The code for the scheduler is located in wraxl/*.py files. It uses standard python development tooling and pex to create a standalone bundle dist/wraxl_scheduler.

By default, it reads config from /etc/wraxl_scheduler.yaml. This config file contains the current releases 5,6,7,8 and master. Each release has a weight, name, file with configurations and a list of valid host containers for that release.

When an offer is received, the scheduler chooses a release using a weighted random selection algorithm, then chooses host and configuration as random.

Using existing Python RQ installation on lpd-web, I created three queues: wraxl_high, wraxl_low and wraxl_world. The build scheduler monitors these queues. If a high priority resource is offered and there is a task on any of these queues, the task is moved to temporary queue and a container running the RQ worker is started. The worker will then execute the task in burst mode and exit when the task execution is complete.

This setup is used to rebuild native sstate daily. It is used by OVP project to build daily images for LAVA tests. It is also used by wrgit devbuild.

Use make to build the pex bundle. Use make image to build the mesos-scheduler docker image.

Use the start_wraxl_test_cluster.sh to start the full wraxl stack on a single machine using docker-compose. For more info please read local_test_setup.md.