Automatic merge from submit-queue (batch tested with PRs 51956, 50708)
Move autoscaling/v2 from alpha1 to beta1
This graduates autoscaling/v2alpha1 to autoscaling/v2beta1. The move is more-or-less just a straightforward rename.
Part of kubernetes/features#117
```release-note
v2 of the autoscaling API group, including improvements to the HorizontalPodAutoscaler, has moved from alpha1 to beta1.
```
Introduce feature gate for expanding PVs
Add a field to SC
Add new Conditions and feature tag pvc update
Add tests for size update via feature gate
register the resize admission plugin
Update golint failures
Automatic merge from submit-queue
Enable batch/v1beta1.CronJobs by default
This PR re-applies the cronjobs->beta back (https://github.com/kubernetes/kubernetes/pull/51720) with the fix from @shyamjvs.
Fixes#51692
@apelisse @dchen1107 @smarterclayton ptal
@janetkuo @erictune fyi
Automatic merge from submit-queue (batch tested with PRs 51805, 51725, 50925, 51474, 51638)
Limit events accepted by API Server
**What this PR does / why we need it**:
This PR adds the ability to limit events processed by an API server. Limits can be set globally on a server, per-namespace, per-user, and per-source+object. This is needed to prevent badly-configured or misbehaving players from making a cluster unstable.
Please see https://github.com/kubernetes/community/pull/945.
**Release Note:**
```release-note
Adds a new alpha EventRateLimit admission control that is used to limit the number of event queries that are accepted by the API Server.
```
Remove APIService OpenAPI spec when it is deleted
Add eTag support and returning httpStatus to OpenAPI spec downloader
Update aggregated OpenAPI spec periodically
Use delegate chain
Refactor OpenAPI aggregator to have separate controller and aggregation function
Enable OpenAPI spec for extensions api server
Do not filter paths. higher priority specs wins the conflicting paths
Move OpenAPI aggregation controller to pkg/controller/openapi
The EventRateLimit plug-in limits the number of events that the API Server
will accept in a given time period. It allows for server-wide, per-namespace,
per-user,and per-source+object rate limiting.
Automatic merge from submit-queue (batch tested with PRs 50775, 51397, 51168, 51465, 51536)
Enable batch/v1beta1.CronJobs by default
This PR moves to CronJobs beta entirely, enabling `batch/v1beta1` by default.
Related issue: #41039
@erictune @janetkuo ptal
```release-note
Promote CronJobs to batch/v1beta1.
```
Automatic merge from submit-queue
Add Google cloud KMS service for envelope encryption transformer
This adds the required pieces which will allow addition of KMS based encryption providers (envelope transformer).
For now, we will be implementing it using Google Cloud KMS, but the code should make it easy to add support for any other such provider which can expose Decrypt and Encrypt calls.
Writing tests for Google Cloud KMS Service may cause a significant overhead to the testing framework. It has been tested locally and on GKE though.
Upcoming after this PR:
* Complete implementation of the envelope transformer, which uses LRU cache to maintain decrypted DEKs in memory.
* Track key version to assist in data re-encryption after a KEK rotation.
Development branch containing the changes described above: https://github.com/sakshamsharma/kubernetes/pull/4
Envelope transformer used by this PR was merged in #49350
Concerns #48522
Planned configuration:
```
kind: EncryptionConfig
apiVersion: v1
resources:
- resources:
- secrets
providers:
- kms:
cachesize: 100
configfile: gcp-cloudkms.conf
name: gcp-cloudkms
- identity: {}
```
gcp-cloudkms.conf:
```
[GoogleCloudKMS]
kms-location: global
kms-keyring: google-container-engine
kms-cryptokey: example-key
```
Automatic merge from submit-queue (batch tested with PRs 51471, 50561, 50435, 51473, 51436)
Feature gate initializers field
The metadata.initializers field should be feature gated and disabled by default while in alpha, especially since enforcement of initializer permission that keeps users from submitting objects with their own initializers specified is done via an admission plugin most clusters do not enable yet.
