[PureOS] Using SOURCE_DATE_EPOCH env var in PureOS builds

[Chris Lamb]

Hi Jeremiah,
 
> I impatiently added the SOURCE_DATE_EPOCH to the version of make-live
> that we use to build PureOS images. It seems to have made a difference
[…]
> The leads me to believe that I need to ensure that SOURCE_DATE_EPOCH is
> being seen when the squashfs file system is written

This is somewhat of non-sequitur to my ears — if it made any
difference it surely is being seen in the "last mile" and thus
relevant build context? (Regardless, sprinkling in a few debug
statements makes sense just as a reassurance so I would go ahead and
do this anyway.)

> After that I think the next step, or even a step to take anyway, is to
> run strip-nondeterminism over the resulting ISOs[1.]

Alas, we would part ways here in that I would be against running this.
I doubt that would have the desired effect and nor would be a clean
and sustainable route going forward.

To elaborate, strip-nondeterminism is not a clairvoyant magic wand for
cleaning stuff up, it's more of a surgical strike against quite-
specific problems that are currently out-of-scope for me to fix in
upstream toolchains right now. That is to say, in an ideal world the
tool would be deprecated and removed. Give us time. :)

Just glancing at the diff in order that you can get another "go" at
this before the start of the weekend: my gut feel is that we are
building with versions of tools that do not have various patches
designed to make various outputs reproducible. (Just as use one
relevant example, I have made patches to mksquashfs and casper that
may not be present in the versions you are using.)

This may (or may not…) be in addition to the aforementioned
SOURCE_DATE_EPOCH not being present in the right contexts....


Best wishes,

-- 
Chris Lamb
https://puri.sm