Tandoor Flatpak SSL Issues: Self-Hosted & Custom Certificates

Running your own self-hosted instance of Tandoor can be a fantastic way to manage your recipes, offering unparalleled control and privacy. However, when you decide to add an extra layer of security with a custom SSL certificate, especially one issued by your own Certificate Authority (CA), you might run into a few snags, particularly when trying to access it via the Tandoor Flatpak on your desktop. This is exactly the situation one user found themselves in, seeking a solution for a problem that, while not a showstopper, is certainly worth understanding and potentially fixing for a seamless experience. The core of the issue lies in how the Flatpak application, specifically, interacts with your system's or its own trust store for SSL certificates. Let's dive deep into this, exploring the potential causes and possible avenues for resolution.

The Challenge: Custom SSL and Flatpak's Environment

The user in question has set up a self-hosted Tandoor instance, which is a commendable feat in itself, demonstrating a commitment to personalized data management. To secure this instance, they've employed a reverse proxy and a custom SSL certificate signed by their self-run Certificate Authority. The immediate hurdle arises when attempting to connect to this instance using the Tandoor Flatpak on a desktop environment. Even after meticulously importing the root certificate into their Linux machine's trust store, the Flatpak application seems to ignore it. This is a classic case of an application operating in an isolated environment, a hallmark of Flatpak, which can sometimes prevent it from accessing system-wide configurations like certificate authorities. The frustration is compounded when comparing this with other access methods. For instance, the same Tandoor instance works perfectly fine on an Android device, which correctly leverages Android's trust store. Furthermore, the web sign-in, which is noted to use a Chromium engine, also functions without certificate warnings. This suggests that the underlying engine can access certificates, but the specific mechanism within the Flatpak wrapper isn't making that connection effectively. It's a puzzling discrepancy that points towards the intricacies of Flatpak's sandboxing and how it handles external security credentials. The user rightly points out that while the web app remains a viable alternative, understanding and resolving this Flatpak-specific issue could significantly improve the overall user experience for others facing similar setups.

Why Flatpak Isolation Matters for SSL

Flatpak applications are designed with security and consistency in mind, running in isolated environments called sandboxes. This sandboxing is a powerful feature, preventing applications from interfering with each other or the host system. It ensures that an application will behave the same way regardless of the host system's configuration and that it only has access to the resources it explicitly needs. However, this isolation can become a double-edged sword when dealing with system-level configurations like SSL certificates. When you import a root CA certificate into your Linux system's trust store (e.g., by placing it in /etc/pki/ca-trust/source/anchors/ and running update-ca-certificates), you're telling your operating system to trust certificates signed by that CA. Most applications, especially those not running in a sandbox or those designed to integrate deeply with the host, will automatically pick up these system-wide trust settings. But a Flatpak, by default, doesn't automatically inherit these system-wide trust stores. The application inside the sandbox has its own view of the world, which may or may not include the host's certificate store. This is why, even though your desktop as a whole trusts your custom CA, the Tandoor Flatpak might not. It's like having a key to your house (the system's trust store) but being locked out of a specific room (the Flatpak's sandbox) where that key needs to be presented.

Investigating the Chromium Engine Connection

The user's observation that the web sign-in page loads correctly without certificate warnings is a crucial piece of information. They mention it uses a