feat: add allocated server readiness control

Game/tests/server_control_smoke.gd

@@ -0,0 +1,51 @@
+extends SceneTree
+
+const ServerControlScript = preload("res://scripts/server_control.gd")
+const PORT := 18080
+
+
+func _init() -> void:
+	var control = ServerControlScript.new()
+	root.add_child(control)
+	if control.start(PORT, "drain-secret") != OK:
+		printerr("server control failed to bind")
+		quit(1)
+		return
+	control.set_process_ready(true)
+	await process_frame
+	var ready_response := await _request("GET", "/ready", [])
+	if ready_response != 200:
+		printerr("ready response was %d" % ready_response)
+		quit(1)
+		return
+	var unauthorized := await _request("POST", "/drain", ["Authorization: Bearer wrong"])
+	if unauthorized != 401:
+		printerr("unauthorized drain response was %d" % unauthorized)
+		quit(1)
+		return
+	var drained := await _request("POST", "/drain", ["Authorization: Bearer drain-secret"])
+	if drained != 202 or not control.is_draining():
+		printerr("authorized drain response/state was %d/%s" % [drained, control.is_draining()])
+		quit(1)
+		return
+	var not_ready := await _request("GET", "/ready", [])
+	if not_ready != 503:
+		printerr("draining ready response was %d" % not_ready)
+		quit(1)
+		return
+	control.stop()
+	print("server control smoke passed")
+	quit(0)
+
+
+func _request(method: String, path: String, headers: PackedStringArray) -> int:
+	var request := HTTPRequest.new()
+	root.add_child(request)
+	var http_method := HTTPClient.METHOD_GET if method == "GET" else HTTPClient.METHOD_POST
+	var err := request.request("http://127.0.0.1:%d%s" % [PORT, path], headers, http_method)
+	if err != OK:
+		request.queue_free()
+		return -1
+	var result = await request.request_completed
+	request.queue_free()
+	return int(result[1])