Central and each site are SEPARATE Akka clusters, so central cannot act on a
site's membership -- it asks. New TriggerSiteFailover/SiteFailoverAck contract
travels the existing ClusterClient command/control channel (mirroring the
RetryParkedOperation relay); the site's own SiteCommunicationActor performs the
graceful Leave and acks the outcome.
- ClusterFailoverCoordinator moved out of Host into Communication/ClusterState,
beside ActiveNodeEvaluator. Both paths now share ONE oldest-Up implementation;
SiteCommunicationActor cannot reference Host, and the two definitions must not
drift or the node asked to leave stops being the singleton host.
- Site scope is the SITE-SPECIFIC role (site-{SiteId}), not the base Site role --
site singletons are placed on the former, so the base role would move the wrong
node. Pinned by a unit test asserting the role string and by a real-cluster test.
- Site-side guards: refuses a command addressed to another site (a misroute must
never fail over a site the operator did not select), refuses when there is no
peer, and reports a fault as an ack rather than throwing into supervision --
a restart there would drop central's Ask into a bare timeout and lose the reason.
- Ack is sent before the Leave takes effect so it still reaches central.
- UI: the same control now serves both scopes via a SiteId parameter. The site
confirmation deliberately does NOT claim the admin's page will disconnect --
it won't, and crying wolf there devalues the central warning that is real. A
site refusal and an unreachable site surface distinctly.
- Rolling upgrade: a site on an older binary has no handler, so the message
dead-letters and the Ask times out, reported as "site did not respond". That
is the honest outcome; documented on the contract.
Fallout fixed: HealthPageTests now renders the page inside
CascadingAuthenticationState with the real policy set and IAuthorizationService,
because the cards embed an AuthorizeView. That mirrors production, where the
layout supplies the cascading value.
Joseph Doherty