Not gating the field and tests caused tests added in https://github.com/kubernetes/kubernetes/issues/51429 to fail on clusters that don't enable the admission plugin.
This PR:
* adds an `Initializers` feature gate, auto-enables the feature gate if the admission plugin is enabled
* clears the `metadata.initializers` field of objects on create/update if the feature gate is not set
* marks the e2e tests as feature-dependent (will follow up with PR to test-infra to enable the feature and opt in for GCE e2e tests)
```release-note
Use of the alpha initializers feature now requires enabling the `Initializers` feature gate. This feature gate is auto-enabled if the `Initialzers` admission plugin is enabled.
```
Automatic merge from submit-queue (batch tested with PRs 51134, 51122, 50562, 50971, 51327)
set --audit-log-format default to json
Updates: https://github.com/kubernetes/kubernetes/issues/48561
**Release note**:
```
set --audit-log-format default to json for kube-apiserver
```
Automatic merge from submit-queue (batch tested with PRs 50213, 50707, 49502, 51230, 50848)
Expand the test to include other flags as well
**What this PR does / why we need it**:
Expand the test to include other flags as well
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #
**Special notes for your reviewer**:
**Release note**:
```release-note
```
`NONE`
The current registration of admission plug-ins happen too late so the
command line help is not yielding correct/useful information to users.
This is already causing confusion as mentioned in some issues.
This patch fixes it by moving plugins.go down to options package because
"plugins" in this context are themselves options for users. Registration
of plugins is not an expensive operation and it is already done in most
execution paths.
In future, we may want to revisit these plugins and migrate them to the
shared apiserver repo when appropriate.
Automatic merge from submit-queue
Add Priority admission controller
**What this PR does / why we need it**: Add Priority admission controller. This admission controller checks creation and update of PriorityClasses. It also resolves a PriorityClass name of a pod to its integer value.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #
**Special notes for your reviewer**:
**Release note**:
```release-note
Add Priority admission controller for monitoring and resolving PriorityClasses.
```
ref/ #47604
ref/ #48646
Automatic merge from submit-queue (batch tested with PRs 49488, 50407, 46105, 50456, 50258)
Enable caching successful token authentication
Resolves#50472
To support revocation of service account tokens, an etcd lookup of the token and service account is done by the token authenticator. Controllers that make dozens or hundreds of API calls per second (like the endpoints controller) cause this lookup to be done very frequently on the same objects.
This PR:
* Implements a cached token authenticator that conforms to the authenticator.Token interface
* Implements a union token authenticator (same approach as the union request authenticator, conforming to the authenticator.Token interface)
* Cleans up the auth chain construction to group all token authenticators (means we only do bearer and websocket header parsing once)
* Adds a 10-second TTL cache to successful token authentication
```release-note
API server authentication now caches successful bearer token authentication results for a few seconds.
```
Automatic merge from submit-queue (batch tested with PRs 49989, 49806, 49649, 49412, 49512)
This adds an etcd health check endpoint to kube-apiserver
addressing https://github.com/kubernetes/kubernetes/issues/48215.
**What this PR does / why we need it**:
This ensures kube-apiserver `/healthz` endpoint fails whenever connectivity cannot be established to etcd, also ensures the etcd preflight checks works with unix sockets
**Which issue this PR fixes**: fixes#48215
**Special notes for your reviewer**:
This PR does not use the etcd client directly as the client object is wrapped behind the storage interface and not exposed directly for use, so I decided to reuse what's being done in the preflight. So this will only check fail for connectivity and not etcd auth related problems. I did not write tests for the endpoint because I couldn't find examples that I could follow for writing tests for healthz related endpoints, I'll be willing to write those tests if someone can point me at a relevant one.
**Release note**:
```release-note
Add etcd connectivity endpoint to healthz
```
@deads2k please help review, thanks!
