From bad3ef7003e1c5f4329840c25a6ed05b7d0b8de1 Mon Sep 17 00:00:00 2001
From: grossmj <grossmj@gns3.net>
Date: Sat, 17 Apr 2021 18:33:20 +0930
Subject: [PATCH] Detect the app is exiting and avoid reconnecting to computes.

---
 gns3server/api/server.py         | 14 +++++++++++++-
 gns3server/controller/compute.py |  5 +++--
 gns3server/core/tasks.py         |  2 +-
 gns3server/server.py             | 11 ++---------
 4 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/gns3server/api/server.py b/gns3server/api/server.py
index de2310eb..da948299 100644
--- a/gns3server/api/server.py
+++ b/gns3server/api/server.py
@@ -25,7 +25,7 @@ from fastapi import FastAPI, Request
 from starlette.exceptions import HTTPException as StarletteHTTPException
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import JSONResponse
-
+from uvicorn.main import Server as UvicornServer
 
 from gns3server.controller.controller_error import (
     ControllerError,
@@ -82,6 +82,18 @@ def get_application() -> FastAPI:
 
 app = get_application()
 
+# Monkey Patch uvicorn signal handler to detect the application is shutting down
+app.state.exiting = False
+unicorn_exit_handler = UvicornServer.handle_exit
+
+
+def handle_exit(*args, **kwargs):
+    app.state.exiting = True
+    unicorn_exit_handler(*args, **kwargs)
+
+
+UvicornServer.handle_exit = handle_exit
+
 
 @app.exception_handler(ControllerError)
 async def controller_error_handler(request: Request, exc: ControllerError):
diff --git a/gns3server/controller/compute.py b/gns3server/controller/compute.py
index 04c73950..4c5969f0 100644
--- a/gns3server/controller/compute.py
+++ b/gns3server/controller/compute.py
@@ -21,7 +21,6 @@ import asyncio
 import async_timeout
 import socket
 import json
-import uuid
 import sys
 import io
 from operator import itemgetter
@@ -295,6 +294,7 @@ class Compute:
         """
         :param topology_dump: Filter to keep only properties require for saving on disk
         """
+
         if topology_dump:
             return {
                 "compute_id": self._id,
@@ -486,7 +486,8 @@ class Compute:
             log.info(f"Connection closed to compute '{self._id}' WebSocket '{ws_url}'")
 
         # Try to reconnect after 1 second if server unavailable only if not during tests (otherwise we create a ressources usage bomb)
-        if self.id != "local" and not hasattr(sys, "_called_from_test") or not sys._called_from_test:
+        from gns3server.api.server import app
+        if not app.state.exiting and not hasattr(sys, "_called_from_test") or not sys._called_from_test:
             log.info(f"Reconnecting to to compute '{self._id}' WebSocket '{ws_url}'")
             asyncio.get_event_loop().call_later(1, lambda: asyncio.ensure_future(self.connect()))
 
diff --git a/gns3server/core/tasks.py b/gns3server/core/tasks.py
index 5080c7d9..f1a95556 100644
--- a/gns3server/core/tasks.py
+++ b/gns3server/core/tasks.py
@@ -82,7 +82,7 @@ def create_startup_handler(app: FastAPI) -> Callable:
 
 def create_shutdown_handler(app: FastAPI) -> Callable:
     """
-    Tasks to be performed when the server is shutdown.
+    Tasks to be performed when the server is exiting.
     """
 
     async def shutdown_handler() -> None:
diff --git a/gns3server/server.py b/gns3server/server.py
index 409d35cb..3c7dedb1 100644
--- a/gns3server/server.py
+++ b/gns3server/server.py
@@ -38,7 +38,6 @@ from gns3server.version import __version__
 from gns3server.config import Config
 from gns3server.crash_report import CrashReport
 from gns3server.api.server import app
-
 from pydantic import ValidationError
 
 import logging
@@ -170,22 +169,16 @@ class Server:
         config.Server.certkey = args.certkey
         config.Server.enable_ssl = args.ssl
 
-    async def reload_server(self):
-        """
-        Reload the server.
-        """
-
-        await Controller.instance().reload()
-
     def _signal_handling(self):
         def signal_handler(signame, *args):
 
             try:
                 if signame == "SIGHUP":
                     log.info(f"Server has got signal {signame}, reloading...")
-                    asyncio.ensure_future(self.reload_server())
+                    asyncio.ensure_future(Controller.instance().reload())
                 else:
                     log.info(f"Server has got signal {signame}, exiting...")
+                    # send SIGTERM to the server PID so uvicorn can shutdown the process
                     os.kill(os.getpid(), signal.SIGTERM)
             except asyncio.CancelledError:
                 pass