Details

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• hack/OWNERS

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[gemini-code-assist]

Code Review

This pull request significantly improves the user experience for macOS users by replacing an interactive prompt for the host IP address with a robust, layered auto-detection mechanism in hack/util.sh. The new logic correctly handles various network configurations, including the use of an existing environment variable, detection of the active network interface, and sensible fallbacks. This change makes the scripts non-interactive, which is a great enhancement for CI/CD pipelines and automated setups. The implementation is clean and well-commented. The only minor issue found was a typo in a comment, which has been noted for correction.

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 42.00%. Comparing base (105c6ef) to head (57cb736).
⚠️ Report is 18 commits behind head on master.
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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7267      +/-   ##
==========================================
+ Coverage   41.99%   42.00%   +0.01%     
==========================================
  Files         874      874              
  Lines       53542    53539       -3     
==========================================
+ Hits        22483    22490       +7     
+ Misses      29372    29364       -8     
+ Partials     1687     1685       -2     

Flag	Coverage Δ
unittests	42.00% <ø> (+0.01%)	⬆️

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[Copilot]

Pull request overview

Updates the macOS host IP discovery in hack/util.sh to avoid interactive prompts and better handle non-en0 interfaces, preventing hack/local-up-karmada.sh from hanging in non-interactive environments.

Changes:

• Remove interactive read prompt from util::get_macos_ipaddress and use layered auto-detection instead.
• Detect the default-route interface IP (via route get default) and fall back to scanning en0–en3.
• Add a last-resort fallback behavior when no IP can be detected.

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