fix(websocket_server sink): release listener and connections on shutdown

[U-S-jun]

Summary

Removing a websocket_server sink during a configuration reload leaves its listener and client tasks running. Re-adding the sink on the same address can then fail to bind and shut down Vector.

This change keeps those tasks owned by the sink:

• Close the listener and cancel pending TLS/WebSocket handshakes.
• Give established connections one shared five-second grace period to drain queued messages, send a Going Away (1001) close frame, and wait for the peer's close response.
• Abort and join remaining connection tasks before normal sink shutdown completes.
• Abort owned tasks asynchronously if the sink future is dropped.

The sink also declares its TCP resource so same-address replacement waits for the previous sink to finish. Global reload logging and exit-code behavior are unchanged.

References

• Closes: websocket_server sink leaks its listener and fatally crashes Vector on reload when the address is reused #26442

Vector configuration

sources:
  http_in:
    type: http_server
    address: 127.0.0.1:18082
    decoding:
      codec: json

sinks:
  discard:
    type: blackhole
    inputs: [http_in]
  live_logs:
    type: websocket_server
    inputs: [http_in]
    address: 127.0.0.1:18081
    encoding:
      codec: json

Remove and re-add live_logs, sending SIGHUP after each configuration change.

How did you test this PR?

Validated in Linux containers using Rust 1.96.1.

make test FEATURES=sinks-blackhole,sinks-websocket_server,sources-http_server \
  SCOPE="--lib -E 'test(websocket_server)'"

make check-clippy FEATURES=sinks-blackhole,sinks-websocket_server,sources-http_server

make fmt
make check-fmt
make check-markdown
make check-changelog-fragments

All 24 targeted tests passed, including resource conflicts, same-port replacement, pending handshakes, queued-message draining, sink cancellation, and the shared shutdown deadline.

Additional process-level checks:

• Three remove/re-add cycles each with plaintext and TLS connections, verifying socket cleanup and port reuse.
• Going Away close frames and forced cleanup of unresponsive clients after the shared grace period.
• Injected file-descriptor exhaustion (EMFILE), verifying that existing WebSocket clients still receive events after accepting new connections stops.

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the no-changelog label to this PR.

Added changelog.d/26442_websocket_server_shutdown.fix.md.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-10T08:58:00.812836Z	173ebee	New commits

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[U-S-jun]

I have read the CLA Document and I hereby sign the CLA