Allow setting the URL for config.sub

[tgross35]

Unfortunately the Savannah server can be a bit flaky. Move the config URL to a variable so it can be set to point to a mirror.

[tgross35]

For context, we use this makefile in rust-lang/rust ci and have had some intermittent failures from Savannah.

[userdocs]

The Savannah git is regularly unreachable and the https://ftpmirror.gnu.org/gnu also goes offline periodically.

I don't understand what this achieves because as far as I understand it, there is no public alternative URL to use here.

All mirrors points to a readme - https://mirror.cyberbits.eu/gnu/config/ with this content

From now on, please fetch new versions of these scripts via the
following URLs:

http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.guess;hb=HEAD
http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.sub;hb=HEAD

Thanks,

Ben Elliston bje@gnu.org

And there are no up to date git mirrors of the config repo that I saw.

So is the URL you used a self hosted / mirrored repo of config? If it is maybe just having point to a local file is the better option?

I don't argue a change here is helpful it's just I've come to the conclusion that if the url is down, just fall back to the last good version of the config.sub and have it stored in the repo itself.

[tgross35]

That's basically correct. The "mirror" could just be your fork of the config repo on GH and then passing the raw link as CONFIG_SUB_URL with the right version, e.g. https://raw.githubusercontent.com/richfelker/musl-cross-make/6f3701d08137496d5aac479e3a3977b5ae993c1f/Makefile for this repo's makefile.

There are certainly other options like keeping the file, but in our case we mirror everything locally for CI anyway so most of that is set up.

[richfelker]

I wonder if we should just drop replacing config.sub except for really old tool versions. I don't think it should be necessary for anything remotely modern. We could just have a make variable to enable replacing it, that's off by default.

[userdocs]

I think that makes sense. Only enable it if there is a problem, which solve the immediate problem of the host being so unreliable. The only option otherwise is some type of self hosting.

But, I think even if you did make this change, still allow users to set the URL as it still allows the self hosting option.

[userdocs]

Reference this related commit - drop config.sub replacement

f5a188a