DNT (Do Not Track) header detection not working when caching enabled

I have opened a MR that removes the custom caching of eu_cookie_compliance_build_data() and adds the DNT header to the cache context of eu_cookie_compliance_page_attachments(). Default services (default.services.yml) already has the language and theme cache contexts. And the Domain module suggests adding `url.site` to that list.

I did not see any existing tests for this module, and even if I did, testing this seems pretty difficult. So I'll simply mark this for needing review and let others test it out.

Not that i'm an expert in caching, but we might have to put some of the caching context back.
Keep the Language, and theme out, since it's done in the services file already, and leave in the domain module check? This will leave specific domain caching intact?

Thoughts?

@atowl regarding the domain cache context, the domain module documentation suggests adding url.site to the services file. So users of that module should follow its directions, as doing so will resolve all sorts of things. If domain module users are experiencing issues with this module, it's not due to this module but rather not properly configuring their site for the domain module.

Hi!

Thanks for helping.

Could you please explain the reason for the removal of line 156-179?

@svenryen In summary, I'm questioning the work done on #3015612: [1.x][2.0.x] Better caching for cookie performance popup → and proposing that we undo it. I do not understand why that task says we cannot use the render cache. I will move my discussion to that task.

Side note: DNT is afaik dead: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/DNT. There seems to be a replacement that probably needs similar treatment though.

So just to continue on the conversation that @berdir has kicked off, if headers:DNT is now deprecated, what do we put there instead?

While I don't see an issue in continuing with this patch at present, but just wondered if there was something else to put in? at the same time, or maybe we create a new issue and deal with it there.

@atowl I have created a separate task for removing the custom cache entry ( 📌 Remove custom eu_cookie_compliance_data cache entry Active ) and will close this one as "won't fix".

Hi @pianomansam,

Great idea. Thanks.