[Python] Run FastAPI in a Windows Service

i have a big problem. I try to run FastAPI as a Windows Service after i converted the scripts in .exe with pyinstaller.

This is my Code in apy.py:

from fastapi import FastAPI, UploadFile, File, HTTPException, Request, Depends
from fastapi.responses import JSONResponse
from pydantic import BaseModel, Field
import pandas as pd
import io
import numpy as np
import logging
from logging.handlers import RotatingFileHandler
import sys
import os
import joblib
from typing import Optional
import json
from fastapi.security import APIKeyHeader
import string
import datetime
import uvicorn



############################################################################
################################# Start ####################################
############################################################################


TicketClassifierPath = os.getenv("TicketClassifierPath")
log_dir = os.path.join(TicketClassifierPath, "logs")
if not os.path.exists(log_dir):
os.makedirs(log_dir)

# Logging einrichten
log_file = os.path.join(log_dir, "api.log")
# RotatingFileHandler konfigurieren
handler = RotatingFileHandler(
log_file,
maxBytes=5 * 1024 * 1024, # 5 MB
backupCount=3 # Anzahl der alten Logfiles, die behalten werden (server.log.1, server.log.2, ...)
)

# Logging-Format
formatter = logging.Formatter("%(asctime)s - %(levelname)s - %(message)s")
handler.setFormatter(formatter)

# Root-Logger konfigurieren
logger = logging.getLogger()
logger.setLevel(logging.INFO)
logger.addHandler(handler)

# FastAPI-App starten
app = FastAPI()

@app.get("/tst")
def apikey():
return {"Hello World"}

def start_api():
logging.info("Start uvicorn")
uvicorn.run(app, host="0.0.0.0", port=8000, log_config=None, reload=False)

if __name__ == '__main__':
start_api()
# Starte den API-Server mit: uvicorn api:app --reload
# Im LAN auf allen Adressen erreichbar mit: uvicorn api:app --host 0.0.0.0 --port 8000 --reload


This is my code in service.py:

import os
import logging
from logging.handlers import RotatingFileHandler
import sys
import win32serviceutil
import win32service
import win32event
import subprocess
import servicemanager
import socket
from pydantic import BaseModel
import json
import time
import api as api_server
import threading

# Unterverzeichnis für Logs erstellen
TicketClassifierPath = os.getenv("TicketClassifierPath")
log_dir = os.path.join(TicketClassifierPath, "logs")
if not os.path.exists(log_dir):
os.makedirs(log_dir)

# Logging einrichten
log_file = os.path.join(log_dir, "service.log")

# RotatingFileHandler konfigurieren
handler = RotatingFileHandler(
log_file,
maxBytes=5 * 1024 * 1024, # 5 MB
backupCount=3 # Anzahl der alten Logfiles, die behalten werden (server.log.1, server.log.2, ...)
)

# Logging-Format
formatter = logging.Formatter("%(asctime)s - %(levelname)s - %(message)s")
handler.setFormatter(formatter)

# Root-Logger konfigurieren
logger = logging.getLogger()
logger.setLevel(logging.INFO)
logger.addHandler(handler)

class AppServerSvc (win32serviceutil.ServiceFramework):
_svc_name_ = "TicketClassifierService"
_svc_display_name_ = "Ticket Classifier API Service"
_svc_description_ = "Dienst für die API des Ticket Classifiers"


def __init__(self,args):
win32serviceutil.ServiceFramework.__init__(self,args)
self.hWaitStop = win32event.CreateEvent(None,0,0,None)
socket.setdefaulttimeout(60)

def SvcStop(self):
self.ReportServiceStatus(win32service.SERVICE_STOP_PENDING)
win32event.SetEvent(self.hWaitStop)

logging.info("Stop requested by service manager.")

if self.process and self.process.poll() is None:
logging.info("Terminating subprocess...")
self.process.terminate()
try:
self.process.wait(timeout=10)
logging.info("Subprocess terminated gracefully.")
except subprocess.TimeoutExpired:
logging.warning("Subprocess did not terminate in time. Killing it.")
self.process.kill()
logging.info("Subprocess killed.")

def SvcDoRun(self):
servicemanager.LogMsg(
servicemanager.EVENTLOG_INFORMATION_TYPE,
servicemanager.PYS_SERVICE_STARTED,
(self._svc_name_,''))
self.main()

def main(self): #Befindet sich hier im Python Pfad

logging.info("Start Service...")

python_path = os.getenv("python", "C:\\Program Files\\Python313\\python.exe")
cmd = [python_path, "service.py", "run"]
TicketClassifierPath = "C:\\Users\\orca\\Desktop\\TicketKIFull\\Ticket KI Small"

######################### For Run as a Exe #########################
#cmd = ["TicketClassifier.exe", "run"]
####################################################################
try:
logging.info(f"Starte Uvicorn-Prozess: {' '.join(cmd)}")
self.process = subprocess.Popen(cmd, cwd=TicketClassifierPath)
logging.info("Subprozess gestartet.")
except Exception as e:
logging.critical(f"Fehler beim Start des Subprozesses: {e}")
return

rc = None
while rc != win32event.WAIT_OBJECT_0:
rc = win32event.WaitForSingleObject(self.hWaitStop, 10 * 1000)
logging.info("Service is alive...")

logging.info("Service wird gestoppt...")
if self.process and self.process.poll() is None:
logging.info("Terminiere Uvicorn-Prozess...")
self.process.terminate()
try:
self.process.wait(timeout=10)
logging.info("Prozess erfolgreich gestoppt.")
except subprocess.TimeoutExpired:
logging.warning("Prozess reagiert nicht, erzwinge Kill.")
self.process.kill()
logging.info("Prozess wurde gekillt.")


if __name__ == '__main__':
if len(sys.argv) > 1 and sys.argv[1] == "run":
api_server.start_api()
else:
win32serviceutil.HandleCommandLine(AppServerSvc)


I tested the following:

• Run api.py manualy "python api.py" -> Works!
• Run service.py manualy "python service.py run" -> Works!
• Create Service with service.py and run that service -> Works! "python service.py install" "python service.py start"
• Create Exe with pyinstaller and Run that -> Works! uncomment in script: "cmd = ["TicketClassifier.exe", "run"]" Create exe with pyinstaller: "pyinstaller --onfile --console --name TicketClassifier --hidden-import=win32timezone service.py" Run the exe File: "TicketClassifier.exe run"
• Create Service with TicketClassifier.exe and run that service -> Doesn´t work!... "TicketClassifier.exe install" "TicketClassifier.exe start" Error 1053 at Start. But why it works before i converted it with pyinstaller?

Anyone have a idea?

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