[script] use systemd service for otbr-agent restart workaround

[yangsong-cnyn]

1. Deleted the original # add calling of link_dongle.py script at startup to update symlink to the dongle misleading comment, as [ncs] bump submodules and update configs #18 has fixed the issue.

2. This implementation creates a dedicated systemd service otbr-agent-restart-workaround.service that runs once after otbr-agent.service has started. This is a more robust and maintainable way to handle service dependencies and startup actions on systemd-based systems.

[gemini-code-assist]

Summary of Changes

Hello @yangsong-cnyn, 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 refactors the otbr-agent restart mechanism from a legacy /etc/rc.local script to a modern systemd service. The change aims to significantly improve the reliability and maintainability of the otbr-agent startup sequence, particularly addressing situations where an nRF dongle might not be immediately available, ensuring the service starts correctly and consistently.

Highlights

• Systemd Service Implementation: Replaced the legacy method of modifying /etc/rc.local with a dedicated systemd service (otbr-agent-restart-workaround.service) to handle the otbr-agent restart workaround.
• Improved Reliability: The new systemd service ensures a more robust, modern, and maintainable approach to restarting otbr-agent, especially in scenarios where the nRF dongle might not be immediately ready at boot.

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[gemini-code-assist]

Code Review

This pull request is a great improvement, replacing the legacy /etc/rc.local mechanism with a modern systemd service for the otbr-agent restart workaround. This makes the setup more robust and maintainable.

I have one suggestion to further improve the robustness of the new systemd service by adding a small delay, which should help ensure the workaround is effective even if the hardware takes a few moments to initialize.

Overall, this is a solid change.

[yangsong-cnyn]

/gemini review

[gemini-code-assist]

Code Review

This pull request modernizes the otbr-agent restart workaround by replacing a legacy /etc/rc.local modification with a dedicated systemd service. This is a significant improvement in terms of reliability and maintainability. My review includes a suggestion to further refine the systemd service unit by using more idiomatic directives, which enhances readability and adheres to systemd best practices. I also noted that the fixed-delay sleep could be made more robust, though the proposed change is already a good step forward.

[gemini-code-assist]

Code Review

This pull request is a great improvement, replacing an outdated and fragile rc.local modification with a modern and robust systemd service to handle the otbr-agent restart workaround. The new approach is more maintainable and reliable. I have one suggestion to further refine the systemd service unit file to make it more idiomatic.

[bukepo]

I don't quite understand the root cause of that issue, and I don't see how this change would improve the reliability.

[yangsong-cnyn]

the original comment is misleading: link_dongle.py is removed as ncs has fixed the USB filename issue.

the PR is 1. removing the misleading comment; 2. using systemd instead of rc

I have updated the PR description

[bukepo]

if the issue is already fixed, so we still need th restart workaround?

[yangsong-cnyn]

I will test and confirm if removing restart otbr-agent is neccesaary