How does a Docker container handle certificates

Hello Community

My first post is about a comprehension question. Nextcloud is installed on my Unraid system as a Docker from the repository. When I now open the Nextcloud via web browser, I get the message “The server certificate is not trusted” with execute anyway I can log in normally. If I display the certificate in the menu bar at the top of the web browser, it is certificate. Here are my questions. Where exactly in Docker can I find this certificate and check when it was installed?

Why am I asking this? A few days ago I wanted to mount Unraid Share which is integrated as an external device in Necloud via WebDAV. During the mount I received the message “The server certificate does not match the name of the server, we do not trust the certificate”. Issuer and owner was LSIO Server, The fingerprint should be checked. The fingerprint was different from the one I can see in the address bar in the web browser. I accepted the certificate anyway, but now I have to accept it again with every mount.

My question is, how can I accept this certificate permanently and where can I see the assignment to the Docker container? Where is the certificate for the WebDAV share stored? On my Linux client? How could I have checked the fingerprint beforehand?

Based on my question, you can see that I don’t understand how to handle the Nextclaoud Docker container in general when dealing with the certificates. Can someone please help me shed some light on this. Neither the Unraid, Nextcloud nor Ubuntu forum could give me an answer to these questions.

Thanks in advance.