@pmiazga your running manually the command should have produced a fonts.conf file. Can you please attach it to this task? For reference, here is the config that has been used for Electron.

<?xml version='1.0'?>
<!DOCTYPE fontconfig SYSTEM 'fonts.dtd'>
<fontconfig>
 <match target="font">
  <edit mode="assign" name="rgba">
   <const>rgb</const>
  </edit>
 </match>
 <match target="font">
  <edit mode="assign" name="hinting">
   <bool>false</bool>
  </edit>
 </match>
 <match target="font">
  <edit mode="assign" name="hintstyle">
   <const>hintslight</const>
  </edit>
 </match>
 <match target="font">
  <edit mode="assign" name="antialias">
   <bool>true</bool>
  </edit>
 </match>
  <match target="font">
    <edit mode="assign" name="lcdfilter">
      <const>lcddefault</const>
    </edit>
  </match>
</fontconfig>

But I'd like to point that the fontconfig-config package created lots of 20-unhint-*.conf files:

lrwxrwxrwx 1 root root   50 Aug 16  2016 20-unhint-small-dejavu-lgc-sans.conf -> ../conf.avail/20-unhint-small-dejavu-lgc-sans.conf
lrwxrwxrwx 1 root root   55 Aug 16  2016 20-unhint-small-dejavu-lgc-sans-mono.conf -> ../conf.avail/20-unhint-small-dejavu-lgc-sans-mono.conf
lrwxrwxrwx 1 root root   51 Aug 16  2016 20-unhint-small-dejavu-lgc-serif.conf -> ../conf.avail/20-unhint-small-dejavu-lgc-serif.conf
lrwxrwxrwx 1 root root   46 Aug 16  2016 20-unhint-small-dejavu-sans.conf -> ../conf.avail/20-unhint-small-dejavu-sans.conf
lrwxrwxrwx 1 root root   51 Aug 16  2016 20-unhint-small-dejavu-sans-mono.conf -> ../conf.avail/20-unhint-small-dejavu-sans-mono.conf
lrwxrwxrwx 1 root root   47 Aug 16  2016 20-unhint-small-dejavu-serif.conf -> ../conf.avail/20-unhint-small-dejavu-serif.conf
lrwxrwxrwx 1 root root   58 Aug 24  2016 20-unhint-small-vera.conf -> /usr/share/fontconfig/conf.avail/20-unhint-small-vera.conf

Everything is available on deployment-chromium01 server (I did all tests there)

In T199264#4416068, @pmiazga wrote:

<?xml version='1.0'?>
<!DOCTYPE fontconfig SYSTEM 'fonts.dtd'>
<fontconfig>
[...]
</fontconfig>

Where is this file? I've tried searching for it on deployment-chromium01 but can't find it.

But I'd like to point that the fontconfig-config package created lots of 20-unhint-*.conf files:

lrwxrwxrwx 1 root root   50 Aug 16  2016 20-unhint-small-dejavu-lgc-sans.conf -> ../conf.avail/20-unhint-small-dejavu-lgc-sans.conf
lrwxrwxrwx 1 root root   55 Aug 16  2016 20-unhint-small-dejavu-lgc-sans-mono.conf -> ../conf.avail/20-unhint-small-dejavu-lgc-sans-mono.conf
lrwxrwxrwx 1 root root   51 Aug 16  2016 20-unhint-small-dejavu-lgc-serif.conf -> ../conf.avail/20-unhint-small-dejavu-lgc-serif.conf
lrwxrwxrwx 1 root root   46 Aug 16  2016 20-unhint-small-dejavu-sans.conf -> ../conf.avail/20-unhint-small-dejavu-sans.conf
lrwxrwxrwx 1 root root   51 Aug 16  2016 20-unhint-small-dejavu-sans-mono.conf -> ../conf.avail/20-unhint-small-dejavu-sans-mono.conf
lrwxrwxrwx 1 root root   47 Aug 16  2016 20-unhint-small-dejavu-serif.conf -> ../conf.avail/20-unhint-small-dejavu-serif.conf
lrwxrwxrwx 1 root root   58 Aug 24  2016 20-unhint-small-vera.conf -> /usr/share/fontconfig/conf.avail/20-unhint-small-vera.conf

Actually, your reconfiguration created only a handful of new symlinks:

lrwxrwxrwx 1 root root   54 Jul  6 19:54 10-sub-pixel-rgb.conf -> /usr/share/fontconfig/conf.avail/10-sub-pixel-rgb.conf
lrwxrwxrwx 1 root root   49 Jul  6 19:54 10-unhinted.conf -> /usr/share/fontconfig/conf.avail/10-unhinted.conf
lrwxrwxrwx 1 root root   52 Jul  6 19:54 70-yes-bitmaps.conf -> /usr/share/fontconfig/conf.avail/70-yes-bitmaps.conf

These might be enough to reproduce in production to get the desired effect.

Those changes were in /etc/fonts/fonts.conf and /etc/fonts/conf.d/51-local.conf but looks like they are overriten.

To get into the state we want to have, we just need to run dpkg-reconfigure fontconfig-config. Task description says which options works the best with the PDF renderer.

Change 468545 had a related patch set uploaded (by Mobrovac; owner: Mobrovac):
[operations/puppet@production] Proton: Configure the fonts

https://gerrit.wikimedia.org/r/468545

Change 468545 merged by Alexandros Kosiaris:
[operations/puppet@production] Proton: Configure the fonts

https://gerrit.wikimedia.org/r/468545

@pmiazga the font changes have been applied. Could you check the output of the PDFs in production now?

@mobrovac sure, will do, I just have a question, how can I get the PDF from production? I know how to get those from Beta Cluster, but I never tried to fetch the PDF from production

In T199264#4686411, @pmiazga wrote:

@mobrovac sure, will do, I just have a question, how can I get the PDF from production? I know how to get those from Beta Cluster, but I never tried to fetch the PDF from production

Use https://{domain}/api/rest_v1/page/pdf/{title}?new_pdf=true

Fonts are ok, PDF looks good and the hinting/kerning is correct. Thanks for fixing the fonts issue.