Fighting Game · Guides & deep dives

V2 Build Farm Provisioning

The initial pools cover Linux Unreal/Rust work, Linux ARM64 server builds, Windows Unreal builds, Mac editor builds, and console-cert jobs.

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V2/ue/Build/Farm/v2-build-farm-provisioning.json is the source of truth for CI-triggered build-agent autoscaling. It provisions agents when pull requests, main pushes, workflow dispatches, nightly jobs, or weekly jobs queue work, then scales each pool back to zero after 30 idle minutes with scaleToZeroOnIdle.

Pools#

The initial pools cover Linux Unreal/Rust work, Linux ARM64 server builds, Windows Unreal builds, Mac editor builds, and console-cert jobs. Every pool has minIdleAgents: 0, a bounded max agent count, and a queue-depth trigger so the provisioner can add capacity without leaving expensive idle machines running.

Agent Lifecycle#

Linux agents use V2/ue/Build/Farm/linux-agent-cloud-init.yaml. The bootstrap creates the v2build user, installs Git, Python, jq, bubblewrap, and build tools, registers the Horde agent with a Vault-rendered token, and starts the local sccache client. Workspaces are wiped before and after jobs while shared DDC, UBA, and sccache caches remain outside the ephemeral workspace.

Gates#

The Horde job publishes three required build-farm provisioning gates:

  • build-farm-provision-latency keeps CI-triggered agent startup at or below 600 seconds.
  • build-farm-idle-scale-zero proves idle pools returned to zero agents.
  • build-farm-orphan-cleanup fails if any stale provisioned agent remains.

Operators should publish $(ArchiveRoot)/BuildFarm/provisioning-health.json from each provisioning sweep with active, idle, orphaned, queue-depth, and latency metrics.