If I run docker history --no-trunc IMAGE on an image which was built from a Dockerfile like:
FROM scratch
ADD something.tar.xz /
...
I see the following under the CREATED BY column in the last line of the docker history output:
/bin/sh -c #(nop) ADD file:fb0755f94145d1e0a46167faf3b43dba3db9383f4c230217a500a65e01307e27 in /
The part after file: looks like a SHA256 hash of something but it doesn't match the SHA256 of...
- the file referenced in the Dockerfile (
something.tar.xz) - the name of that file or its full path at build time
- the layer digest or any other which I see in the output from any Docker ls/inspect/etc.
So my question is, purely out of interest, what is this the hash of?
Related questions
This question is related but based on the misunderstanding that the ADD file:... is actually in the Dockerfile.
This question kind of implicitly asks my question but the closest to an answer is:
I'm not sure there's a reliable way to translate from the host file or URL to the hash
So I want to explicitly ask the question of what the hash actually refers to, even though I fully understand that I cannot magically reconstitute any information from it about the original file which was ADDed.