OK-5121 adding uninstall engine playbook

[GerryMandell]

Summary

Adds uninstall_engine.yml, a new playbook that reverses install_engine.yml. Useful for resetting hosts between test runs, manually decommissioning Orka Engine from a node, and as part of CI cleanup workflows that need to leave the lab in a known-clean state.

Why

install_engine.yml lays down a non-trivial amount of state on the host (LaunchDaemon, app bundle, CLI helper, /opt/orka data + state + logs). Until now there was no playbook-driven way to remove it from the orchestration repo. Operators have had to either:

• SSH in and manually unload the LaunchDaemon, kill processes, and rm -rf the relevant paths
• Run orka-ansible's remove-all.yml, which depends on a working K8s cluster and is overkill when the engine is the only thing installed
• Leave stale engine state across CI runs, which can interfere with the next workflow on shared lab hardware

uninstall_engine.yml makes the install/uninstall pair symmetric and removable on its own.

What it removes

• Unloads the com.macstadium.orka-engine.server.managed LaunchDaemon
• Removes the LaunchDaemon plist at /Library/LaunchDaemons/com.macstadium.orka-engine.server.managed.plist
• Kills any running com.macstadium.orka-engine.runvz processes
• Removes the engine data and state directories at /opt/orka (data, logs, VM state)
• Removes the engine app at /usr/local/libexec/orka-engine.app
• Removes the orka-engine CLI helper at /usr/local/bin/orka-engine

Paths match install_engine defaults exactly so this is a true inverse of the installer.

Optional variables

• uninstall_engine_data (default true) — remove /opt/orka. Set to false to preserve VM state across reinstalls (useful for upgrades where you want to keep cached images and VM data).

README updates included

• New "Uninstall Engine" section paired with the existing "Install Engine" section
• Updated project-structure list to include the new playbook
• Corrected an erroneous reference to install_engine.yml playbook.

Test plan

• Run install_engine.yml on a clean host — confirm engine installs, LaunchDaemon loads, orka-engine CLI works
• Run uninstall_engine.yml on the same host — confirm:
  • LaunchDaemon is unloaded (launchctl list | grep orka-engine returns nothing)
  • Plist is gone (/Library/LaunchDaemons/com.macstadium.orka-engine.server.managed.plist)
  • No orka-engine processes running (pgrep orka-engine)
  • /opt/orka, /usr/local/libexec/orka-engine.app, /usr/local/bin/orka-engine are gone
• Run install_engine.yml again on the now-cleaned host — confirm clean reinstall succeeds (idempotency check)
• Run uninstall_engine.yml -e "uninstall_engine_data=false" — confirm engine binaries are removed but /opt/orka remains

[relwell]

This ansible lint warning is probably worth reviewing

[ybenchouaf]

Thanks Gerry! Good addition to have symmetry with install_engine.yml. LGTM.

Small note: the README calls it install-engine.yml instead of install_engine.yml. I don't know if that's something we want to fix in this PR, but figured I'd flag it.

[spikeburton]

Note - launchctl unload is deprecated (see man launchctl). We should opt for launchctl bootout - this is what we use in the monorepo and is the preferred modern way of unloading the service