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flat-manager serves and maintains a Flatpak repository. You point it at an ostree repository and it will allow Flatpak clients to install apps from the repository over HTTP. Additionally, it has an HTTP API that lets you upload new builds and manage the repository.

Building the server

The server is written in Rust, so you need to have Rust and Cargo installed. Everything works with the stable version of Rust, so you can get it from rustup or your distribution. On Fedora:

sudo dnf install cargo

PostgreSQL is used for the database, so the Postgres client libraries need to be installed first. On Fedora, this is done with:

sudo dnf install postgresql-devel

You also need ostree. On Fedora, this is done with:

sudo dnf install ostree-devel

Then build the server by running:

cargo build

Building the client

flat-manager contains a Python-based client that can be used to talk to the server. To run this, you need Python 3 as well as the aiohttp packages, installed via pip or the distribution packages. On Fedora, this can be installed using:

sudo dnf install python3-aiohttp


flat-manager reads the config.json file on startup in the current directory, although the REPO_CONFIG environment variable can be set to a different file. If you have a .env file in the current directory or one of its parents, it will be read and used to initialize environment variables.

The source repository contains an example.env and an example-config.json that can be used as a basis:

cp example.env .env
cp example-config.json config.json
# edit config.json


flat-manager can be configured to run hook scripts during the upload and publish processes. These are configured per-repository in the config file; see example-config.json.

The publish hook runs in the build directory before a build is published to a main repository. It can modify the build, for example by rewriting the appstream files in the commits. It receives the FLAT_MANAGER_IS_REPUBLISH environment variable, which is true if the publish was triggered by the republish endpoint or false if the publish is part of a build. If the publish is part of the build, the hook also receives the FLAT_MANAGER_BUILD_ID environment variable.

Check scripts are run after a build is uploaded. Builds may not be published unless all checks have passed. The check is marked as failed if the command exits with a nonzero code (or marked as requiring review if "reviewable": true is set).

Check scripts may also set their own status via the flat-manager API, though this will be overridden if the command exits with a nonzero code. To facilitate this, check scripts are run with FLAT_MANAGER_BUILD_ID and FLAT_MANAGER_JOB_ID environment variables to pass to the API. The same endpoint can be used by other systems for manual reviews.


flat-manager uses a PostgreSQL database to store information, and requires you to specify its address in the configuration file. The default example-config.json points this at:

"database-url": "postgres://%2Fvar%2Frun%2Fpostgresql/repo",

This is a database called repo accessed via the default (at least on Fedora) UNIX domain socket. To install and start PostgreSQL, do something like:

sudo dnf install postgresql-server postgresql-contrib
sudo systemctl enable postgresql
sudo postgresql-setup --initdb --unit postgresql
sudo systemctl start postgresql

On Debian-based systems:

sudo apt install postgresql

And create the repo database owned by your user:

sudo -u postgres createuser $(whoami)
sudo -u postgres createdb --owner=$(whoami) repo

Note that if you're doing development work, it is important to also have DATABASE_URL=... set in the .env file for the Diesel command-line application to work. This is not required in production though.


flat-manager maintains a set of repositories specified in the configuration, as well as a set of dynamically generated repositories beneath the configured build-repo-base path. For testing with the example configuration, these can be initialized by doing:

ostree --repo=repo init --mode=archive-z2
ostree --repo=beta-repo init --mode=archive-z2
mkdir build-repo

On a deployed system, these should be stored elsewhere, but make sure they are on the same filesystem so that hardlinks work between them as otherwise performance will be degraded.


All requests to the API require a token. Token are signed with a secret that has to be stored on the server. The default configuration contains:

"secret": "c2VjcmV0"

This is base64 of "secret", so don't use this in production, but it works for local testing. Otherwise, you can generate one based on some random data:

dd bs=256 count=1 if=/dev/random of=/dev/stdout | base64 -w 0

Each token can have various levels of privileges. For example one could let you do everything, while another would only allow you to upload builds to a particular build. There is an API to subset your token for sharing with others (for example sending the above upload-only token to a builder), but you can also generate a token with the gentoken command:

echo -n "secret" | base64 | cargo run --bin gentoken -- --base64 --secret-file - --name testtoken

The above matches the default secret, so can be used for testing.

Some token privileges are for managing flat-manager and shouldn't be given to third parties who are just uploading apps. The token privileges are described in the ClaimsScope enum in

The client takes tokens via either the --token argument or in the REPO_TOKEN environment variable.

For a production setup, you will also want to generate a token for delta-generator. This can be done by following the above command with these arguments:

echo -n "secret" | base64 | cargo run --bin gentoken -- --base64 --secret-file - --name delta-generator --sub delta --scope generate


To start the server, run:

cargo run --bin flat-manager

It will listen on port 8080 by default.

To test adding something to the repository, you can try building a simple app and exporting it to a repository. Use a recent version of flatpak and flatpak-builer to make sure you can build from Yaml files. This would normally happen on a different machine than the one serving the repository, but for testing we can just do it in a subdirectory:

git clone test-build
cd test-build
flatpak-builder --install-deps-from=flathub --repo=local-repo builddir org.gnome.eog.yml
cd ..

Then we can upload it to the repository by doing (assuming the default secret):

export REPO_TOKEN=$(echo -n "secret" | base64 | cargo run --bin gentoken -- --base64 --secret-file - --name test)
./flat-manager-client push --commit $(./flat-manager-client create stable) test-build/local-repo

This will create a new "build", upload the build to it and then "commit" the build.


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