feat: support smooth upgrade with checking csi sock

[imeoer]

When the model CSI driver is deployed as a DaemonSet pod, newly created pod may delete the sock file that the old pod was listening on. If the new pod hasn't started properly yet, this causes a period of service unavailability.

This change adds a check to verify if the sock file exists and is listening, if it is, the new pod will exit with an error.

[gemini-code-assist]

Summary of Changes

Hello @imeoer, 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 robustness of CSI driver upgrades, particularly when deployed as a DaemonSet. It addresses a potential service unavailability issue that could arise if a newly created pod prematurely deletes the active socket of an old pod. By implementing a pre-startup check for an already listening CSI socket, the changes ensure that a new pod will not start and disrupt an active service, thereby facilitating smoother and more reliable upgrades.

Highlights

• New isSockListening function: Introduced a utility function isSockListening in pkg/server/server.go that checks if a given Unix socket path exists and is actively listening for connections within a specified timeout.
• Pre-startup CSI Socket Check: Modified the Server.Run method to include a check for an already listening CSI socket. If the server is in node mode and an active CSI socket is detected at the configured endpoint, the new server instance will exit with an error, preventing it from interfering with an existing, active CSI driver.

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[gemini-code-assist]

Code Review

This pull request introduces a check to prevent service disruption during upgrades of the CSI driver. A new function isSockListening is added to verify if a Unix socket is already in use. This check is integrated into the server's startup sequence to exit early if another pod is already listening on the CSI socket. The overall approach is sound and addresses the problem described. I've added a couple of comments with suggestions to improve code clarity and robustness by handling a potential error and removing a magic number.

[aftersnow]

lgtm

[chlins]

lgtm