Found by a three-machine install on fresh VMs. The second standby's run
asked for the floating address's interface with `ip route get <vip>`.
The machine already held the address, so that answered lo, and keepalived
would not start. The interface now comes from the route to the address's
network. Every cluster's VRRP router id was 51, so the PoC's two control
planes and the new three on one LAN each logged the other's adverts as an
invalid password; the id now comes from the address.
The Caddyfile, deploy/ha and install.md send clients to the control plane
whose /leader is 200, not /ready: /ready is 503 on a leader with no model
yet and would take the portal away with it. Setup no longer hides a key
file's path as if it were a password, and the starter's text no longer
says it runs elsewhere when this machine is a node.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
The last piece of HA, and it is a deployment pattern rather than code: llmgw
picks one leader and agents follow it, but client traffic arrives in front of
both and llmgw is not in front of anything.
Writing the pattern found a bug in the pattern. The first draft said to
health-check `/health` and claimed a standby still routes to replicas the
leader placed, so sending it traffic was fine. It does not. A standby's
reconciler places nothing and it holds no agent streams to adopt from, so it
publishes an empty endpoint list — a load balancer following that advice would
have sent half the traffic to something that answers every request with 503.
So there is now a `/ready` that means "this process has somewhere to send a
request": 503 on a standby, 503 on a leader whose replicas have all failed,
200 when there is something to serve. `/health` keeps meaning the process is
up, which is a different and less useful question. Both are open, because a
load balancer has no key.
There is a gap during failover where neither passes — three seconds when the
leader stops cleanly, up to the lease TTL when it does not — and the document
says so rather than implying otherwise. Traffic cannot go to a control plane
that has nothing to route to.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
