We’ve updated our image so we’re compiling imagemagick separately and only including the final imagemagick binary, so we are no longer including compile-time libs for imagemagick in the image in an effort to reduce the size of our base images.
You could simply add an install script to install imagemagick libs, but I’d recommend removing the plugin’s dependency on the rmagick gem - I’m not sure I see where that gem is being called as it looks like it’s extending core Discourse’s optimize image calls, which just calls out to the imagemagick binary directly.