feat: multi-session terminal backend core (PR 1)
- Add TerminalSessionModel DB table with instance_id FK, name, status, created_at, last_activity_at, closed_at columns - Add Alembic migration for terminal_sessions table - Refactor TerminalManager to use composite key (instance_id, session_id) supporting up to 5 concurrent sessions per instance - Add create_session, get_session, get_sessions_for_instance, close_session - Preserve get_or_create_session for backward compatibility (default session) - Fix attach_websocket to only close sockets within same session - Add name (auto-generated 'Session N') and status tracking to TerminalSession - Add 7 unit tests for multi-session logic Quality gates: pytest (7 new passed, 174 total passed, 51 pre-existing failures)
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@@ -18,18 +18,28 @@ logger = logging.getLogger(__name__)
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class TerminalSession:
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"""Manages a single terminal session connected to a docker container.
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Supports persistent sessions that survive WebSocket disconnections.
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Multiple WebSocket connections can attach/detach from the same session.
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"""
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# Circular buffer size (10KB)
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BUFFER_SIZE = 10 * 1024
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# Idle timeout in seconds (30 minutes)
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IDLE_TIMEOUT = 30 * 60
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def __init__(self, session_id: str, instance_id: uuid.UUID, container_id: str, startup_command: str | None = None) -> None:
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# Session number counter per instance_id for auto-naming
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_instance_counters: dict[str, int] = {}
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def __init__(
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self,
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session_id: str,
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instance_id: uuid.UUID,
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container_id: str,
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startup_command: str | None = None,
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name: str | None = None,
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) -> None:
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self.session_id = session_id
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self.instance_id = instance_id
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self.container_id = container_id
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@@ -38,37 +48,52 @@ class TerminalSession:
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self._closed = False
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self._master_fd: int | None = None
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self._slave_fd: int | None = None
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# Circular buffer for output replay
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self._output_buffer: deque[bytes] = deque(maxlen=self.BUFFER_SIZE)
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self._buffer_size = 0
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# WebSocket connections
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self._websockets: set[Any] = set()
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# Activity tracking
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self.last_activity = time.time()
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# Terminal size
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self._cols = 80
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self._rows = 24
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# Session metadata
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self.name = name or self._generate_name(str(instance_id))
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self.status: str = "active"
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@classmethod
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def _generate_name(cls, instance_id: str) -> str:
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"""Generate an auto-incremented session name for the instance."""
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count = cls._instance_counters.get(instance_id, 0) + 1
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cls._instance_counters[instance_id] = count
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return f"Session {count}"
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async def start(self, startup_command: str | None = None) -> None:
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"""Start the docker exec process with a shell using a PTY."""
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# Create a pseudo-terminal on the host
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self._master_fd, self._slave_fd = pty.openpty()
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# Set the terminal size initially
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self._set_terminal_size(self._cols, self._rows)
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logger.debug(f"Starting terminal session {self.session_id} for container {self.container_id} with initial size {self._cols}x{self._rows}")
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logger.debug(
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f"Starting terminal session {self.session_id} for container {self.container_id} with initial size {self._cols}x{self._rows}"
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)
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# Build the shell command
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if startup_command:
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shell_cmd = f'bash -c "{startup_command}" || true; exec bash -il'
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logger.debug(f"Using startup command for session {self.session_id}: {startup_command}")
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logger.debug(
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f"Using startup command for session {self.session_id}: {startup_command}"
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)
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else:
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shell_cmd = "bash -il"
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# Start docker exec with the slave fd as stdin/stdout/stderr
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# Using -it because the slave fd IS a TTY
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self.process = await asyncio.create_subprocess_exec(
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@@ -85,11 +110,11 @@ class TerminalSession:
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stdout=self._slave_fd,
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stderr=self._slave_fd,
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)
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# Close slave fd in parent process
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os.close(self._slave_fd)
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self._slave_fd = None
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self.last_activity = time.time()
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def _set_terminal_size(self, cols: int, rows: int) -> None:
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@@ -99,7 +124,7 @@ class TerminalSession:
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return
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# TIOCSWINSZ = 0x5414 on Linux
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TIOCSWINSZ = 0x5414
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size = struct.pack('HHHH', rows, cols, 0, 0)
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size = struct.pack("HHHH", rows, cols, 0, 0)
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try:
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fcntl.ioctl(self._master_fd, TIOCSWINSZ, size)
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logger.debug(f"Resized PTY to {cols}x{rows} (fd={self._master_fd})")
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@@ -127,7 +152,7 @@ class TerminalSession:
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"""Add data to circular buffer, maintaining size limit."""
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self._output_buffer.append(data)
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self._buffer_size += len(data)
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# Trim if exceeds max size
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while self._buffer_size > self.BUFFER_SIZE and self._output_buffer:
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removed = self._output_buffer.popleft()
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@@ -152,16 +177,16 @@ class TerminalSession:
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if self._closed:
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logger.warning("Cannot resize: session is closed")
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return
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# Only resize if dimensions actually changed
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if cols == self._cols and rows == self._rows:
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return
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self._cols = cols
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self._rows = rows
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logger.debug(f"resize() called for session {self.session_id}: {cols}x{rows}")
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self._set_terminal_size(cols, rows)
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# Docker exec -it creates its own PTY inside the container,
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# so host PTY resize doesn't propagate to the container shell.
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# Send SIGWINCH to the docker exec process on the host.
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@@ -170,14 +195,19 @@ class TerminalSession:
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if self.process and self.process.pid:
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try:
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os.kill(self.process.pid, signal.SIGWINCH)
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logger.debug(f"Sent SIGWINCH to docker exec process {self.process.pid} for session {self.session_id}")
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logger.debug(
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f"Sent SIGWINCH to docker exec process {self.process.pid} for session {self.session_id}"
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)
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except ProcessLookupError:
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logger.warning(f"docker exec process {self.process.pid} not found for session {self.session_id}")
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logger.warning(
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f"docker exec process {self.process.pid} not found for session {self.session_id}"
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)
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except Exception as e:
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logger.warning(f"Failed to send SIGWINCH: {e}")
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async def reset(self) -> None:
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"""Reset the session by killing the process and clearing state."""
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self.status = "resetting"
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await self.close()
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self._closed = False
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self._output_buffer.clear()
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@@ -186,18 +216,20 @@ class TerminalSession:
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self.process = None
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self._master_fd = None
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self._slave_fd = None
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self.status = "active"
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async def close(self) -> None:
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"""Close the session and cleanup."""
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if self._closed:
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return
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self._closed = True
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self.status = "closed"
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if self._master_fd is not None:
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try:
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os.close(self._master_fd)
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except OSError:
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pass
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pass # noqa: S110
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self._master_fd = None
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if self.process is not None:
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@@ -240,7 +272,7 @@ class TerminalSession:
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await ws.send_bytes(data)
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except Exception:
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dead_sockets.add(ws)
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# Clean up dead sockets
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for ws in dead_sockets:
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self._websockets.discard(ws)
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