InitLogs overrides the klog default and turns contextual logging off. This
ensures that it is only enabled in Kubernetes commands that explicitly enable
it via a feature gate. A feature gate for it gets defined in
k8s.io/component-base/logs and is then used by Options.ValidateAndApply.
The effect of disabling contextual logging is very limited according to
benchmarks with kube-scheduler. The feature gets added anyway to satisfy the
PRR recommendation that features should be controllable.
The following commands have support for contextual logging:
- kube-apiserver
- kube-controller-manager
- kubelet
- kube-scheduler
- component-base/logs example
Supporting a feature gate check in ValidateAndApply and not in InitLogs is a
simplification: changing InitLogs to accept a FeatureGate would have implied
changing also component-base/cli.Run. This didn't seem worthwhile because
ValidateAndApply already covers the relevant commands.
This commit includes all the changes needed for APIServer. Instead of modifying the existing signatures for the methods which either generate or return stopChannel, we generate a context from the channel and use the generated context to be passed to the controllers which are started in APIServer. This ensures we don't have to touch APIServer dependencies.
Since we removed dockershim we now rely on both flags, which therefore
should not marked experimental any more.
Signed-off-by: Sascha Grunert <sgrunert@redhat.com>
If done too soon, the klog.V() calls are ignored because the log verbosity
isn't set. In Kubernetes 1.22, the verbosity was set, but not the logging
format.
Don't use a custom dialer for the kubelet if is not rotating
certificates, so we can reuse TCP connections because we don't need
a customer dialer.
Kubelet needs to be able to recover from stale http connections.
HTTP2 has a mechanism to detect broken connections by sending periodical pings.
HTTP1 only can have one persistent connection, and it will close all Idle connections
once the Kubelet heartbet fails. However, since there are many edge cases that we can't
control, users can still opt-in to the previous behavior for closing the connections by
setting the environment variable DISABLE_HTTP2.
In various places log messages where emitted as part of validation or even
before it (for example, cli.PrintFlags). Those log messages did not use the
final logging configuration, for example text output instead of JSON or not the
final verbosity. The last point became more obvious after moving the setup of
verbosity into logs.Options.Apply because PrintFlags never printed anything
anymore.
In order to force applications to deal with logging as soon as possible, the
Options.Validate and Options.Apply methods are now private. Applications should
use the new Options.ValidateAndApply directly after parsing.
These three options are the ones from logs.AddFlags which are not deprecated.
Therefore it makes sense to make them available also via the configuration file
support in the one command which currently supports that (kubelet).
Long-term, all commands should use LoggingConfiguration, either with a
configuration file (as in kubelet) or via flags (kube-scheduler,
kube-apiserver, kube-controller-manager).
Short-term, both approaches have to be supported. As the majority of the
commands only use logs.AddFlags, that function by default continues to register
the flags and only leaves that to Options.AddFlags when explicitly requested.
A drive-by bug fix is done for log flushing: the periodic flushing called
klog.Flush and therefore missed explicit flushing of the newer logr
backend. This bug was never present in any release Kubernetes and therefore the
fix is not submitted in a separate PR.
