Craft Cloud image transformer appears to fail to transform AVIF images

[jamesmacwhite]

We encountered an interesting situation where it appears that AVIF format images were uploaded to the Craft Cloud CDN asset storage bucket and used as the source image for display on the front-end.

It appears the Craft Cloud image transformer doesn't appear to tranform AVIF images at all when calling any transformer properties, and the original asset is served instead, even though the transformer URL query parameters are present in the URL. There is no error but obviously not transforming the image could lead to serving larger images than intended.

AVIF is an interesting format as the source to be fair, it looks like it has come from a bit of unique situation of someone copying a transformed image from another site which had optimised the image delivery and hence AVIF is the format.

At the moment, because of the Craft Cloud AVIF issue, we have blocked subsequent AVIF images from being uploaded with this event:

Event::on(
    Asset::class,
    Asset::EVENT_BEFORE_VALIDATE,
    static function (YiiModelEvent $event) {
        /** @var Asset $asset */
        $asset = $event->sender;

        if (!$asset->propagating) {
            $extension = pathinfo(($asset->newFilename ?? $asset->filename), PATHINFO_EXTENSION);

            if (strtolower($extension) === 'avif') {
                $asset->addError('title', Craft::t('example-module', 'The AVIF image format is not supported as a source image for assets, due to a bug with image transforms. Please use a different image format.'));
            }
        }
    }
);

I was able to query all AVIF image assets as well as add some custom code to find out their usage on other elements and basically do a conversion with imagemagik e.g. convert example.avif example.jpg and replace the asset.

However the transformer silently not transforming AVIF images seems like a bug, so posting here for reference!