Adopt Ubuntu 24.04 image in GitHub Actions test workflow

[Stormheg]

GitHub Actions is transitioning to a new runner image based on Ubuntu 24.04. When this image is used, the testsuite fails because there are issues with the Wand / ImageMagick integration. Expand the details below to see a full copy of the test log from GitHub Actions.

All our previous runs were using the Ubuntu 22.04 runner which had no issues.

 Image: ubuntu-24.04
 Version: 20250105.1.0
 Included Software: https://github.com/actions/runner-images/blob/ubuntu24/20250105.1/images/ubuntu/Ubuntu2404-Readme.md
 Image Release: https://github.com/actions/runner-images/releases/tag/ubuntu24%2F20250105.1

Run coverage run --parallel-mode -m runtests

/opt/hostedtoolcache/Python/3.10.16/x64/lib/python3.10/site-packages/coverage/core.py:70: CoverageWarning: sys.monitoring isn't available, using default core (no-sysmon)
  warn("sys.monitoring isn't available, using default core", slug="no-sysmon")
...............................................................................................................x............x..................................xx........x........................................E...x....x...EE..F.......
======================================================================
ERROR: test_save_as_avif (tests.test_wand.TestWandOperations)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/runner/work/Willow/Willow/tests/test_wand.py", line 310, in test_save_as_avif
    return_value = self.image.save_as_avif(output)
  File "/home/runner/work/Willow/Willow/willow/plugins/wand.py", line 274, in save_as_avif
    converted.save(file=f)
  File "/opt/hostedtoolcache/Python/3.10.16/x64/lib/python3.10/site-packages/wand/image.py", line 10202, in save
    file.write(self.make_blob())
TypeError: a bytes-like object is required, not 'NoneType'

======================================================================
ERROR: test_save_avif_lossless (tests.test_wand.TestWandOperations)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/runner/work/Willow/Willow/tests/test_wand.py", line 327, in test_save_avif_lossless
    lossless_file = self.image.save_as_avif(io.BytesIO(), lossless=True)
  File "/home/runner/work/Willow/Willow/willow/plugins/wand.py", line 274, in save_as_avif
    converted.save(file=f)
  File "/opt/hostedtoolcache/Python/3.10.16/x64/lib/python3.10/site-packages/wand/image.py", line 10202, in save
    file.write(self.make_blob())
TypeError: a bytes-like object is required, not 'NoneType'

======================================================================
ERROR: test_save_avif_quality (tests.test_wand.TestWandOperations)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/runner/work/Willow/Willow/tests/test_wand.py", line 319, in test_save_avif_quality
    high_quality = self.image.save_as_avif(io.BytesIO(), quality=90)
  File "/home/runner/work/Willow/Willow/willow/plugins/wand.py", line 274, in save_as_avif
    converted.save(file=f)
  File "/opt/hostedtoolcache/Python/3.10.16/x64/lib/python3.10/site-packages/wand/image.py", line 10202, in save
    file.write(self.make_blob())
TypeError: a bytes-like object is required, not 'NoneType'

======================================================================
FAIL: test_save_webp_quality (tests.test_wand.TestWandOperations)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/runner/work/Willow/Willow/tests/test_wand.py", line 380, in test_save_webp_quality
    self.assertTrue(low_quality.f.tell() < high_quality.f.tell())
AssertionError: False is not true

We must figure out what difference is causing the issue so we can adopt the Ubuntu 24.04 image. I already know the 24.04 image does not have ImageMagick installed by default, but apt install imagemagick results in the testsuite failure above.

Fortunately, the folks at GitHub have quite good documentation about what's installed in their images. Might be helpful.

• Ubuntu 24.04: https://github.com/actions/runner-images/blob/ubuntu24/20250126.1/images/ubuntu/Ubuntu2404-Readme.md
• Ubuntu 22.04: https://github.com/actions/runner-images/blob/ubuntu22/20250126.1/images/ubuntu/Ubuntu2204-Readme.md

See also #160

[joelwilliam2005]

I tried to install imagemagick on ubuntu 24.04 using docker.
Commands:

apt update
apt install libpng-dev libjpeg-dev libtiff-dev
apt install imagemagick

Here,

which magick , magick --version

return none.
There is no executable for it.

However convert can be accessed, which is also a cli tool for imagemagick which was replaced by magick command.

convert --version returns:

Version: ImageMagick 6.9.12-98 Q16 x86_64 18038 https://legacy.imagemagick.org
Copyright: (C) 1999 ImageMagick Studio LLC
License: https://imagemagick.org/script/license.php
Features: Cipher DPC Modules OpenMP(4.5) 
Delegates (built-in): bzlib djvu fftw fontconfig freetype heic jbig jng jp2 jpeg lcms lqr ltdl lzma openexr pangocairo png raw tiff webp wmf x xml zlib

A fix I had thought would've been to create a symlink.

sudo ln -s /usr/bin/convert /usr/bin/magick

This makes magick command usable but still gave no signs of solving the issue. I think the issue lies in Willow accessing imagemagick using magick command.

Adding some references that I used:

• https://linuxcapable.com/how-to-install-imagemagick-on-ubuntu-linux/
• https://medium.com/@formasitf/resolving-compatibility-issues-with-imagemagick-on-ubuntu-24-04-81c063a5ed83
• https://askubuntu.com/questions/1315603/where-is-the-magick-command-of-imagemagick
• convert Command Not Found on Ubuntu 24.04 alshedivat/al-folio#2902

[zerolab]

We're accessing imagemagick via Wand which provides the ctype bindings for Python.

[joelwilliam2005]

I was able to reproduce the issue on ubuntu 24.04 docker container, can't seem to find the root cause.

[Stormheg]

I dug into this today and now I'm (temporarily) out of motivation.

There is something specifically wrong with the combination of AVIF + ImageMagick + Ubuntu 24.04. Possibly with WebP as well since test_save_webp_quality also fails.

I focused on the NoneType error raised by the save_as_avif tests. The code that silently returns None is the make_blob function in Wand:

https://github.com/emcconville/wand/blob/9d4491f5c6540f67960958857006fd713b865018/wand/image.py#L10177-L10185

library.MagickResetIterator(self.wand)
length = ctypes.c_size_t()
blob_p = None
if library.MagickGetNumberImages(self.wand) > 1:
    blob_p = library.MagickGetImagesBlob(self.wand,
                                            ctypes.byref(length))
else:
    blob_p = library.MagickGetImageBlob(self.wand,
                                        ctypes.byref(length))
if blob_p and length.value:
    blob = ctypes.string_at(blob_p, length.value)
    blob_p = library.MagickRelinquishMemory(blob_p)
    return blob
else:  # pragma: no cover
    self.raise_exception()

library.MagickGetImageBlob is supposed to do something and store it in memory. It returns a pointer to memory in blob_p and the size of the memory region allocated in length. Somehow length and pointer both remain zero, which means we never trigger the if statement that reads and returns the memory using ctypes.string_at.

This situation is supposed to be caught by the final else which goes looking for an exception but there does not appear to be one. Hence we fall through to returning None in make_blob, the default return value in Python when a function has no final return.

Still not sure what happens inside the ImageMagick 'black box'...