daemon: fix kernel argument management and logging errors

[rollandf]

This commit addresses several issues in the sriov-network-config-daemon relating to host configuration management and observability.

1. Fix kargs.sh for read-only root filesystems: The daemon now uses the host's /tmp directory (via chroot) for temporary workspace files. This allows the script to function correctly when the container is deployed with 'readOnlyRootFilesystem: true', which previously caused 'cp' and 'grep' failures.

2. Fix logging serialization bug: Updated NodeReconciler to correctly call the Name() method of the main plugin when logging errors. Previously, passing the function pointer directly caused "json: unsupported type: func() string" errors, masking the actual reconciliation failures.

[github-actions]

Thanks for your PR,
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To skip the vendors CIs, Maintainers can use one of:

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  Best regards.

[greptile-apps]

Greptile Summary

Fixed two critical bugs in the SR-IOV network config daemon: (1) kernel argument management now works with read-only container filesystems by using the host's /tmp directory via chroot mktemp, and (2) logging serialization errors resolved by calling Name() method instead of passing the function pointer.

• Modified kargs.sh to create temporary files in host filesystem instead of container root
• Added proper cleanup of temporary files on all exit paths including error cases
• Fixed JSON marshaling error in daemon.go by invoking the Name() method to get string value
• Both changes are minimal, focused fixes that address specific runtime failures

Confidence Score: 5/5

• Safe to merge - both fixes address specific, well-understood bugs with minimal, correct changes
• The changes are straightforward bug fixes with clear benefits: the kargs.sh change enables operation with read-only root filesystems (a security best practice), and the daemon.go change fixes a logging bug that was masking actual errors. Both fixes are minimal and targeted, with no architectural changes or risky refactoring
• No files require special attention

Important Files Changed

Filename	Overview
bindata/scripts/kargs.sh	Fixed read-only filesystem issue by using host's /tmp via mktemp instead of container's /tmp, with proper cleanup on all paths
pkg/daemon/daemon.go	Fixed JSON serialization bug by calling Name() method instead of passing function pointer for logging

Sequence Diagram

sequenceDiagram
    participant Daemon as sriov-config-daemon
    participant Container as Container FS
    participant Host as Host FS (chroot)
    participant Logger as Error Logger
    participant Plugin as VendorPlugin

    Note over Daemon,Plugin: Scenario 1: Kernel Args Management (kargs.sh)
    
    Daemon->>Container: Check if container root is read-only
    Container-->>Daemon: readOnlyRootFilesystem: true
    
    Daemon->>Host: chroot mktemp (create temp file in host /tmp)
    Host-->>Daemon: /tmp/tmp.XXXXXX
    
    Daemon->>Daemon: Map host path to container: /host/tmp/tmp.XXXXXX
    Daemon->>Host: cp /etc/default/grub to temp file
    
    Daemon->>Daemon: Modify kernel args in temp file
    
    alt Changes detected
        Daemon->>Host: cp temp file back to /etc/default/grub
        Daemon->>Host: chroot update-grub
        Host-->>Daemon: grub updated
    end
    
    Daemon->>Daemon: rm -f temp file (cleanup)
    
    Note over Daemon,Plugin: Scenario 2: Logging Fix (daemon.go)
    
    Daemon->>Plugin: OnNodeStateChange(desiredState)
    Plugin-->>Daemon: error occurred
    
    Daemon->>Logger: funcLog.Error(err, mainPluginName: dn.mainPlugin.Name())
    Note over Logger: Before: passed dn.mainPlugin.Name (func pointer)<br/>After: passed dn.mainPlugin.Name() (string result)
    Logger-->>Daemon: Successfully logged error with plugin name

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