How to configure runner storage

To prevent the GitHub Action job from exhausting the disk IO of the Juju machine hosting the charm, the charm provides two storage options to be configured as the LXD instance root disk:

• Random access memory as disk
• Storage provided by Juju

This is configured with the runner-storage option. The configuration should be set during deployment and cannot be changed.

Random access memory as disk

The random access memory of the Juju machine is configured as LXD storage and used as the root disk for the LXD instances.

The runner-storage configuration needs to be set to memory during deployment, and the Juju machine constraints should have enough memory for the virtual machine memory and disk. See Managing resource usage.

An example deployment:

juju deploy github-runner --constraints="cores=4 mem=16G root-disk=20G virt-type=virtual-machine" --config token=<TOKEN> --config path=<OWNER/REPO> --config runner-storage=memory --config vm-memory=2GiB --config vm-disk=10GiB

Storage provided by Juju

The Juju storage needs to be mounted during deployment, and the runner-storage configuration should be set to juju-storage during deployment.

An example deployment:

juju deploy github-runner --constraints="cores=4 mem=6G root-disk=30G virt-type=virtual-machine" --config token=<TOKEN> --config path=<OWNER/REPO> --config runner-storage=juju-storage --config vm-memory=2GiB --config vm-memory=10GiB --storage runner=rootfs

The above example uses rootfs, which is using the root disk of the Juju machine. Hence the root-disk size was increase to 30G.