This honors the following environment variables:
- $GPG_KEY_ID: When set, it can be the identifier, full fingerprint, or
email address of a GnuPG key which will be used to sign Flatpak builds.
- $GPG_HOMEDIR: Path to an alternative home directory to be used by GnuPG,
instead of the default ~/.gnupg directory of the current user. This can
be used to point GnuPG to a different keychain.
This makes the Flatpak builds honor the $FLATPAK_REPO environment variable.
When it is defined, it will be used as the path to an OSTree repository where
the Flatpak application bundle will be committed to. This allows to place
multiple builds in the same repository (along other applications, even), which
can be published. For more details abuit using repositories for publishing,
Note that setting $FLATPAK_REPO disables building a standalone .flatpak bundle
When storing the output of a Flatpak build to a commit into an OSTree
repository (by setting the $FLATPAK_REPO environment variable), it is
good to have a descriptive subject in the commit log message.