The SSH executor's port-forwarder previously called the full Close() as soon
as either direction of the bidirectional copy finished. Under HTTP-Upgrade
WebSocket traffic this meant: when the WS server flushed its final frame and
shut down the write side, our local->remote io.Copy returned EOF, we closed
the entire SSH channel, the remote->local copy aborted mid-frame, and the
backend's WS reader observed close 1006 (unexpected EOF) instead of a clean
close frame.
Switch to a half-close pattern: each direction CloseWrite()s its destination
when its source EOFs, letting the other half drain the remaining frames. The
final Close happens after both copies return.
The "ssh forwarder dial remote failed: EOF" warning in e2e logs was a
follow-on symptom — the SSH client was being torn down by the abnormal close,
so any later channel-open returned EOF immediately.
José Almeida
b5991a8d82