Bookmarking/Embedding doesn’t work for self-managed GitLab EE

Hi fellow developers,

I’m running a website using Ghost as the CMS. I’m also maintaining a self-managed instance of GitLab (Enterprise Edition v16.8).

Ghost comes with some features to easily style content and integrate with multiple services, such as the /bookmark feature. This automatically visualizes links to other websites. However, this doesn’t seem to work for my self-managed GitLab instance. Since /bookmark works for GitHub, I checked GitLab SaaS too and SaaS seems to work too. This would mean it’s probably caused by my own configuration.

I was assuming it would be related to some CSP and/or CORS setting, however a little expermenting with the available settings in the /etc/gitlab/gitlab.rb file didn’t seem to do the trick.

It’s not particularly a urgent question, but since I couldn’t find a fix myself, I figured I might still find a solution in the community.

It might be relevant to add that my website and my GitLab instance are both within the same domain. My website uses www.example.com and my GitLab instance uses gitlab.example.com.

I added the screenshot as an afterthought, to visualize what I mean with /bookmark. Even though I made the screenshot on a mobile device, there is no difference with desktop devices.