enable optix GPU rendering in blender python

gpu-render.py

import bpy, sys, os

# enable GPU rendering if possible
# use whatever device type is available, in oder of device_type_preferences left-to-right
def set_device_type(device_type_preferences=['OPTIX', 'CUDA', 'CPU']):
    prefs = bpy.context.preferences
    cycles_prefs = prefs.addons['cycles'].preferences

    enabled_devices = []
    for device_type_preference in device_type_preferences:
        if device_type_preference != 'CPU':
            bpy.context.scene.cycles.device = 'GPU'
        else:
            bpy.context.scene.cycles.device = 'CPU'

        cycles_prefs.compute_device_type = device_type_preference
        cycles_prefs.refresh_devices()
        preferred_devices = [device for device in cycles_prefs.devices if device.type == device_type_preference]

        if len(preferred_devices) == 0:
            continue

        for device in preferred_devices:
            device.use = True
            enabled_devices.append(device)
        break

    for enabled_device in enabled_devices:
        print('enabled_device:', enabled_device.name, enabled_device.type)

    bpy.context.scene.cycles.device = 'GPU'

def render_blend_to_png(blend_file, output_png, samples=1000):
    # Open the blend file
    bpy.ops.wm.open_mainfile(filepath=blend_file)

    # Set Cycles as the rendering engine
    bpy.context.scene.render.engine = 'CYCLES'
    set_device_type()

    # Set the number of samples
    bpy.context.scene.cycles.samples = samples

    # Set output file format and path
    bpy.context.scene.render.image_settings.file_format = 'PNG'
    bpy.context.scene.render.filepath = output_png

    # Render the animation
    bpy.ops.render.render(write_still=True)

if __name__ == "__main__":
    # Check if the correct number of command line arguments is provided

    if '--' not in sys.argv:
        print("Usage: blender -b -P gpu-render.py -- <blend_file> <output_png> <samples>")

    sys.argv = sys.argv[sys.argv.index("--") + 1:]
    if len(sys.argv) != 3:
        print("Usage: blender -b -P gpu-render.py -- <blend_file> <output_png> <samples>")
        sys.exit(1)

    # Extract command line arguments
    blend_file = os.path.abspath(sys.argv[0])
    output_png = os.path.abspath(sys.argv[1])
    samples = int(sys.argv[2])

    print('blend_file', blend_file)
    print('output_png', output_png)
    print('samples', samples)

    # Call the rendering function
    render_blend_to_png(blend_file, output_png, samples)

this works as of blender 4.0