How to load a map image file into map_server from memory

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Hi, I'm following this tutorial on Keepout zones for Nav2 and I want to load a map file from memory into the nav2_map_server using ROS2 Foxy. I currently have a service which receives KML files and plots them to image messages using Geopandas and CvBridge. Looking through the source code, I found that Nav2 expects a YAML file describing the image path of the map file, which it then loads using Magick. Is there someway of feeding a in-memory BMP/PMG file to nav2_map_server or simulating a file on Python? If not, is there some correct way of creating temporary files for ROS2 to use?