Error: spawn python ENOENT when user try to run promptfoo with python:provider

[Oksana]

Hi!
I try to run sample code from examples/python-provider/promptfooconfig.yaml and I get an error

node:events:492
      throw er; // Unhandled 'error' event
      ^

Error: spawn python ENOENT
    at ChildProcess._handle.onexit (node:internal/child_process:286:19)
    at onErrorNT (node:internal/child_process:484:16)
    at process.processTicksAndRejections (node:internal/process/task_queues:82:21)
Emitted 'error' event on PythonShell instance at:
    at ChildProcess.<anonymous> (/Users/ogorbachenko/.npm/_npx/81bbc6515d992ace/node_modules/python-shell/index.js:180:18)
    at ChildProcess.emit (node:events:514:28)
    at ChildProcess._handle.onexit (node:internal/child_process:292:12)
    at onErrorNT (node:internal/child_process:484:16)
    at process.processTicksAndRejections (node:internal/process/task_queues:82:21) {
  errno: -2,
  code: 'ENOENT',
  syscall: 'spawn python',
  path: 'python',
  spawnargs: [
    '/Users/name/.npm/_npx/81bbc6515d992ace/node_modules/promptfoo/dist/src/python/wrapper.py',
    '/Users/name/Projects/dataQA/promptfoo_samples/examples/python-provider/provider.py',
    'call_api',
    '"Write a tweet about bananas"',
    '{"id":"python:provider.py","config":{"someOption":"foobar","basePath":""}}',
    '{"vars":{"topic":"bananas"}}'
  ]
}

Node.js v20.5.1

promptfoo version 0.50.1

Any idea why this is happening?

[Ian Webster]

This means that node isn't able to find the Python executable. By default, this is just python. Ensure that python is installed on your system and that you're in a virtualenv (or whatever is necessary to locate the executable).

If desired, you can manually override the python binary path using the environment variable PROMPTFOO_PYTHON. For example:

PROMPTFOO_PYTHON=venv/bin/python3.9 npx promptfoo@latest eval

[Oksana]

Thanks!!