Here are some instructions for how to set up a flathub build machine.

First you need to get assigned a worker name and a password for that worker. Ask in #flatpak about this.

Then you need an OS with a recent enough flatpak installed. The current intel build machines use CentOS7, which will be used as an example here. Make sure that the clocks and timezones are set up correctly. systemctl enable ntpd should be enough to get this right.

New flatpak builds are available for CentOS here

You also need a somewhat recent version of libappstream-glib that has support for screenshot mirroring. A centos copr for this is here

Then you need to install the basic buildbot and flatpak build dependencies: yum install python-virtualenv gcc flatpak-builder ostree git bzr elfutils libappstream-glib

We also need a newer git: yum install centos-release-scl; yum install rh-git29

Then create a user for the builder ("builder" in the examples below) and allocate a directory with space for the builds (/mnt/builder in the examples).

Now you need to set up a buildbot worker. We use virtualenv for this:

cd /mnt/builder
virtualenv --no-site-packages sandbox
source sandbox/bin/activate
pip install --upgrade pip
pip install buildbot-worker
buildbot-worker create-worker worker hub.flathub.org $BUILDERNAME $BUILDERPASSWORD

After this you will have a worker setup in the worker directory. You can add personal info to the worker/info/host and worker/info/admin files. The worker should now be good enough to start. However, it is prefered to run this as a service. Here is an example systemd service file:

[Unit]
Description=BuildBot worker service
After=network.target

[Service]
User=builder
Group=builder
WorkingDirectory=/mnt/builder/worker
ExecStart=/mnt/builder/sandbox/bin/buildbot-worker start --nodaemon
Environment=PATH=/opt/rh/rh-git29/root/usr/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin
Environment=PERL5LIB=/opt/rh/rh-git29/root/usr/share/perl5/vendor_perl
Environment=LD_LIBRARY_PATH=/opt/rh/httpd24/root/usr/lib64