Automatic merge from submit-queue (batch tested with PRs 49992, 48861, 49267, 49356, 49886)
Reintegrate aggregation support for OpenAPI
Reintegrating changes of #46734
Changes summary:
- Extracted all OpenAPI specs to new repo `kube-openapi`
- Make OpenAPI spec aggregator to copy and rename any non-requal model (even with documentation change only).
- Load specs when adding APIServices and retry on failure until successful spec retrieval or a 404.
- Assumes all Specs except aggregator's Spec are static
- A re-register of any APIService will result in updating the spec for that service (Suggestion for TPR: they should be registered to aggregator API Server, Open for discussion if any more changes needed for another PR.)
fixes#48548
Automatic merge from submit-queue (batch tested with PRs 49871, 49422, 49092, 49858, 48999)
adding kube-apiserver starting option tests
**What this PR does / why we need it**:
There is only one test for `--enable-swagger-ui` option in `cmd/kube-apiserver/app/options/options_test.go`, I have expanded this test with more kube-apiserver starting options.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #
**Special notes for your reviewer**:
**Release note**:
`NONE`
Automatic merge from submit-queue (batch tested with PRs 44129, 48030, 48906)
Add default=false to usage of kube-apiserver allow-privileged flag
**What this PR does / why we need it**:
Users will be clear about default value of `allow-privileged` flag.
Automatic merge from submit-queue (batch tested with PRs 48480, 48353)
remove tpr api access
xref https://github.com/kubernetes/kubernetes/issues/48152
TPR tentacles go pretty deep. This gets us started by removing API access and we'll move down from there.
@kubernetes/sig-api-machinery-misc
@ironcladlou this should free up the GC implementation since TPRs will no longer be present and failing.
```release-note
Removing TPR api access per https://github.com/kubernetes/kubernetes/issues/48152
```
Automatic merge from submit-queue (batch tested with PRs 48012, 47443, 47702, 47178)
incluster config will be used when creating external shared informers.
**What this PR does / why we need it**:
Previously the loopback configuration was used to talk to the server.
As a consequence a custom API server was unable to talk to the root API server.
This PR changes the above by using incluster configuration to create shared informers.
**Release note**:
```release-note
NONE
```
Automatic merge from submit-queue (batch tested with PRs 47878, 47503, 47857)
restore working aggregator and avoid duplicate informers
Fixes https://github.com/kubernetes/kubernetes/issues/47866
This runs the informer all the way through and makes sure its started.
@lavalamp ptal
@kubernetes/sig-api-machinery-bugs
Automatic merge from submit-queue
Separate serviceaccount and secret storage config
Fixes#47815, and is required in order to enable the secret encryption feature with a recommended configuration
This passes distinct storage options for serviceaccounts and secrets, since secrets can now have an encrypting transformer associated with them
Automatic merge from submit-queue (batch tested with PRs 47726, 47693, 46909, 46812)
Plumb service resolver into webhook AC
This is the last piece of plumbing needed for https://github.com/kubernetes/features/issues/209
Automatic merge from submit-queue
bazel: stamp multiple packages by using x_defs instead of linkstamp in go_binary rules
**What this PR does / why we need it**: Fixes regression introduced sometime in the last few months that prevented bazel-built clusters from identifying version properly.
It does so by updating the bazelbuild/rules_go and kubernetes/repo-infra dependencies to support using stamp values in `go_binary` `x_defs`, and then changing our `go_binary` rules to use `x_defs` instead of `linkstamp`.
This whole charade is necessary because we need to stamp version information in multiple packages.
This pretty much only affects the bazel build, so it should be low risk.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes#45298
**Special notes for your reviewer**: depends on https://github.com/kubernetes/repo-infra/pull/18; should not be merged before it.
**Release note**:
```release-note
NONE
```
/assign @spxtr @mikedanese
Automatic merge from submit-queue (batch tested with PRs 46718, 46828, 46988)
Simply changed the names of packages of some admission plugins.
**What this PR does / why we need it**:
This PR simply changes the names of packages of some admission plugins so that they are not in conflict with admission pkg.
