You need to use xdg-desktop-portals as well as gnomes backend for it so that metadata cleaner can access your files. This is a paper cut that shouldn't exist (xdg-desktop-portals should be installed alongside any distro that has flatpak, or made a dependency of flatpak when you are installing) but metadata cleaner does not need flatseal to work, and it was never intended to use filesystem=host in the first place.
We are not seeking a solution for the problem. You can solve the issue with one command line if you desire, but we are talking about the default UX from the perspective of a new user. Neither Debian nor Ubuntu have their Flatpak package depending on the xdg-desktop-portal package (and by extend ~70% of Linux desktop users including every Deb-based distro), so when the user installs Flatpak, his/her system will not have that package installed by default.
If you are asking that the user should figure it out on his/her own, then here goes another UX hurdle that shouldn't have happened in the first place. Flatpak devs should have communicated with distro developers and requested that this package becomes a dependency for their software, and not let users simply fight with it on their own.
Additionally, the same happens if you install Flatpak from the official PPA provided by the Flatpak project: https://flatpak.org/setup/Ubuntu, even their version does not depend on that package... So how is the user supposed to behave?
For all of the distributions you just mentioned including the PPA have both xdg-desktop-portal as well as xdg-desktop-portal-gtk (Or another already installed backend) marked as recommended.
By default apt (on debian and ubuntu) automatically installs recommended dependencies, thus most of said "~70% of Linux desktop users" should without issue get both flatpak and its portals.
Maybe it would be useful to go into more depth on how the host system used in the article is configured, so as to add some context and possibly solve the actual problem occurring.
Nope, apt does not install recommended dependencies automatically for all the packages. The default "install" command for Flatpak package will just install the package and its dependencies, and you can try this on a fresh Debian or Ubuntu if you like (e.g sudo apt install flatpak). If you want the recommended packages then you have to attach the "--install-suggests" flag to the command, which is not a default experience either, nor mentioned even in the Flatpak installation page.
Edit: In any case, we want to add that the software should emphasize whether or not additional permissions/packages are needed. Whether the package is getting installed or not marked for installation for some reason, it doesn't remove the app's responsibility/Flatpak responsibility to at least mention the existence of the entire thing somewhere.
I agree in the idea that flatpak in, the at least seemingly rare, case of the portal frontend not being available it should probably warn the user.
But this really this is not at the level of urgency the article implies. Where "tens or even hundreds" of applications somehow broken by default everywhere.
Good catch. Indeed many Linux distributions do have it by default it seems, but it is still possible to arrive to situations where it doesn't exist while Flatpak is still there, where it would have been better to make a dependency. We'll update the post accordingly.
You need to use xdg-desktop-portals as well as gnomes backend for it so that metadata cleaner can access your files. This is a paper cut that shouldn't exist (xdg-desktop-portals should be installed alongside any distro that has flatpak, or made a dependency of flatpak when you are installing) but metadata cleaner does not need flatseal to work, and it was never intended to use filesystem=host in the first place.
We are not seeking a solution for the problem. You can solve the issue with one command line if you desire, but we are talking about the default UX from the perspective of a new user. Neither Debian nor Ubuntu have their Flatpak package depending on the xdg-desktop-portal package (and by extend ~70% of Linux desktop users including every Deb-based distro), so when the user installs Flatpak, his/her system will not have that package installed by default.
If you are asking that the user should figure it out on his/her own, then here goes another UX hurdle that shouldn't have happened in the first place. Flatpak devs should have communicated with distro developers and requested that this package becomes a dependency for their software, and not let users simply fight with it on their own.
Additionally, the same happens if you install Flatpak from the official PPA provided by the Flatpak project: https://flatpak.org/setup/Ubuntu, even their version does not depend on that package... So how is the user supposed to behave?
For all of the distributions you just mentioned including the PPA have both xdg-desktop-portal as well as xdg-desktop-portal-gtk (Or another already installed backend) marked as recommended.
By default apt (on debian and ubuntu) automatically installs recommended dependencies, thus most of said "~70% of Linux desktop users" should without issue get both flatpak and its portals.
Maybe it would be useful to go into more depth on how the host system used in the article is configured, so as to add some context and possibly solve the actual problem occurring.
Nope, apt does not install recommended dependencies automatically for all the packages. The default "install" command for Flatpak package will just install the package and its dependencies, and you can try this on a fresh Debian or Ubuntu if you like (e.g sudo apt install flatpak). If you want the recommended packages then you have to attach the "--install-suggests" flag to the command, which is not a default experience either, nor mentioned even in the Flatpak installation page.
Edit: In any case, we want to add that the software should emphasize whether or not additional permissions/packages are needed. Whether the package is getting installed or not marked for installation for some reason, it doesn't remove the app's responsibility/Flatpak responsibility to at least mention the existence of the entire thing somewhere.
I agree in the idea that flatpak in, the at least seemingly rare, case of the portal frontend not being available it should probably warn the user.
But this really this is not at the level of urgency the article implies. Where "tens or even hundreds" of applications somehow broken by default everywhere.
Good catch. Indeed many Linux distributions do have it by default it seems, but it is still possible to arrive to situations where it doesn't exist while Flatpak is still there, where it would have been better to make a dependency. We'll update the post accordingly.
Thanks for the tip!
Recommend and Suggests are two separate things.
The semantic (is that the right word?) differences can be found here:
https://www.debian.org/doc/debian-policy/ch-relationships.html#binary-dependencies-depends-recommends-suggests-enhances-pre-depends
Suggests are indeed not installed by default. I don't blame you for confusing them I did too for a while.
As for ubuntu 22.04, the portals are installed by default as they are already used by snap.
Could you point out the distro you were using to test, in the article? At least we can then identify what cause the issue there, and try to fix it.