Comparison
Desired statevsObserved state
Desired state
you said three replicas, and every time someone deletes one a fourth appears without anybody being asked.
The recorded intent a controller works towards, held in the control plane rather than in anyone's head. Because it is authoritative, manual changes to the running system are not changes at all — they are deviations that will be undone, sometimes within seconds. This is the single most common shock for someone arriving from virtual machines, where what you did by hand stayed done.
Full entry →Observed state
the spec says three and the status says one, and the gap between those two numbers is the entire incident.
What the system actually reports it has, as opposed to what was asked for. Every orchestrated object carries both, and reading the two side by side is the fastest diagnostic there is: matching means healthy, persistently diverging means a controller is trying and failing and its events will say why. Dashboards that only show desired state look green through an entire outage.
Full entry →