Textures not exported by python script

Describe the bug I use the following script to export to GLTF:

import bpy
import sys
from pathlib import Path

argv = sys.argv
argv = argv[argv.index("--") + 1 :]  # get all args after "--"

filename = Path(argv[0])

bpy.ops.wm.open_mainfile(filepath=str(filename))
bpy.ops.export_scene.gltf(
    filepath=str(filename.with_suffix(".gltf")),
    export_format="GLTF_EMBEDDED",
    export_yup=True,
)

With the default blender cube with any texture applied, I get the following, and the export file doesn’t contain the texture:

Blender 2.93.5 (hash a791bdabd0b2 built 2021-10-13 00:53:14)
Read prefs: /home//.config/blender/2.93/config/userpref.blend
Read blend: models/untitled.blend
'/usr/bin/2.93/python/lib/python3.9/site-packages/libextern_draco.so' does not exist, draco mesh compression not available
10:31:49 | INFO: Starting glTF 2.0 export
10:31:49 | INFO: Extracting primitive: Cube
10:31:49 | INFO: Primitives created: 1
10:31:49 | WARNING: Image '<bpy_struct, Image("ds5.png") at 0x7f7e23485408>' has no color channels and cannot be exported.
10:31:49 | INFO: Finished glTF 2.0 export in 0.004320383071899414 s

It works fine if I export using the GUI. Am I missing something?

To Reproduce Steps to reproduce the behavior:

1. Create new blender file, add a cube, add a texture to the cube.
2. Run blender --background --python export.py -- <model>.blend
3. Open the gltf file and list the textures

Expected behavior The gui and python script should both generate the same result.

Version

• OS: archlinux
• Blender Version: 2.93.5

[julienduroure]

Here is the ticket: https://developer.blender.org/T95550

[julienduroure]

Not sure what I did last time, but I can reproduce now. Seems to be an Blender API issue, that doesn’t retrieve texture (and even some node) correctly when used in background. I will open some issue in Blender tracker.