Hi,
I have a proposal for a new way handling of %mirrors from (guix download) and possibly other things. Few months ago there was a misbehaving mirror in the %mirrors that didn't send 404 for missing pages. It meant users got html pages instead of source. This issue was fixed by removing the mirror from %mirrors, but it fixes it only if you are using newer Guix that has it removed. Still if you go back in time, you can face an issue as long as you don't use substitutes. Because of possibility of such issues I have a proposal, to still have %mirrors in Guix code, but only as a default. And to try to load system or user module where the users or system administrators can configure new mirrors. Specifically I am imagining something like /etc/guix/config.scm and ~/.config/guix/config.scm. This module could export %mirrors, but if it didn't, the deafult would be used. Then on Guix System this could exist by default in the system and by default have what is in the Guix source that built the system. This way if users on Guix System go back in time through time machine and face misbehaving mirrors (but of course only those with handling of this new config), they are safe even with time-machine going back. Misbehaving mirrors is the initial motivation, but I think it doesn't have to be the only reason for this change. Users could also choose mirrors closer to them. If this change has been agreed upon, %disarchive-mirrors should probably have the same handling, and I presume %swh-base-url (though that one is at least parameterizable, but still, you cannot really change it if you use the regular guix scripts) could also be useful. Or in general pretty much every url that the user cannot really change without rebuilding guix? For example with packages, you can still inherit them, use transformations etc., but with overriding mirrors, you are out of luck. While we might not see this as necessary at this current moment, we cannot know what the future will bring and if we need to change the urls, time-machine's behavior will become inferior when coming back in time as the users will start facing issues that led to the change of the given url in the first place. This sort of future-proofs Guix. What do you think? Rutherther
