<@ULVA73B9P> What environment variable/setting do ...
# ask-marvin
d
@Marvin What environment variable/setting do I have to set/look at to know which/where my Prefect server is hosted, and where the flow runs would be ran? For example, if I hosted a Prefect server on AWS ECS through a load balancer. How would I ensure that local runs on my computer submit flows to that ECS instance?
m
thought for 35.7 seconds
For your specific scenario, here's what you need to know: 1. Server Connection Setting: - The primary environment variable is
PREFECT_API_URL
- This should point to your AWS ECS load balancer URL, for example:
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     export PREFECT_API_URL="<https://your-load-balancer-url.amazonaws.com>"
2. Verifying/Setting the Configuration: You can: - Set it temporarily using the export command above - Set it permanently in your Prefect profile using:
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     prefect config set PREFECT_API_URL="<https://your-load-balancer-url.amazonaws.com>"
- View your current settings using:
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     prefect config view
3. Flow Run Location: - The
PREFECT_API_URL
only controls where flows are registered and where their state is tracked - The actual execution location of flow runs depends on your worker and work pool configuration - When you run flows locally with
flow.serve()
or
python flow.py
, they will run on your local machine but report their status to the remote server - For automated deployments, you'll need to set up workers in your execution environment (like ECS) that pull work from your work pools 4. Authentication (if needed): - If your server requires authentication, you'll also need to set
PREFECT_API_KEY
- This can be done similarly:
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     export PREFECT_API_KEY="your-api-key"
     # or
     prefect config set PREFECT_API_KEY="your-api-key"
To verify your configuration is working: 1. Set the
PREFECT_API_URL
as described above 2. Run
prefect config view
to confirm the settings 3. Try running a simple flow - if it can communicate with your server, you'll see the flow run appear in the UI at your ECS-hosted server Remember that this only configures where your client communicates with the Prefect server. The actual execution environment for your flows will depend on your deployment configuration and worker setup.
d
@Marvin What if I want to connect this AWS hosted Prefect server to a Postgres database also hosted on AWS (through RDS)
m
thought for 50.2 seconds
Here's how to configure your Prefect server to use an AWS RDS PostgreSQL instance: 1. Database Connection Configuration: The main setting you need is the database URL. Set it using:
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   export PREFECT_SERVER_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:password@your-rds-endpoint:5432/database_name>"
Or add it to your Prefect profile:
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   prefect config set PREFECT_SERVER_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:password@your-rds-endpoint:5432/database_name>"
2. Connection Pool Settings: For production environments, you should configure the connection pool:
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   # Maximum number of database connections in the pool
   export PREFECT_SERVER_DATABASE_SQLALCHEMY_POOL_SIZE=20
   
   # Connection recycling time in seconds
   export PREFECT_SERVER_DATABASE_SQLALCHEMY_POOL_RECYCLE=1800
   
   # Connection timeout in seconds
   export PREFECT_SERVER_DATABASE_SQLALCHEMY_POOL_TIMEOUT=60
3. PostgreSQL Notification Settings: These control how Prefect handles PostgreSQL NOTIFY/LISTEN connections:
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   # Interval for reconnecting to Postgres for notifications
   export PREFECT_SERVER_SERVICES_TRIGGERS_PG_NOTIFY_RECONNECT_INTERVAL_SECONDS=60
   
   # Heartbeat interval for Postgres notifications
   export PREFECT_SERVER_SERVICES_TRIGGERS_PG_NOTIFY_HEARTBEAT_INTERVAL_SECONDS=30
4. Database Initialization: Before starting the server, you need to initialize the database:
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   prefect server database reset
⚠️ Warning: This command will reset your database. For production, you might want to just run migrations instead:
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   prefect server database upgrade
5. Security Considerations: - Ensure your RDS security group allows incoming connections from your Prefect server - Use AWS Secrets Manager or environment variables to manage database credentials securely - Consider using SSL for database connections by adding
?sslmode=require
to your connection URL 6. Example Complete Configuration: Here's a complete example using an AWS RDS instance:
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   # Database Connection
   export PREFECT_SERVER_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:password@your-rds.xxxxx.region.rds.amazonaws.com:5432/prefect?sslmode=require>"
   
   # Connection Pool Settings
   export PREFECT_SERVER_DATABASE_SQLALCHEMY_POOL_SIZE=20
   export PREFECT_SERVER_DATABASE_SQLALCHEMY_POOL_RECYCLE=1800
   export PREFECT_SERVER_DATABASE_SQLALCHEMY_POOL_TIMEOUT=60
   
   # Notification Settings
   export PREFECT_SERVER_SERVICES_TRIGGERS_PG_NOTIFY_RECONNECT_INTERVAL_SECONDS=60
   export PREFECT_SERVER_SERVICES_TRIGGERS_PG_NOTIFY_HEARTBEAT_INTERVAL_SECONDS=30
7. Verifying the Configuration: After setting up, you can: - Check your configuration:
prefect config view
- Test database connectivity:
prefect server database status
- Start the server:
prefect server start
Remember to: - Back up your database regularly - Monitor connection pool usage and adjust pool settings based on your workload - Keep track of database migrations when upgrading Prefect - Consider using AWS IAM authentication for RDS if appropriate for your security requirements If you encounter any connection issues, verify: 1. The RDS instance is accessible from your Prefect server's network 2. The security group rules allow the connection 3. The database user has appropriate permissions 4. The database exists and is properly initialized with Prefect schemas