How to debug intermittent font/text rendering issue?

[NiklasBr]

All tips on debugging this issue are very welcome!

Every so often a PDF generated with Gotenberg 8 will lack all fonts loaded with CSS @font-face { font-family: ... for the text. It will otherwise have rendered properly, as seen here:

Output is reported as:

PDF Producer: Skia/PDF m122
PDF Version: 1.4 

We tried implementing waitForExpression as 'document.readyState === "complete"'. We tried window.status as mentioned in the docs, but it did not change anything (and it is apparently deprecated anyway).

We also tried a dumb regular waitDelay but it also had no effect.

Trying to reproduce it on the very same data/request a few minutes later will often lead to a fully working PDF with the fonts and everything 100% as expected:

[gulien]

Hey @NiklasBr 👋

Could you share the requests for both documents? My first supposition is that you’re using skipNetworkIdleEvent 🤔

[gulien]

No idea what's going on 🤔 Chromium should wait for all assets to be loaded. Do you see anything on the debug logs?
If you use a "standard" font like Arial, does it work every time?

[NiklasBr]

It seems standard fonts work, the header and footer are both using font-family: 'Helvetica Neue', Helvetica, Roboto, Arial, sans-serif;

I suppose a workaround could be to rebuild the Docker container like so: https://gotenberg.dev/docs/configuration#fonts but unfortunately I only have WOFF/WOFF2 files at the moment and not TTF.

Any detailed logging we could enable?

[gulien]

I suppose a workaround could be to rebuild the Docker container

That would definitely help 👍

You could use —log-level=debug to check if yours fonts are correctly loaded in Chromium.

[NiklasBr]

Where should I expect logs be stored? Can't find any in /var/logs in the running container

[gulien]

On the Docker logs directly!