feat: add allocated server readiness control

2026-09-13 08:42:05 +00:00 · 2026-09-01 09:12:10 +01:00
parent 5b80c97337
commit 6caf719158
8 changed files with 218 additions and 4 deletions
@@ -0,0 +1,106 @@
+class_name ServerControl
+extends Node
+
+# Small loopback HTTP control surface for allocated servers. The Go supervisor
+# uses GET /ready as the explicit process-ready probe and POST /drain during a
+# controlled termination. Direct/community servers do not start this node.
+
+signal drain_requested
+
+var _listener := TCPServer.new()
+var _peers: Array = []
+var _ready_for_connections := false
+var _draining := false
+var _drain_token := ""
+
+
+func start(port: int, drain_token: String = "") -> Error:
+	if port < 1 or port > 65535:
+		return ERR_INVALID_PARAMETER
+	_drain_token = drain_token
+	return _listener.listen(port, "127.0.0.1")
+
+
+func stop() -> void:
+	_listener.stop()
+	for peer in _peers:
+		if is_instance_valid(peer):
+			peer.disconnect_from_host()
+	_peers.clear()
+
+
+func set_process_ready(value: bool) -> void:
+	_ready_for_connections = value and not _draining
+
+
+func is_draining() -> bool:
+	return _draining
+
+
+func _exit_tree() -> void:
+	stop()
+
+
+func _process(_delta: float) -> void:
+	while _listener.is_connection_available():
+		_peers.append(_listener.take_connection())
+	for i in range(_peers.size() - 1, -1, -1):
+		var peer: StreamPeerTCP = _peers[i]
+		if peer.get_status() != StreamPeerTCP.STATUS_CONNECTED:
+			_peers.remove_at(i)
+			continue
+		var available := peer.get_available_bytes()
+		if available <= 0:
+			continue
+		var request := peer.get_utf8_string(available)
+		if "\r\n\r\n" not in request:
+			continue
+		_respond(peer, request)
+		_peers.remove_at(i)
+
+
+func _respond(peer: StreamPeerTCP, request: String) -> void:
+	var lines := request.split("\r\n")
+	var first := lines[0].split(" ") if not lines.is_empty() else PackedStringArray()
+	var method := String(first[0]) if first.size() > 0 else ""
+	var path := String(first[1]) if first.size() > 1 else ""
+	var status := 404
+	var reason := "Not Found"
+	var body := ""
+	if method == "GET" and path == "/ready":
+		status = 200 if _ready_for_connections else 503
+		reason = "OK" if status == 200 else "Service Unavailable"
+	elif method == "GET" and path == "/health":
+		status = 200
+		reason = "OK"
+	elif method == "POST" and path == "/drain":
+		var supplied := ""
+		for line in lines:
+			if line.begins_with("Authorization: Bearer "):
+				supplied = line.substr("Authorization: Bearer ".length())
+		if _drain_token.is_empty() or not _constant_time_equal(supplied, _drain_token):
+			status = 401
+			reason = "Unauthorized"
+		else:
+			_draining = true
+			_ready_for_connections = false
+			drain_requested.emit()
+			status = 202
+			reason = "Accepted"
+	else:
+		status = 405 if method in ["GET", "POST"] else 400
+		reason = "Method Not Allowed" if status == 405 else "Bad Request"
+	body = "{\"status\":\"%s\"}" % ("ready" if status == 200 else "not_ready")
+	var response := "HTTP/1.1 %d %s\r\nContent-Type: application/json\r\nContent-Length: %d\r\nConnection: close\r\n\r\n%s" % [status, reason, body.to_utf8_buffer().size(), body]
+	peer.put_data(response.to_utf8_buffer())
+	peer.disconnect_from_host()
+
+
+func _constant_time_equal(a: String, b: String) -> bool:
+	var left := a.to_utf8_buffer()
+	var right := b.to_utf8_buffer()
+	var difference := left.size() ^ right.size()
+	var length := mini(left.size(), right.size())
+	for i in length:
+		difference |= left[i] ^ right[i]
+	return difference == 0