wire up feature_gate.go with metrics via AddMetrics method
Change-Id: I9b4f6b04c0f4eb9bcb198b16284393d21c774ad8
wire in metrics to kubernetes components
Change-Id: I6d4ef8b26f149f62b03f32d1658f04f3056fe4dc
rename metric since we're using the value to determine if enabled is true or false
Change-Id: I13a6b6df90a5ffb4b9c5b34fa187562413bea029
Update staging/src/k8s.io/component-base/featuregate/feature_gate.go
Co-authored-by: Jordan Liggitt <jordan@liggitt.net>
Making the LoggingConfiguration part of the versioned component-base/config API
had the theoretic advantage that components could have offered different
configuration APIs with experimental features limited to alpha versions (for
example, sanitization offered only in a v1alpha1.KubeletConfiguration). Some
components could have decided to only use stable logging options.
In practice, this wasn't done. Furthermore, we don't want different components
to make different choices regarding which logging features they offer to
users. It should always be the same everywhere, for the sake of consistency.
This can be achieved with a saner Go API by dropping the distinction between
internal and external LoggingConfiguration types. Different stability levels of
indidividual fields have to be covered by documentation (done) and potentially
feature gates (not currently done).
Advantages:
- everything related to logging is under component-base/logs;
previously this was scattered across different packages and
different files under "logs" (why some code was in logs/config.go
vs. logs/options.go vs. logs/logs.go always confused me again
and again when coming back to the code):
- long-term config and command line API are clearly separated
into the "api" package underneath that
- logs/logs.go itself only deals with legacy global flags and
logging configuration
- removal of separate Go APIs like logs.BindLoggingFlags and
logs.Options
- LogRegistry becomes an implementation detail, with less code
and less exported functionality (only registration needs to
be exported, querying is internal)
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 PR removes Serve function and uses all required places
ServeWithListenerStopped which takes place new Serve function.
This function returns ListenerStopped channel can be used to drain
requests before shutting down the server.
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.
The recommendation from #sig-cli was to print usage, then the error. Extra care
is taken to only print the usage instruction when the error really was about
flag parsing.
Taking kube-scheduler as example:
$ _output/bin/kube-scheduler
I0929 09:42:42.289039 149029 serving.go:348] Generated self-signed cert in-memory
...
W0929 09:42:42.489255 149029 client_config.go:620] error creating inClusterConfig, falling back to default config: unable to load in-cluster configuration, KUBERNETES_SERVICE_HOST and KUBERNETES_SERVICE_PORT must be defined
E0929 09:42:42.489366 149029 run.go:98] "command failed" err="invalid configuration: no configuration has been provided, try setting KUBERNETES_MASTER environment variable"
$ _output/bin/kube-scheduler --xxx
Usage:
kube-scheduler [flags]
...
--vmodule moduleSpec
comma-separated list of pattern=N settings for file-filtered logging
Error: unknown flag: --xxx
The kubectl behavior doesn't change:
$ _output/bin/kubectl get nodes
Unable to connect to the server: dial tcp: lookup xxxx: No address associated with hostname
$ _output/bin/kubectl --xxx
Error: unknown flag: --xxx
See 'kubectl --help' for usage.
All Kubernetes commands should show flags with hyphens in their help text even
when the flag originally was defined with underscore. Converting a command to
this style is not breaking its command line API because the old-style parameter
with underscore is accepted as alias.
The easiest solution to achieve this is to set normalization shortly before
running the command in the new central cli.Run or the few places where that
function isn't used yet.
There may be some texts which depends on normalization at flag definition time,
like the --logging-format usage warning. Those get generated assuming that
hyphens will be used.
It wasn't documented that InitLogs already uses the log flush frequency, so
some commands have called it before parsing (for example, kubectl in the
original code for logs.go). The flag never had an effect in such commands.
Fixing this turned into a major refactoring of how commands set up flags and
run their Cobra command:
- component-base/logs: implicitely registering flags during package init is an
anti-pattern that makes it impossible to use the package in commands which
want full control over their command line. Logging flags must be added
explicitly now, something that the new cli.Run does automatically.
- component-base/logs: AddFlags would have crashed in kubectl-convert if it
had been called because it relied on the global pflag.CommandLine. This
has been fixed and kubectl-convert now has the same --log-flush-frequency
flag as other commands.
- component-base/logs/testinit: an exception are tests where flag.CommandLine has
to be used. This new package can be imported to add flags to that
once per test program.
- Normalization of the klog command line flags was inconsistent. Some commands
unintentionally didn't normalize to the recommended format with hyphens. This
gets fixed for sample programs, but not for production programs because
it would be a breaking change.
This refactoring has the following user-visible effects:
- The validation error for `go run ./cmd/kube-apiserver --logging-format=json
--add-dir-header` now references `add-dir-header` instead of `add_dir_header`.
- `staging/src/k8s.io/cloud-provider/sample` uses flags with hyphen instead of
underscore.
- `--log-flush-frequency` is not listed anymore in the --logging-format flag's
`non-default formats don't honor these flags` usage text because it will also
work for non-default formats once it is needed.
- `cmd/kubelet`: the description of `--logging-format` uses hyphens instead of
underscores for the flags, which now matches what the command is using.
- `staging/src/k8s.io/component-base/logs/example/cmd`: added logging flags.
- `apiextensions-apiserver` no longer prints a useless stack trace for `main`
when command line parsing raises an error.
