fontconfig: Stop using versioned config dirs #95358

jtojnar · 2020-08-13T17:21:51Z

Motivation for this change

Turns out lot of software (including Chromium) use bundled fontconfig so we either need to wrap every one of those, or re-introduce the global unversioned config. The latter is easier but weakens hermetic configs.

But perhaps those are not really worth the effort. Given that programs linked against fc 2.12.6 on fc 2.13.92 system seem to at least display text, even while printing tons of errors (as long as you generate fc cache manually), and same thing the other way around, hopefully it will not be an issue in the future. If we give up on the hermetic configs, we can get rid of lot of complexity (see the diff).

Links

fontconfig MR improving the severity of unrelated compat warnings: https://gitlab.freedesktop.org/fontconfig/fontconfig/-/merge_requests/111
https://logs.nix.samueldr.com/nixos-dev/2020-08-13#1597332919-1597339347;

Things done

jtojnar · 2020-08-13T18:35:44Z

Let’s fix the chromium in master first: #95362

flokli · 2020-08-13T19:16:52Z

#95362 was merged, so master should be fixed.

jtojnar · 2020-08-13T20:14:01Z

I am completely convinced this is the way to go.

flokli · 2020-08-13T21:37:26Z

pkgs/development/libraries/fontconfig/default.nix

+    # Don't try to write to /var/cache/fontconfig at install time.
+    "fc_cachedir=$(TMPDIR)/dummy"
+    "RUN_FC_CACHE_TEST=false"
+    "sysconfdir=${placeholder "out"}/etc"


Do we need to set sysconfdir for both install and configure?

Yes, the configure makes /etc hardcoded into the code but we cannot install to /etc so we need to move the installation path into the derivation. It is quite common idiom.

flokli · 2020-08-17T21:16:29Z

We might need to merge #95716 first (and then rebase this PR on top of master)

flokli · 2020-08-26T22:57:56Z

@jtojnar can this be rebased?

This reverts commit edf2541. Turns out lot of software (including Chromium) use bundled fontconfig so we either need to wrap every one of those, or re-introduce the global unversioned config. The latter is easier but weakens hermetic configs. But perhaps those are not really worth the effort. Given that programs linked against fc 2.12.6 on fc 2.13.92 system seem to at least display text, even while printing tons of errors (as long as you generate fc cache manually), and same thing the other way around, hopefully it will not be an issue in the future. We give up on the hermetic configs in exchange for getting rid of lot of complexity.

The incompatibility does not seem to exist any more: programs linked against fc 2.12 on fc 2.14 system seem to at least display text, even while printing tons of errors (as long as you generate fc cache manually), and same thing the other way around. Hopefully it will not be an issue in the future.

jtojnar · 2020-08-29T17:20:34Z

Rebased.

worldofpeace · 2020-08-31T14:38:37Z

@jtojnar I think we should document the fontconfig changes in the release notes eventually.

edolstra · 2020-08-31T14:46:41Z

Not convinced this is a good idea. What are we going to do when fontconfig changes in a backwards-incompatible way again in the future?

jtojnar · 2020-09-03T06:54:05Z

The versioned config was introduced in 0927405 and c0e2ace (#4410) to resolve #2050, there were also some issues with xml:space b16994f

Looking at the changes in #4410 (comment) it was really just minor relaxation of the schema. The unknown elements would already be skipped with a warning and the patch I sent upstream changes the unknown attributes severity to warning as well (and they were already ignored previously). For that reason backwards compatibility should not be an issue – the configs will continue to be parsed unless they change the format drastically, which is pretty unlikely with the upstream development pace. Forwards compatibility should not be an issue for the same reason.

Outside of NixOS, we would use the unversioned config in either case so nothing changes there.

jtojnar · 2020-09-03T07:01:32Z

The only other reason why we might still want to have versioning is to generate cache for multiple fontconfig versions declaratively but we are not really supporting multiple versions any way. And we could do that in a single config and fontconfig should ignore the cache files generated by other versions.

