https://prefect.io logo
Join Slack
Powered by
<@ULVA73B9P> Why would deployments with a cron sch...
# marvin-ai
s
@Marvin Why would deployments with a cron schedule not configure runs to be scheduled?
m
✅ thought for 53.1 seconds
Based on the research and GitHub issues, there are several common reasons why deployments with cron schedules might not configure runs as expected: 1. Scheduler Constraints - Prefect has built-in limitations that prevent scheduling: - No more than 100 runs at a time - No scheduling beyond 100 days into the future - These are safety measures to prevent overwhelming the system 2. Time Zone Configuration - Incorrect time zone settings in the deployment configuration can cause schedules to behave unexpectedly - Always explicitly specify the timezone in your schedule configuration:
Copy code
yaml
   schedules:
     - cron: "0 9 * * *"
       timezone: "UTC"  # or your local timezone like "America/New_York"
3. Schedule Updates - When you modify a schedule, Prefect automatically removes any previously scheduled (but not started) runs - New runs are created based on the updated schedule - This can sometimes make it appear as if runs aren't being scheduled if you're looking for old scheduled runs 4. Invalid Cron Expressions - Incorrect cron syntax will prevent runs from being scheduled - You can validate your cron expressions using online tools before implementing them 5. Deployment Active Status - Make sure the deployment itself is active - Check that the schedule within the deployment is marked as 
active: true
To troubleshoot scheduling issues: 1. Check the Prefect UI for any error messages or warnings 2. Verify your cron expression is valid 3. Confirm the timezone settings match your expectations 4. Ensure the deployment is active 5. Look at the deployment's schedule configuration to confirm it's properly set If you're still experiencing issues, it would be helpful to: - Share your deployment configuration - Check the Prefect server logs for any error messages - Verify if any runs are being created at all or if they're being created for the wrong times Would you like me to look into any specific aspect of these potential causes in more detail?
s
@Marvin Where can I check the Prefect server logs for any error messages?
m
✅ thought for 33.1 seconds
Here's how you can access Prefect server logs, depending on your deployment type: 1. Self-hosted Prefect Server:
Copy code
bash
   prefect server start
- Logs will appear directly in your terminal - The server UI will be available at http://127.0.0.1:4200 by default - You can see detailed logs about scheduling, deployments, and other server activities - To run the server in the background, you can use 
nohup
on Linux/Mac or run it as a service 2. Prefect Cloud: - Navigate to Account Settings in the Prefect Cloud UI - Look for the 'Audit Log' section (available on Pro and Enterprise plans) - These logs include: - User access to workspaces - Login activities - API key management - Deployment and flow run activities 3. Additional Logging Options: - For more detailed debugging, you can set the log level using environment variables:
Copy code
bash
     export PREFECT_LOGGING_LEVEL="DEBUG"
- This will provide more verbose output about server operations 4. Worker Logs: - Don't forget that workers also generate their own logs - These can be accessed where the worker is running - Use 
prefect worker start
with the 
-d
flag to see detailed logs:
Copy code
bash
     prefect worker start -p "your-pool" -d
If you're troubleshooting specific scheduling issues, the server logs should show entries about: - Schedule evaluations - Creation of new scheduled runs - Any errors preventing schedules from being processed Are you using Prefect Cloud or a self-hosted server? This would help me provide more specific guidance for your setup.
s
@Marvin I am using a self-hosted Linux server. In fact, after a while it pauses deployments and cannot connect to the server: 144415.972 | INFO | prefect.runner - Pausing all deployments... Failed the last 3 attempts. Please check your environment and configuration. Examples of recent errors: Traceback (most recent call last): File "/opt/pawthon/orchestrator/env/lib64/python3.12/site-packages/httpx/_transports/default.py", line 101, in map_httpcore_exceptions yield File "/opt/pawthon/orchestrator/env/lib64/python3.12/site-packages/httpx/_transports/default.py", line 394, in handle_async_request resp = await self._pool.handle_async_request(req) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/opt/pawthon/orchestrator/env/lib64/python3.12/site-packages/httpcore/_async/connection_pool.py", line 256, in handle_async_request raise exc from None File "/opt/pawthon/orchestrator/env/lib64/python3.12/site-packages/httpcore/_async/connection_pool.py", line 236, in handle_async_request response = await connection.handle_async_request( ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/opt/pawthon/orchestrator/env/lib64/python3.12/site-packages/httpcore/_async/connection.py", line 101, in handle_async_request raise exc File "/opt/pawthon/orchestrator/env/lib64/python3.12/site-packages/httpcore/_async/connection.py", line 78, in handle_async_request stream = await self._connect(request) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/opt/pawthon/orchestrator/env/lib64/python3.12/site-packages/httpcore/_async/connection.py", line 124, in _connect stream = await self._network_backend.connect_tcp(**kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/opt/pawthon/orchestrator/env/lib64/python3.12/site-packages/httpcore/_backends/auto.py", line 31, in connect_tcp return await self._backend.connect_tcp( ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/opt/pawthon/orchestrator/env/lib64/python3.12/site-packages/httpcore/_backends/anyio.py", line 113, in connect_tcp with map_exceptions(exc_map): ^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/lib64/python3.12/contextlib.py", line 158, in exit self.gen.throw(value) File "/opt/pawthon/orchestrator/env/lib64/python3.12/site-packages/httpcore/_exceptions.py", line 14, in map_exceptions raise to_exc(exc) from exc httpcore.ConnectError: All connection attempts failed
m
✅ thought for 57.3 seconds
Based on the error message and research, here's what's happening and how to resolve it: 1. Immediate Issue: - The error indicates that your Prefect client (worker/deployment) cannot connect to the Prefect server - After multiple failed attempts, the system is automatically pausing deployments as a safety measure 2. Common Causes: - Network connectivity issues between client and server - Firewall rules blocking connections - Server process has stopped or crashed - Memory pressure causing server instability 3. Troubleshooting Steps: a. Check Server Status:
Copy code
bash
   # Check if server is running
   ps aux | grep prefect
   
