Docker save only non public layers

Question

I can export images with

docker save -o <save image to path> <image name>

but this will pack all layers, and the file is big

is there a possibility to pack only layers which are not public available, so only the difference to the last public layer is exported?

Answer 1

The docker-save-last-layer command line utility combined with docker build --squash is made to accomplish exactly this.

It exports only the last layer of the specified docker image.

It works by using a patched version of the docker daemon inside a docker image that can access the images on your host machine. So it doesn't require doing a full docker save before using it like the undocker answer. This makes it much more performant for large base images.

Typical usage is simple and looks like:

pip install d-save-last

docker build --t myimage --squash .
d-save-last myimage -o ./myimage.tar