Add support for flatpak's secret portal

[a-andre]

It's currently not possible to use secretstorage inside flatpak without opening a hole for org.freedesktop.secrets. This allows cross application password access.
When using the portal only the application that stored the password can read it.

For details see flatpak/xdg-desktop-portal#359

Thanks

[mitya57]

I think it's out of scope for this project. SecretStorage is specifically a Python binding to Secret Service D-Bus API (as the description says). The portal doesn't implement the full D-Bus interface, it just provides a master secret that the application can use as it wants.

If you need a generic password storage with several backends, there is Python-Keyring project for that. It has a file-based backend, and I think it will be a valid feature request to allow it to use the master secret provided by the portal. If you agree with me, please file an issue against keyrings.alt project (which provides the file-based backend).

[a-andre]

Thanks for clarification and suggesting an alternative.

A libsecret backend for python-keyring would probably be the best solution then. That way the application could use python-keyring only, without adding a switch between libsecret and python-keyring to the application. But it's unlikely to happen.

Since keyrings.alt is not recommend for production use I'll leave it to others to open a feature request there.