We call the primary management unit handled by ha-manager
a
resource. A resource (also called “service”) is uniquely
identified by a service ID (SID), which consists of the resource type
and a type specific ID, for example vm:100
. That example would be a
resource of type vm
(virtual machine) with the ID 100.
For now we have two important resources types - virtual machines and
containers. One basic idea here is that we can bundle related software
into such a VM or container, so there is no need to compose one big
service from other services, as was done with rgmanager
. In
general, a HA managed resource should not depend on other resources.