There are a few potential issues with running Prefect workers as a Windows service via NSSM that I can help you address: 1. Environment Variables: When running as a service, the environment might not have the same variables as your interactive session. The service needs access to your Prefect Cloud API key. Add this to your batch file:

batch
REM Set Prefect Cloud API key
set PREFECT_API_KEY=your-api-key-here

2. Working Directory: NSSM should set the working directory explicitly. In NSSM configuration: - Set "Application Path" to

D:\PrefectServer\SharedLibs\venvbiteam\Scripts\python.exe

- Set "Startup Directory" to

D:\PrefectServer\SharedLibs

- Set "Arguments" to

-m prefect worker start --pool "Worker Pool" --work-queue "default"

3. Modified Batch File: Here's an improved version of your batch file:

batch
@echo off
REM -----------------------------------------------
REM Prefect Cloud worker startup script via NSSM
REM -----------------------------------------------

REM Set working directory to shared D drive location
cd /d "D:\PrefectServer\SharedLibs"

REM Set Prefect Cloud API key (replace with your actual key)
set PREFECT_API_KEY=your-api-key-here

REM Activate virtual environment
call "D:\PrefectServer\SharedLibs\venvbiteam\Scripts\activate.bat"

REM OPTIONAL: Ensure log directory exists
if not exist "D:\PrefectServer\Logs" mkdir "D:\PrefectServer\Logs"

REM Start Prefect Cloud worker using named pool and queue
python -m prefect worker start --pool "Worker Pool" --work-queue "default" > D:\PrefectServer\Logs\prefect_worker.log 2>&1

4. NSSM Configuration Steps:

batch
   REM Install the service (run as administrator)
   nssm install PrefectWorker "D:\PrefectServer\SharedLibs\venvbiteam\Scripts\python.exe"
   nssm set PrefectWorker AppDirectory "D:\PrefectServer\SharedLibs"
   nssm set PrefectWorker AppParameters "-m prefect worker start --pool \"Worker Pool\" --work-queue \"default\""
   nssm set PrefectWorker AppEnvironment "PREFECT_API_KEY=your-api-key-here"

5. Troubleshooting Steps: - Check the Windows Event Viewer for service-related errors - Look at

D:\PrefectServer\Logs\prefect_worker.log

- Make sure the service account has proper permissions to: - Access the virtual environment - Write to the logs directory - Access the network for Prefect Cloud communication 6. Additional NSSM Settings to Consider: - Set appropriate service recovery options:

batch
     nssm set PrefectWorker AppRestartDelay 10000
     nssm set PrefectWorker AppStopMethodConsole 15000

- Configure stdout/stderr redirection:

batch
     nssm set PrefectWorker AppStdout "D:\PrefectServer\Logs\prefect_worker.log"
     nssm set PrefectWorker AppStderr "D:\PrefectServer\Logs\prefect_worker_error.log"

Since you mentioned it works when running directly in the terminal but not as a service, the most likely issues are: 1. Missing environment variables (especially PREFECT_API_KEY) 2. Service account permissions 3. Python path resolution in the service context Try implementing these changes and check the logs. If you're still having issues, please share: 1. Any error messages from the logs 2. The output of

nssm get PrefectWorker AppEnvironment

3. Whether the service starts but fails, or fails to start at all