How can I see Dockerfile for each docker image?

I have the following docker images.

$ docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
hello-world         latest              48b5124b2768        2 months ago        1.84 kB
docker/whalesay     latest              6b362a9f73eb        22 months ago       247 MB

Is there a way I can see the Dockerfile of each docker image on my local system?

The answer at Where to see the Dockerfile for a docker image? does not help me because it does not exactly show the Dockerfile but the commands run to create the image. I want the Dockerfile itself.

Solution

As far as I know, no, you can't. Because a Dockerfile is used for building the image, it is not packed with the image itself. That means you should reverse engineer it. You can use docker inspect on an image or container, thus getting some insight and a feel of how it is configured. The layers an image are also visible, since you pull them when you pull a specific image, so that is also no secret.

However, you can usually see the Dockerfile in the repository of the image itself on Dockerhub. I can't say most repositories have Dockerfiles attached, but the most of the repositories I seen do have it.

Different repository maintainers may opt for different ways to document the Dockerfiles. You can see the Dockerfile tab on the repository page if automatic builds are set up. But when multiple parallel versions are available (like for Ubuntu), maintainers usually opt to put links the Dockerfiles for different versions in the description. If you take a look here: https://hub.docker.com/_/ubuntu/, under the "Supported tags" (again, for Ubuntu), you can see there are links to multiple Dockerfiles, for each respective Ubuntu version.