Hosting a repository
Flathub uses flat-manager to host its Flatpak repository. See https://github.com/flatpak/flat-manager
The section on :doc:`flatpak-builder` describes how to generate repositories. The resulting repository can be hosted on a web server for consumption by users.
Flatpak repositories use archive-z2, meaning that they contain a single file for each file in the application. This means that pull operations involve a lot of HTTP requests. Since new requests can be slow, it is important to enable HTTP keep-alive on the web server that is hosting your repository.
Flatpak supports something called static deltas. These are single files that
contain all the data needed to go between two revisions (or from nothing to
a revision). Creating such deltas will take up more space on the server,
but will make downloads much faster. This can be done with the
build-update-repo --generate-static-deltas option.
.flatpakrepo files are a convenient way to let users add a
repository. These are simple description files which contain information
about the repository. For example, the Flathub repo file looks like:
[Flatpak Repo] Title=Flathub Url=https://dl.flathub.org/repo/ Homepage=https://flathub.org/ Comment=Central repository of Flatpak applications Description=Central repository of Flatpak applications Icon=https://dl.flathub.org/repo/logo.svg GPGKey=mQINBFlD2sABEADsiUZUO...
Here you can see that the repo file contains descriptive metadata, such as the repository name, description, icon and website. The file also contains information that is needed to add the repository, including a download URL and the repository's GPG key.
.flatpakrepo files can be used to add a repository from the command
line. For example, the command to add Flathub using its repo file is:
$ flatpak remote-add --if-not-exists flathub https://dl.flathub.org/repo/flathub.flatpakrepo
The command line isn't the only way to add a repository using a
.flatpakrepo file - on desktops that support Flatpak, it is just a matter
of clicking the repository file or a download link that points to it.
.flatpakrepo files should include the base64-encoded version of the
GPG key that was used to sign the repository. This can be obtained with
the following command:
$ base64 --wrap=0 < key.gpg