In the previous lesson, we covered the basics of running your Runpod serverless functions locally. Now, let’s explore some advanced options that give you more control over your local testing environment. The Runpod Python SDK provides several command-line arguments that allow you to customize your local testing setup. Let’s go through each of these options:

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Controlling Log Levels

--rp_log_level ERROR | WARN | INFO | DEBUG
This argument allows you to set the verbosity of the console output. Options are:
  • ERROR: Only show error messages
  • WARN: Show warnings and errors
  • INFO: Show general information, warnings, and errors
  • DEBUG: Show all messages, including detailed debug information
Example: 
python hello_world.py --rp_server_api --rp_log_level DEBUG
The --rp_log_level flag enables the Runpod debugger, which can help you troubleshoot issues in your code. Example: 
python hello_world.py --rp_server_api --rp_debugger

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Customizing the API Server

The following arguments allow you to configure the FastAPI server that simulates the Runpod serverless environment: 
--rp_serve_api
--rp_api_port <port_number>
--rp_api_concurrency <number_of_workers>
--rp_api_host <hostname>
  • --rp_serve_api: Starts the API server
  • --rp_api_port: Sets the port number (default is 8000)
  • --rp_api_concurrency: Sets the number of concurrent workers (default is 1)
  • --rp_api_host: Sets the hostname (default is “localhost”)
Example: 
python hello_world.py --rp_serve_api --rp_api_port 8080 --rp_api_concurrency 4 --rp_api_host 0.0.0.0
This command starts the API server on port 8080 with 4 concurrent workers and makes it accessible from other devices on the network.

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Providing test input

As we saw in the previous lesson, you can provide test input either through a JSON file or directly via the command line: 
--test_input '<JSON_string>'
Example: 
python hello_world.py --rp_server_api --test_input '{"input": {"name": "Runpod"}}'
You can combine these arguments to create a highly customized local testing environment. Here’s an example that uses multiple options: 
python hello_world.py --rp_server_api --rp_log_level DEBUG --rp_debugger --rp_api_port 8080 --rp_api_concurrency 2 --test_input '{"input": {"name": "Advanced Tester"}}'
This command:
  1. Starts the local server
  2. Sets the log level to DEBUG for maximum information
  3. Enables the debugger
  4. Uses port 8080 for the API server
  5. Sets up 2 concurrent workers
  6. Provides a test input directly in the command

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Conclusion

These advanced options for local testing with the Runpod Python SDK give you fine-grained control over your development environment. By mastering these tools, you can ensure your serverless functions are robust and ready for deployment to the Runpod cloud. In the next lesson, we’ll explore how to structure more complex handlers to tackle advanced use cases in your serverless applications.