Currently, there are some unit tests that are failing on Windows due to
various reasons:
- config options not supported on Windows.
- files not closed, which means that they cannot be removed / renamed.
- paths not properly joined (filepath.Join should be used).
- time.Now() is not as precise on Windows, which means that 2
consecutive calls may return the same timestamp.
- different error messages on Windows.
- files have \r\n line endings on Windows.
- /tmp directory being used, which might not exist on Windows. Instead,
the OS-specific Temp directory should be used.
- the default value for Kubelet's EvictionHard field was containing
OS-specific fields. This is now moved, the field is now set during
Kubelet's initialization, after the config file is read.
cpu.cfs_period_us is measured in microseconds in the kernel but
provided in time.Duration by the user, that change clarifies the code
to make this evident to the reader.
Also, the minimum value for that feature is 1ms and not 1μs, and this
change alters the validation to reject values smaller than 1ms.
cpu.cfs_period_us is 100μs by default despite having an "ms" unit
for some unfortunate reason. Documentation:
https://www.kernel.org/doc/html/latest/scheduler/sched-bwc.html#management
The desired effect of that change is to match
k8s default `CPUCFSQuotaPeriod` value (100ms before that change)
with one used in k8s without the `CustomCPUCFSQuotaPeriod` flag enabled
and Linux CFS (100us, 1000x smaller than 100ms).
cpu.cfs_period_us is 100μs by default despite having an "ms" unit
for some unfortunate reason. Documentation:
https://www.kernel.org/doc/html/latest/scheduler/sched-bwc.html#management
The desired effect of that change is to match
k8s default `CPUCFSQuotaPeriod` value (100ms before that change)
with one used in k8s without the `CustomCPUCFSQuotaPeriod` flag enabled
and Linux CFS (100us, 1000x smaller than 100ms).
cpu.cfs_period_us is 100μs by default despite having an "ms" unit
for some unfortunate reason. Documentation:
https://www.kernel.org/doc/html/latest/scheduler/sched-bwc.html#management
The desired effect of that change is more clarity on the default value
so users would be aware that the 10ms custom value would be
not 0.1x of the default, but 100x of it.
It is useful to have the ability to control whether alpha or beta features are
enabled. We can group features under LoggingAlphaOptions and LoggingBetaOptions
because the configuration is designed so that each feature individually must be
enabled via its own option.
Currently, the JSON format itself is beta (graduated in 1.23) but additional
options for it were only added in 1.23 and thus are still alpha:
$ go run ./staging/src/k8s.io/component-base/logs/example/cmd/logger.go --logging-format=json --log-json-split-stream --log-json-info-buffer-size 1M --feature-gates LoggingBetaOptions=false
[format: Forbidden: Log format json is BETA and disabled, see LoggingBetaOptions feature, options.json.splitStream: Forbidden: Feature LoggingAlphaOptions is disabled, options.json.infoBufferSize: Forbidden: Feature LoggingAlphaOptions is disabled]
$ go run ./staging/src/k8s.io/component-base/logs/example/cmd/logger.go --logging-format=json --log-json-split-stream --log-json-info-buffer-size 1M
[options.json.splitStream: Forbidden: Feature LoggingAlphaOptions is disabled, options.json.infoBufferSize: Forbidden: Feature LoggingAlphaOptions is disabled]
This is the same approach that was taken for CPUManagerPolicyAlphaOptions and
CPUManagerPolicyBetaOptions.
In order to test this without modifying the global feature gate in a test file,
ValidateKubeletConfiguration must take a feature gate as argument.
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)
- Change the feature gate from alpha to beta and enable it by default
- Update a few of the unit tests due to feature gate being enabled by
default
- Small refactor in `nodeshutdown_manager` which adds `featureEnabled`
function (which checks that feature gate and that
`kubeletConfig.ShutdownGracePeriod > 0`).
- Use `featureEnabled()` to exit early from shutdown manager in the case
that the feature is disabled
- Update kubelet config defaulting to be explicit that
`ShutdownGracePeriod` and `ShutdownGracePeriodCriticalPods` default to
zero and update the godoc comments.
- Update defaults and add featureGate tag in api config godoc.
With this feature now in beta and the feature gate enabled by default,
to enable graceful shutdown all that will be required is to configure
`ShutdownGracePeriod` and `ShutdownGracePeriodCriticalPods` in the
kubelet config. If not configured, they will be defaulted to zero, and
graceful shutdown will effectively be disabled.
We will have two layers of the validation.
- the first part of the validation logic will be implemented under the
`ValidateKubeletConfiguration` method
- the second one that requires knowledge about machine topology and
node allocatable resources will be implemented under the memory manager.
Signed-off-by: Artyom Lukianov <alukiano@redhat.com>
Implements KEP 2000, Graceful Node Shutdown:
https://github.com/kubernetes/enhancements/tree/master/keps/sig-node/2000-graceful-node-shutdown
* Add new FeatureGate `GracefulNodeShutdown` to control
enabling/disabling the feature
* Add two new KubeletConfiguration options
* `ShutdownGracePeriod` and `ShutdownGracePeriodCriticalPods`
* Add new package, `nodeshutdown` that implements the Node shutdown
manager
* The node shutdown manager uses the systemd inhibit package, to
create an system inhibitor, monitor for node shutdown events, and
gracefully terminate pods upon a node shutdown.