   # Check server logs
   journalctl -u prefect-server.service    # if running as a systemd service
   # or check the logs in your server's log directory
b. Verify Network Configuration:
Copy code
bash
   # Check if server port is listening (default 4200)
   netstat -tulpn | grep prefect
   
   # Test connection to server
   curl <http://localhost:4200/api/health>
c. Check Resource Usage:
Copy code
bash
   # Monitor system resources
   top
   free -m
   df -h
4. Resolution Steps: a. Restart Server:
Copy code
bash
   # If running as a service
   sudo systemctl restart prefect-server
   
   # If running directly
   prefect server stop
   prefect server start
b. Configure Server as a Service: Create a systemd service file `/etc/systemd/system/prefect-server.service`:
Copy code
ini
   [Unit]
   Description=Prefect Server
   After=network.target
   
   [Service]
   Type=simple
   User=your_user
   Environment=PREFECT_SERVER_API_HOST=0.0.0.0
   Environment=PREFECT_SERVER_API_PORT=4200
   ExecStart=/path/to/prefect server start
   Restart=always
   RestartSec=1
   
   [Install]
   WantedBy=multi-user.target
Then enable and start it:
Copy code
bash
   sudo systemctl enable prefect-server
   sudo systemctl start prefect-server
5. Preventive Measures: - Set up monitoring for the Prefect server process - Configure proper logging - Implement automatic restart policies - Set up resource limits to prevent memory exhaustion Would you like me to: 1. Provide more specific troubleshooting steps based on your server setup? 2. Help you set up a proper systemd service for more reliable operation? 3. Guide you through setting up monitoring for the server? Also, it would be helpful to know: - How is your server currently being run (directly, as a service, etc.)? - What are your system's resources (RAM, CPU)? - Are you seeing any specific patterns when these failures occur?
j
Hey @Shuler Cotton did you solve this? I'm having the same issue
Open in Slack
PreviousNext
Powered by