**Release note**:
```release-note
NONE
```
Automatic merge from submit-queue (batch tested with PRs 46550, 46663, 46816, 46820, 46460)
Add configuration for encryption providers
## Additions
Allows providing a configuration file (using flag `--experimental-encryption-provider-config`) to use the existing AEAD transformer (with multiple keys) by composing mutable transformer, prefix transformer (for parsing providerId), another prefix transformer (for parsing keyId), and AES-GCM transformers (one for each key). Multiple providers can be configured using the configuration file.
Example configuration:
```
kind: EncryptionConfig
apiVersion: v1
resources:
- resources:
- namespaces
providers:
- aes:
keys:
- name: key1
secret: c2vjcmv0iglzihnly3vyzq==
- name: key2
secret: dghpcybpcybwyxnzd29yza==
- identity: {}
```
Need for configuration discussed in:
#41939
[Encryption](3418b4e4c6/contributors/design-proposals/encryption.md)
**Pathway of a read/write request**:
1. MutableTransformer
2. PrefixTransformer reads the provider-id, and passes the request further if that matches.
3. PrefixTransformer reads the key-id, and passes the request further if that matches.
4. GCMTransformer tries decrypting and authenticating the cipher text in case of reads. Similarly for writes.
## Caveats
1. To keep the command line parameter parsing independent of the individual transformer's configuration, we need to convert the configuration to an `interface{}` and manually parse it in the transformer. Suggestions on better ways to do this are welcome.
2. Flags `--encryption-provider` and `--encrypt-resource` (both mentioned in [this document](3418b4e4c6/contributors/design-proposals/encryption.md) ) are not supported in this because they do not allow more than one provider, and the current format for the configuration file possibly supersedes their functionality.
3. Currently, it can be tested by adding `--experimental-encryption-provider-config=config.yml` to `hack/local-up-cluster.sh` on line 511, and placing the above configuration in `config.yml` in the root project directory.
Previous discussion on these changes:
https://github.com/sakshamsharma/kubernetes/pull/1
@jcbsmpsn @destijl @smarterclayton
## TODO
1. Investigate if we need to store keys on disk (per [encryption.md](3418b4e4c6/contributors/design-proposals/encryption.md (option-1-simple-list-of-keys-on-disk)))
2. Look at [alpha flag conventions](https://github.com/kubernetes/kubernetes/blob/master/pkg/features/kube_features.go)
3. Need to reserve `k8s:enc` prefix formally for encrypted data. Else find a better way to detect transformed data.
Handle failure cases on startup gracefully to avoid causing cascading
errors and poor initialization in other components. Initial errors from
config load cause the initializer to pause and hold requests. Return
typed errors to better communicate failures to clients.
Add code to handle two specific cases - admin wants to bypass
initialization defaulting, and mirror pods (which want to bypass
initialization because the kubelet owns their lifecycle).
Automatic merge from submit-queue (batch tested with PRs 46681, 46786, 46264, 46680, 46805)
Enable Dialer on the Aggregator
Centralize the creation of the dialer during startup.
Have the dialer then passed in to both APIServer and Aggregator.
Aggregator the uses the dialer as its Transport base.
**What this PR does / why we need it**:Enables the Aggregator to use the Dialer/SSHTunneler to connect to the user-apiserver.
**Which issue this PR fixes** : fixes ##46679
**Special notes for your reviewer**:
**Release note**: None
Automatic merge from submit-queue (batch tested with PRs 36721, 46483, 45500, 46724, 46036)
stop special casing the loopback connection for aggregator
Fixes a TODO for the aggregator loopback connection.
Automatic merge from submit-queue
Add initializer support to admission and uninitialized filtering to rest storage
Initializers are the opposite of finalizers - they allow API clients to react to object creation and populate fields prior to other clients seeing them.
