All code using the result of the generated client-go Informer() (a
cache.SharedIndexInformer) constantly has to do type casts from "any" to the
actual type of the objects managed by the informer.
This is:
- annoying at best
- often done inconsistently (should failed type assertions be logged and if so,
how?)
- a source of bugs (not handling FinalStateUnknown, not handling missing
object, type in event handler not matching the type in the informer)
In contrast, the Lister() result *is* typed. It converts without a type check
in e.g. ResourceIndexer[T].List:
err = cache.ListAllByNamespace(l.indexer, l.namespace, selector, func(m interface{}) {
ret = append(ret, m.(T))
})
This change here does the same wrapping for SharedIndexInformer, Indexer,
index functions and event handler support code. OnDelete is passed
a DeletedObject struct to cover the different scenarios that can occur
when reporting deletion (stale or even nil object!). Extracting key or
name from DeletedObject is guaranteed to never fail because the type-safe
API is restricted to types where the necessary meta data is guaranteed
to be available. This removes another class of tedious error checking.
While not strictly needed, aliases are generated for the generic types because
they are often shorter, easier to type (in particular with auto-complete) and
may help with avoiding an import of k8s.io/client-go/tools/cache.
This is a Go API break because all generated interfaces
change.
Kubernetes-commit: b83b3b39db5eee75af14cdb8d30cfc6899792ec2
Passing a context to StartWithContext enables context-aware reflector
logging. This is the main remaining source of log spam (output to stderr
instead of per-test logger) in controller unit tests.
WaitForCacheSynceWithContext takes advantage of the new cache.WaitFor +
NamedHasSynced functionality to finish "immediately" (= no virtual time
passed) in a synctest bubble. While at it, the return type gets improved so
that a failure is easier to handle.
Kubernetes-commit: 5ff323de791df88880f6e065f5de4b445e5c90ed
For compatibility reasons, the old functions without the ctx parameter still
get generated, now with context.Background instead of context.TODO. In practice
that code won't be used by the client-go reflector code because it prefers
the *WithContext functions, but it cannot be ruled out that some other code
only supports the old fields.
Kubernetes-commit: 8cc74e8a266e1042be1c60adfa3091852036f48a
SharedInformerFactory starts goroutines in Start and those can be stopped by
closing the stop channel. However, there was no API that waits for the
goroutines.
This is a problem for unit testing. A test has to return while the informers
are still running, which may get flagged by tools like
https://github.com/uber-go/goleak or by klog/ktesting when those informers
lead to log output.
While at it, more documentation gets added to address
https://github.com/kubernetes/kubernetes/issues/65036.
Kubernetes-commit: e89d1d47e8365cad31600b17dab662d3c8a359dd
