bug#72061: Discrepancy when running ‘guix pull’ from different machines

[Simon Tournier <zimon.toutoune@gmail.com>]

Hi Ludo,

Thank you for the pedestrian report; I have learnt new stuff! :-)


On Thu, 11 Jul 2024 at 17:33, Ludovic Courtès <ludo@gnu.org> wrote:

> Presumably whether ‘builtin:git-download’ is used changes the DAG
> traversal order, which could explain this discrepancy.
>
> It does mean that all the users running an old guix-daemon find
> themselves having no substitutes for ‘guix pull’.  Ouch.

Is it not only for grafts?


Well, in addition, some input derivations are not the same:

--8<---------------cut here---------------start------------->8---
2 candidates:
./fy39r2y8dg2ycdzvnbqyfd1kpandnpxb-avahi-0.8.drv:3: ,[("/gnu/store/0q4nrqmh6ymhs4hmg9vmxa8zqx1y3d2z-dbus-1.14.0.drv",["out"])
./fy39r2y8dg2ycdzvnbqyfd1kpandnpxb-avahi-0.8.drv:18:   ,("/gnu/store/fflyi1qg7j9kz0b062p6xf0904rc8xkm-dbus-1.14.0.drv",["out"])
--8<---------------cut here---------------end--------------->8---

compared to:

--8<---------------cut here---------------start------------->8---
2 candidates:
./vhj8f01bwddshnc75ar5z62ndcij4pgy-avahi-0.8.drv:9:   ,("/gnu/store/6p17vdziv9vcp8l4c8v0xqj855gf257g-dbus-1.14.0.drv",["out"])
./vhj8f01bwddshnc75ar5z62ndcij4pgy-avahi-0.8.drv:17:   ,("/gnu/store/j6g0pchbj39pbg9b9bh7wafsd8kysvv3-dbus-1.14.0.drv",["out"])
--8<---------------cut here---------------end--------------->8---

Although the two derivations:

    /gnu/store/0q4nrqmh6ymhs4hmg9vmxa8zqx1y3d2z-dbus-1.14.0.drv
    /gnu/store/6p17vdziv9vcp8l4c8v0xqj855gf257g-dbus-1.14.0.drv

builds: /gnu/store/hjc4rdifbl890j03xy2gsa7y2sqcg0mi-dbus-1.14.0.

And similarly for the two others ’dbus’ derivations; they build the same
outputs.

Please also note that the two derivations do not have the same order for
the builder part:

--8<---------------cut here---------------start------------->8---
,["/gnu/store/32kpijl743qn7v337i19dd1hph1rd6x7-avahi-0.8-builder","/gnu/store/a6acf6dds8s9fw7dp5div03rwik0x4x2-module-import"]
,["/gnu/store/a6acf6dds8s9fw7dp5div03rwik0x4x2-module-import","/gnu/store/z1kanbslzb2lrr1hj922a50zkxl9jz28-avahi-0.8-builder"]
--8<---------------cut here---------------end--------------->8---

And the two builder scripts are not the same because the item
"/gnu/store/36my0g0j72b3vbz0gj1l8f0lmmgfkv3w-glib-2.72.3" is line 26 for
one and line 30 for the other.


Cheers,
simon