A container image is a tar file containing tar files. Each of the tar file is a layer. Once all tar files have been extract into the same location then you have the container's filesystem.
docker pull pythonrocks/chat-carbon:1.0.0
Export the image into the raw tar format.
docker save -o chat.tar pythonrocks/chat-carbon:1.0.0
tar xvf chat.tar
The image also includes metadata about the image, such as version information and tag names. install jq if needed.
cat repositories | jq .
cat manifest.json | jq .
Extracting a layer will show you which files that layer provides.
tar xvf 2822671d0cf9e5ef8f60a47d2caac3446467387df22e240b23311a9a44c40721/layer.tar
Create an empty image
tar cv --files-from /dev/null | docker import - empty
docker images