the new field exists primarily to avoid returning a 404 response when a resource actually exists but we haven't installed the path to a handler.
it is exposed for easier composition of the individual servers.
the primary users of this field are the WithMuxCompleteProtection filter and the NotFoundHandler.
It puts the muxCompleteProtectionKey in the context if a request has been made before muxCompleteSignal has been ready.
Putting the key protect us from returning a 404 response instead of a 503.
It is especially important for controllers like GC and NS since they act on 404s.
The presence of the key is checked in the NotFoundHandler (staging/src/k8s.io/apiserver/pkg/util/notfoundhandler/not_found_handler.go)
The race may happen when a request reaches the NotFoundHandler because not all paths have been registered in the mux
but when the registered checks are examined in the handler they indicate that the paths have been actually installed.
In that case, the presence of the key will make the handler return 503 instead of 404.
The new handler is meant to be executed at the end of the delegation chain.
It simply checks if the request have been made before the server has installed all known HTTP paths.
In that case it returns a 503 response otherwise it returns a 404.
We don't want to add additional checks to the readyz path as it might prevent fixing bricked clusters.
This specific handler is meant to "protect" requests that arrive before the paths and handlers are fully initialized.
This implements the replacement of klog output to different files per level
with optionally splitting JSON output into two streams: one for info messages
on stdout, one for error messages on stderr. The info messages can get buffered
to increase performance. Because stdout and stderr might be merged by the
consumer, the info stream gets flushed before writing an error, to ensure that
the order of messages is preserved.
This also ensures that the following code pattern doesn't leak info messages:
klog.ErrorS(err, ...)
os.Exit(1)
Commands explicitly have to flush before exiting via logs.FlushLogs. Most
already do. But buffered info messages can still get lost during an unexpected
program termination, therefore buffering is off by default.
The new options get added to the v1alpha1 LoggingConfiguration with new command
line flags. Because it is an alpha field, changing it inside the v1beta kubelet
config should be okay as long as the fields are clearly marked as alpha.
The Quantity type itself cannot be used because the Set method has the wrong
signature. Embedding Quantity inside a new QuantityValue type makes it possible
to inherit most of the methods while overriding the Set method.
