Favicon setup: "To work correctly over a CDN it must be a png"

awesomerobot · June 13, 2024, 7:41pm

Any CDNs (content delivery networks) you may have configured for hosting files when setting up your site, for example: Configure an S3 compatible object storage provider for uploads

If you aren’t using a CDN like this, then you can likely disregard the message.

The short answer is that Discourse expects a PNG on the backend.

The long answer seems to be related to this comment in the related code, though I’m not familiar with these technical specifics:

github.com

discourse/discourse/blob/main/app/controllers/static_controller.rb#L134-144


      
              rescue URI::Error
                # Do nothing if the URI is invalid
              end
            end
          
            redirect_to destination
          end
          
          FAVICON ||= -"favicon"
          
          # We need to be able to draw our favicon on a canvas, this happens when you enable the feature
          # that draws the notification count on top of favicon (per user default off)
          #
          # With s3 the original upload is going to be stored at s3, we don't have a local copy of the favicon.
          # To allow canvas to work with s3 we are going to need to add special CORS headers and use
          # a special crossorigin hint on the original, this is not easily workable.
          #
          # Forcing all consumers to set magic CORS headers on a CDN is also not workable for us.
          #
          # So we cache the favicon in redis and serve it out real quick with
          # a huge expiry, we also cache these assets in nginx so it is bypassed if needed

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Favicon setup: "To work correctly over a CDN it must be a png"

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