Docker history

Each Docker image is built by layers upon layers.

The docker history command can show you these layers.

docker history IMAGE

Here you can see that the Ubuntu image we have downloaded from the Docker Hub has 5 layers.

$ docker history ubuntu:20.04

IMAGE               CREATED             CREATED BY                                      SIZE
74435f89ab78        4 weeks ago         /bin/sh -c #(nop)  CMD ["/bin/bash"]            0B
<missing>           4 weeks ago         /bin/sh -c mkdir -p /run/systemd && echo 'do…   7B
<missing>           4 weeks ago         /bin/sh -c set -xe   && echo '#!/bin/sh' > /…   811B
<missing>           4 weeks ago         /bin/sh -c [ -z "$(apt-get indextargets)" ]     1.01MB
<missing>           4 weeks ago         /bin/sh -c #(nop) ADD file:b2342c7e6665d5ff3…   72.8MB