How do I find out which flatpak sdk provides a certain library?

I'm trying my hand at packaging an application using flatpak. The metadata is pretty simple at the moment:

[Application]
name=io.brackets.App
runtime=org.gnome.Platform/x86_64/3.20
sdk=org.gnome.Sdk/x86_64/3.20
command=brackets

The application depends on certain libraries not contained in the sdk, as it fails at runtime:

/app/bin/brackets: error while loading shared libraries: libgconf-2.so.4: cannot open shared object file: No such file or directory

I know how to find out the proper runtime in RPM land, but how do I find out what provides these libraries in flatpak?

Solution

Since GConf has been deprecated since (IIRC) the first release of Gnome 3, it's not in the Gnome runtime. You'll have to bundle it.

Using flatpak-builder this will end up as a module similar to the following

    {
        "name": "gconf",
        "config-opts": ["--disable-orbit"],
        "sources" : [
            {
                "type": "archive",
                "url": "http://ftp.gnome.org/pub/GNOME/sources/GConf/3.2/GConf-3.2.6.tar.xz",
                "sha256": "1912b91803ab09a5eed34d364bf09fe3a2a9c96751fde03a4e0cfa51a04d784c"
            }
        ]
    }

An example of this can be found in the spotify flatpak wrapper