High level description:
1. Add `metadata.initializers` field to all objects
2. By default, filter objects with > 0 initializers from LIST and WATCH to preserve legacy client behavior (known as partially-initialized objects)
3. Add an admission controller that populates .initializer values per type, and denies mutation of initializers except by certain privilege levels (you must have the `initialize` verb on a resource)
4. Allow partially-initialized objects to be viewed via LIST and WATCH for initializer types
5. When creating objects, the object is "held" by the server until the initializers list is empty
6. Allow some creators to bypass initialization (set initializers to `[]`), or to have the result returned immediately when the object is created.
The code here should be backwards compatible for all clients because they do not see partially initialized objects unless they GET the resource directly. The watch cache makes checking for partially initialized objects cheap. Some reflectors may need to change to ask for partially-initialized objects.
```release-note
Kubernetes resources, when the `Initializers` admission controller is enabled, can be initialized (defaulting or other additive functions) by other agents in the system prior to those resources being visible to other clients. An initialized resource is not visible to clients unless they request (for get, list, or watch) to see uninitialized resources with the `?includeUninitialized=true` query parameter. Once the initializers have completed the resource is then visible. Clients must have the the ability to perform the `initialize` action on a resource in order to modify it prior to initialization being completed.
```
Automatic merge from submit-queue (batch tested with PRs 46239, 46627, 46346, 46388, 46524)
Dynamic webhook admission control plugin
Unit tests pass.
Needs plumbing:
* [ ] service resolver (depends on @wfender PR)
* [x] client cert (depends on ????)
* [ ] hook source (depends on @caesarxuchao PR)
Also at least one thing will need to be renamed after Chao's PR merges.
```release-note
Allow remote admission controllers to be dynamically added and removed by administrators. External admission controllers make an HTTP POST containing details of the requested action which the service can approve or reject.
```
Add support for creating resources that are not immediately visible to
naive clients, but must first be initialized by one or more privileged
cluster agents. These controllers can mark the object as initialized,
allowing others to see them.
Permission to override initialization defaults or modify an initializing
object is limited per resource to a virtual subresource "RESOURCE/initialize"
via RBAC.
Initialization is currently alpha.
Add location transformer, config for transformers
Location transformer helps choose the most specific transformer for
read/write operations depending on the path of resource being accessed.
Configuration allows use of --experimental-encryption-provider-config
to set up encryption providers. Only AEAD is supported at the moment.
Add new files to BUILD, AEAD => k8s-aes-gcm
Use group resources to select encryption provider
Update tests for configuration parsing
Remove location transformer
Allow specifying providers per resource group in configuration
Add IdentityTransformer configuration option
Fix minor issues with initial AEAD implementation
Unified parsing of all configurations
Parse configuration using a union struct
Run configuration parsing in APIserver, refactor parsing
More gdoc, fix minor bugs
Add test coverage for combined transformers
Use table driven tests for encryptionconfig
Automatic merge from submit-queue
apiserver: add a webhook implementation of the audit backend
This builds off of #45315 and is intended to implement an interfaced defined in #45766.
TODO:
- [x] Rebase on top of API types PR.
- [x] Rebase on top of API types updates (#46065)
- [x] Rebase on top of feature flag (#46009)
- [x] Rebase on top of audit instrumentation.
- [x] Hook up API server flag or register plugin (depending on #45766)
Features issue https://github.com/kubernetes/features/issues/22
Design proposal https://github.com/kubernetes/community/blob/master/contributors/design-proposals/auditing.md
```release-notes
Webhook added to the API server which omits structured audit log events.
```
/cc @soltysh @timstclair @soltysh @deads2k
Centralize the creation of the dialer during startup.
Have the dialer then passed in to both APIServer and Aggregator.
Aggregator the sets the dialer on its Transport base.
This should allow the SSTunnel to be used but also allow the Aggregation
Auth to work with it.
Depending on Environment InsecureSkipTLSVerify *may* need to be set to
true.
Fixed as few tests to call CreateDialer as part of start-up.
As part of https://github.com/kubernetes/community/pull/132, thsi commit
adds a generic webhook admission controller. This plugin allows for a
completely declarative approach for filtering/matching admission requests
and for matching admission requests, calls out to an external webhook for
handling admission requests.
