glot-images are the docker images used by glot.io to run code. The images are built using nix which are pinned to a specific nixpkgs commit to create reproducible images. See the overview on how everything is connected.
The code-runner is installed in each image which writes the files inside the container, compiles and runs the code and returns the result as a json payload.
Prebuilt images can be found on Docker Hub. (If nix is unfamiliar you can find some old examples using Dockerfile here)
echo '{
"language": "javascript",
"files": [{
"name": "main.js",
"content": "console.log(\"Hello World!\");"
}]
}' | docker run -i --rm glot/javascript:latest{"stdout":"Hello World!\n","stderr":"","error":""}