Re: unexpected reproducibility of reproducible blog post?

[zimoun]

Hi Leo,

Thank you for testing.


On Mon, 27 Apr 2020 at 00:53, Leo Prikler <address@hidden> wrote:

> yours: /gnu/store/klisfr3a4wxb9dc5sgibb45kky72kg65-docker-pack.tar
> mine:  /gnu/store/klisfr3a4wxb9dc5sgibb45kky72kg65-docker-pack.tar

Nice!

What is your "guix describe"?


> I don't know, what configuration exactly went into the blog post, but I
> assume, it is not the same as for the time-machine experiments before.
> Since the prefix `guix time-machine --channels=guix-version-for-
> reproduction.txt --` appears to be missing from the command, that hash
> is therefore probably not indicative of anything.

I do not know. That's why I am asking. :-)
Because when reading the blog post, I naively assume that all had been
run with the same version of Guix and the post mentions only one
commit. Well, if it is not the case, it should be mentioned in the
blog post because it is currently misleading, IMO.


> I think the larger problem here is that, while Guix itself is
> reproducible, Guix + org-mode (specifically the latter) is not.

Why?


> Particularly, looking at the source[1,2], it appears as if all code
> blocks were evaluated once, but evaluating them again in a new
> environment would bring different results.

Do you mean evaluate twice in a row leads to different results?
By results, I mean items in '/gnu/store'.
Because, yes the org-babel cache should not be reproducible. But that
another story and should not impact the result of a source block.


> In other words, you'd have
> to use `guix time-machine` inside `guix time-machine` to get a truly
> reproducibly org-mode file, or else come up with a smart way of
> dynamically updating the hash in the source blocks themselves.

I do not know and I am not sure to follow.


My point is:
 - only one Guix commit is provided by the post, so it seems
legitimate to assume this commit had been used for all the post
 - using this commit leads to different item in the store

The question is why?
 - another commit had been used. Which one? Could be mentioned in the post?
 - or there is something unexpected and let inspect what.


All the best,
simon