If a hinted Node is no longer in the cluster snapshot (e.g. it was
a fake upcoming Node and the real one appeared).
This was introduced in the recent PredicateChecker->PredicateSnapshot
refactor. Previously, PredicateChecker.CheckPredicates() would return
an error if the hinted Node was gone, and HintingSimulator treated
this error the same as failing predicates - it would move on to the
non-hinting logic. After the refactor, HintingSimulator explicitly
errors out if it can't retrieve the hinted Node from the snapshot,
so the behavior changed.
I checked other CheckPredicates()/SchedulePod() callsites, and this is
the only one when ignoring the missing Node makes sense. For the others,
the Node is added to the snapshot just before the call, so it being
missing should cause an error.
This decouples PredicateChecker from the Framework initialization logic,
and allows creating multiple PredicateChecker instances while only
initializing the framework once.
This commit also fixes how CA integrates with Framework metrics. Instead
of Registering them they're only Initialized so that CA doesn't expose
scheduler metrics. And the initialization is moved from multiple
different places to the Handle constructor.
The new wrapper types should behave like the direct schedulerframework
types for most purposes, so most of the migration is just changing
the imported package.
Constructors look a bit different, so they have to be adapted -
mostly in test code. Accesses to the Pods field have to be changed
to a method call.
After this, the schedulerframework types are only used in the new
wrappers, and in the parts of simulator/ that directly interact with
the scheduler framework. The rest of CA codebase operates on the new
wrapper types.
Kuba Tużnik
Bartłomiej Wróblewski
Daniel Kłobuszewski