The use of the argument was removed in 2016 but its definition was left behind. NixOS@cd2948a

jtojnar · 2020-09-04T22:19:33Z

Merging after IRC discussion with RM.

vcunat · 2020-09-05T16:08:12Z

I wanted to try some tests on latest staging-next

nix build -f nixos/release-combined.nix nixos.tests.installer.swraid.x86_64-linux

but got blocked by

builder for '/nix/store/HASH1-fontconfig-conf.drv' failed with exit code 1; last 1 log lines:
  ln: failed to create symbolic link '/nix/store/HASH2-fontconfig-conf/etc/fonts/conf.d/50-user.conf': File exists

You'll probably know way faster than me.

flokli · 2020-09-05T21:04:23Z

pkgs/development/libraries/fontconfig/default.nix

      --path $out/share/xml/fontconfig \
      ${./make-fonts-conf.xsl} $out/etc/fonts/fonts.conf \
      > fonts.conf.tmp
    mv fonts.conf.tmp $out/etc/fonts/fonts.conf
-
-    # Make it easier to remove user config in NixOS module.


@vcunat this probably should have been kept?

(or https://github.com/NixOS/nixpkgs/pull/95358/files#diff-376672cba12c87d4103e6134632e306fR203 remove the symlink in case cfg.includeUserConf is false?

I forgot to revert also 8425726.

This reverts commit 8425726. This should have been reverted in #95358 but I forgot about it.

jtojnar · 2020-09-06T01:00:29Z

Should be fixed by f0cb5c6.

nixos-discourse · 2021-05-24T18:54:14Z

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/nixos-builds-a-ton-of-packages-instead-of-fetching-them-in-the-cache/13231/8

jtojnar marked this pull request as draft August 13, 2020 17:27

ofborg bot requested a review from vcunat August 13, 2020 18:07

ofborg bot added 10.rebuild-darwin: 501+ 10.rebuild-darwin: 1001-2500 10.rebuild-linux: 501+ 10.rebuild-linux: 5001+ labels Aug 13, 2020

jtojnar requested a review from flokli August 13, 2020 18:30

jtojnar marked this pull request as ready for review August 13, 2020 18:31

jtojnar marked this pull request as draft August 13, 2020 18:54

ofborg bot added 6.topic: nixos Issues or PRs affecting NixOS modules, or package usability issues specific to NixOS 8.has: module (update) This PR changes an existing module in `nixos/` labels Aug 13, 2020

jtojnar force-pushed the global-fontconfig branch from 929199c to 39e8025 Compare August 13, 2020 20:02

flokli reviewed Aug 16, 2020

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flokli marked this pull request as ready for review August 16, 2020 13:08

jtojnar added 2 commits August 29, 2020 19:15

jtojnar force-pushed the global-fontconfig branch from 39e8025 to b49a769 Compare August 29, 2020 17:20

worldofpeace approved these changes Aug 31, 2020

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worldofpeace added this to the 20.09 milestone Aug 31, 2020

worldofpeace mentioned this pull request Aug 31, 2020

20.09 Release notes #95765

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jtojnar mentioned this pull request Sep 3, 2020

fontconfig: Enable color emoji as a fallback #86601

Closed

makeFontsConf: clean up

6f96063

The use of the argument was removed in 2016 but its definition was left behind. NixOS@cd2948a

jtojnar merged commit 4f0f267 into NixOS:staging Sep 4, 2020

jtojnar deleted the global-fontconfig branch September 4, 2020 22:19

flokli reviewed Sep 5, 2020

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jtojnar added a commit that referenced this pull request Sep 6, 2020

Revert "nixos/fontconfig: fix 50-user.conf handling"

f0cb5c6

This reverts commit 8425726. This should have been reverted in #95358 but I forgot about it.

jtojnar mentioned this pull request Sep 12, 2020

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fontconfig: Stop using versioned config dirs #95358

fontconfig: Stop using versioned config dirs #95358

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nixos-discourse commented May 24, 2021

fontconfig: Stop using versioned config dirs #95358

fontconfig: Stop using versioned config dirs #95358

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jtojnar commented Aug 13, 2020 • edited Loading

Motivation for this change

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