https://prefect.io logo
Join Slack
Powered by
<@ULVA73B9P> how can I run a flow and see flow log...
# ask-marvin
a
@Marvin how can I run a flow and see flow logs in command line in Prefect 2.x
m
To run a flow and see the logs in the command line with Prefect 2.x, you can follow these general steps: 1. Define your flow: Use the 
@flow
decorator to define your flow in a Python script. Make sure to include logging using 
get_run_logger()
for capturing logs.
Copy code
python
   from prefect import flow, get_run_logger

   @flow
   def my_flow():
       logger = get_run_logger()
       <http://logger.info|logger.info>("This is a log message from my flow.")
2. Run the flow from the command line: You can execute the script directly using Python. Make sure your Prefect environment is configured correctly (e.g., Prefect server or Prefect Cloud is set up).
Copy code
bash
   python my_flow_script.py
3. View logs: The logs will appear in the command line where you ran the script. The logging mechanism in Prefect ensures that logs are captured and can also be viewed in the Prefect UI if configured to a backend. For more detailed guidance, you can refer to the Prefect 2.x documentation on running flows and logging.
a
@Marvin thanks marvin, how can I pass params when calling from command line?
m
To pass parameters to a flow from the command line in Prefect 2.x, you can use the 
prefect deployment run
command with the 
--params
option. This allows you to specify parameters as a JSON string. Here's how you can do it: 1. Define your flow with parameters:
Copy code
python
   from prefect import flow

   @flow
   def my_flow(param1: int, param2: str):
       print(f"Parameter 1: {param1}, Parameter 2: {param2}")
2. Run your flow with parameters: You can pass parameters using the 
--params
flag in your command line execution:
Copy code
bash
   prefect deployment run 'my-flow-deployment' --params '{"param1": 42, "param2": "Hello"}'
This command will execute the flow with the specified parameters. For more details, you can refer to the Prefect 2.x documentation on deployments and parameters.
n
@Marvin locally why not just use sys.argv
m
You're right; if you're running a Prefect flow locally and want to pass parameters via the command line without involving Prefect's deployment features, you can indeed use 
sys.argv
to parse command-line arguments directly in your script. Here's a simple example: 1. Modify your flow to accept parameters from 
sys.argv
:
Copy code
python
   import sys
   from prefect import flow

   @flow
   def my_flow(param1: int, param2: str):
       print(f"Parameter 1: {param1}, Parameter 2: {param2}")

   if __name__ == "__main__":
       param1 = int(sys.argv[1])
       param2 = sys.argv[2]
       my_flow(param1, param2)
2. Run your script with command-line arguments:
Copy code
bash
   python my_flow_script.py 42 "Hello"
This approach leverages Python's standard library to handle command-line arguments directly, which can be more straightforward for local execution without Prefect's orchestration layer.
2 Views
Open in Slack
PreviousNext
Powered by