Both. Like so: https://github.com/pantsbuild/pants/blob/725fd415c29440a6333c0f131f67e0b531fa0497/src/python/pants/backend/python/lint/pylint/rules.py#L131-L139 If you add an input_digest to that example that includes your script file digest and change requirements to those you need, out plops a Pex you can then use in a Process.