What if I used an bare image, installed some stuff and can't remember what all I did to get it in a usable state for my application.

I wish it could automatically create a Dockerfile for me.

See ‘docker container commit’ [0]

> Create a new image from a [running] container's changes

You might then be able to run ‘docker image history’ [1] to get the changes, which you might be able to write into your own Dockerfile [2]

but I’ve never tested this workflow because the best practice is just to write a Dockerfile first

The tool (docker) was designed in a specific way, learn how to use the tool’s workflow instead of wishing for a different workflow and you’ll have a much easier time.

[0]: https://docs.docker.com/reference/cli/docker/container/commi...

[1]: https://docs.docker.com/reference/cli/docker/image/history/

[2]: can’t remember how docker tracks internal container file system changes and whether the history command will pick them up

Edit — see sibling comment https://news.ycombinator.com/item?id=41371867 — basically… learn to build a dockerfile (they’re very simple and easy once you know how).

``` tail .zsh_history > setup.sh echo COPY setup.sh >> Dockerfile echo RUN ./setup.sh >> Dockerfile ```

you can but it's not recommended because it's basically impossible to audit changes made and is unrepeatable

https://stackoverflow.com/a/46917993/89373