tests for the same socket in Device Plugin - #139338

…ubstrate#3486)

Follow-up to agent-substrate#3323, as @SergeyKanzhelev suggested there. kubelet expects
a device plugin to switch to a new socket when it re-registers. Since
1.37 it rejects a Register for a socket it still has connected, and two
overlapping Registers for one socket can wedge the resource as "already
connected" until kubelet restarts:
kubernetes/kubernetes#139338

- the device plugin listens on a new `ate.dev-kvm-<random>.sock` for
each registration, and removes sockets left over from earlier atelets
- the device plugin stays up until atelet exits again. agent-substrate#3323 stopped it
on SIGTERM to avoid overlapping with the replacement pod, but the
DaemonSet only starts the replacement once the old pod is gone, so that
just left `ate.dev/kvm` unhealthy for the whole drain

<!-- e.g. "AI-assisted, I reviewed and tested it." No AI co-author
trailers. -->
AI use: I used Claude to draft this and reviewed it.

<!-- Breaking change? Describe what users must do on upgrade and ask for
the `breaking-change` label. -->

- [x] Tests pass
- [x] Docs updated

---------

Signed-off-by: Benjamin Elder <[email protected]>
(cherry picked from commit 38e9ef6)
Signed-off-by: Eitan Yarmush <[email protected]>

…ubstrate#3486)

Follow-up to agent-substrate#3323, as @SergeyKanzhelev suggested there. kubelet expects
a device plugin to switch to a new socket when it re-registers. Since
1.37 it rejects a Register for a socket it still has connected, and two
overlapping Registers for one socket can wedge the resource as "already
connected" until kubelet restarts:
kubernetes/kubernetes#139338

- the device plugin listens on a new `ate.dev-kvm-<random>.sock` for
each registration, and removes sockets left over from earlier atelets
- the device plugin stays up until atelet exits again. agent-substrate#3323 stopped it
on SIGTERM to avoid overlapping with the replacement pod, but the
DaemonSet only starts the replacement once the old pod is gone, so that
just left `ate.dev/kvm` unhealthy for the whole drain

<!-- e.g. "AI-assisted, I reviewed and tested it." No AI co-author
trailers. -->
AI use: I used Claude to draft this and reviewed it.

<!-- Breaking change? Describe what users must do on upgrade and ask for
the `breaking-change` label. -->

- [x] Tests pass
- [x] Docs updated

---------

Signed-off-by: Benjamin Elder <[email protected]>

Follow-up to #3323, as @SergeyKanzhelev suggested there. kubelet expects
a device plugin to switch to a new socket when it re-registers. Since
1.37 it rejects a Register for a socket it still has connected, and two
overlapping Registers for one socket can wedge the resource as "already
connected" until kubelet restarts:
kubernetes/kubernetes#139338

- the device plugin listens on a new `ate.dev-kvm-<random>.sock` for
each registration, and removes sockets left over from earlier atelets
- the device plugin stays up until atelet exits again. #3323 stopped it
on SIGTERM to avoid overlapping with the replacement pod, but the
DaemonSet only starts the replacement once the old pod is gone, so that
just left `ate.dev/kvm` unhealthy for the whole drain

<!-- e.g. "AI-assisted, I reviewed and tested it." No AI co-author
trailers. -->
AI use: I used Claude to draft this and reviewed it.

<!-- Breaking change? Describe what users must do on upgrade and ask for
the `breaking-change` label. -->

- [x] Tests pass
- [x] Docs updated

---------

Signed-off-by: Benjamin Elder <[email protected]>
(cherry picked from commit 38e9ef6)
Signed-off-by: Eitan Yarmush <[email protected]>