Dropping gzip-compressed substitutes?

[Ludovic Courtès]

Hello!

I saw in the maintainer meeting minutes the point about substitute
compression.

Back when zstd substitutes were introduced, the idea was to “eventually”
drop gzip substitutes (lzip substitutes remain relevant⁰):

  https://lists.gnu.org/archive/html/guix-devel/2021-03/msg00333.html

It was too early back then but I think we could consider dropping it
after 1.4.0 is out, announcing it in advance.

To those users still running a pre-1.1.0 daemon lacking lzip support¹,
things will just break, or at least they won’t get newer substitutes.
It’s been almost 2 years since 1.1.0 was released though.

But there does seem to be users on foreign distros who never update
their daemon and don’t read news either.  We could have (guix store)
warn when it’s talking to an old daemon, which would give people a
reminder that they need to upgrade.  (That would only work for very old
daemons because the protocol version rarely changes.)

Thoughts?

Ludo’.

⁰ https://guix.gnu.org/en/blog/2021/getting-bytes-to-disk-more-quickly/
¹ https://guix.gnu.org/en/blog/2020/gnu-guix-1.1.0-released/