Automatic merge from submit-queue (batch tested with PRs 46552, 46608, 46390, 46605, 46459)
Move admission lifecycle to genericapi
**What this PR does / why we need it**: ends the whole sequence of moving some admission plugins to generic api.
**Release note**:
```release-note
NONE
```
Automatic merge from submit-queue (batch tested with PRs 46561, 46566)
Fix golint errors in cmd/kube-apiserver
**What this PR does / why we need it**:
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #
**Special notes for your reviewer**:
**Release note**:
```release-note
```
Automatic merge from submit-queue (batch tested with PRs 45327, 46217, 46377, 46428, 46588)
Fix comment typo in kube-apiserver and cachesize
**What this PR does / why we need it**:
Fix comment typo in files cmd/kube-apiserver/app/server.go and pkg/registry/cachesize/cachesize.go
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #
Not a major issue, just a minor improvement.
**Special notes for your reviewer**:
**Release note**:
```release-note
NONE
```
lifecycle plugin: make use of the libraries under k8s.io/client-go/pkg/api and k8s.io/client-go/kubernetes
for the client libraries instead of k8s.io/kubernetes/client/*
move registration to AdmissionOptions
Automatic merge from submit-queue (batch tested with PRs 46302, 44597, 44742, 46554)
Change to aggregator so it calls a user apiservice via its pod IP.
proxy_handler now does a sideways call to lookup the pod IPs for aservice.
It will then pick a random pod IP to forward the use apiserver request to.
**What this PR does / why we need it**: It allows the aggregator to work without setting up the full network stack on the kube master (i.e. with kube-dns or kube-proxy)
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes#44619
**Special notes for your reviewer**:
**Release note**:
```release-note
```
proxy_handler now uses the endpoint router to map the cluster IP to
appropriate endpoint (Pod) IP for the given resource.
Added code to allow aggregator routing to be optional.
Updated bazel build.
Fixes to cover JLiggit comments.
Added util ResourceLocation method based on Listers.
Fixed issues from verification steps.
Updated to add an interface to obfuscate some of the routing logic.
Collapsed cluster IP resolution in to the aggregator routing
implementation.
Added 2 simple unit tests for ResolveEndpoint
Automatic merge from submit-queue
remove init blocks from all admission plugins
**What this PR does / why we need it**:
removes init blocks from all admission plugins
**Release note**:
```release-note
NONE
```
Automatic merge from submit-queue
Allow the /logs handler on the apiserver to be toggled.
Adds a flag to kube-apiserver, and plumbs through en environment variable in configure-helper.sh
Automatic merge from submit-queue (batch tested with PRs 45346, 45903, 45958, 46042, 45975)
ResourceQuota admission control injects registry
**What this PR does / why we need it**:
The `ResourceQuota` admission controller works with a registry that maps a GroupKind to an Evaluator. The registry used in the existing plug-in is not injectable, which makes usage of the ResourceQuota plug-in in other API server contexts difficult. This PR updates the code to support late injection of the registry via a plug-in initializer.
Automatic merge from submit-queue (batch tested with PRs 45247, 45810, 45034, 45898, 45899)
Apiregistration v1alpha1→v1beta1
Promoting apiregistration api from v1alpha1 to v1beta1.
API Registration is responsible for registering an API `Group`/`Version` with
another kubernetes like API server. The `APIService` holds information
about the other API server in `APIServiceSpec` type as well as general
`TypeMeta` and `ObjectMeta`. The `APIServiceSpec` type have the main
configuration needed to do the aggregation. Any request coming for
specified `Group`/`Version` will be directed to the service defined by
`ServiceReference` (on port 443) after validating the target using provided
`CABundle` or skipping validation if development flag `InsecureSkipTLSVerify`
is set. `Priority` is controlling the order of this API group in the overall
discovery document.
The return status is a set of conditions for this aggregation. Currently
there is only one condition named "Available", if true, it means the
api/server requests will be redirected to specified API server.
```release-note
API Registration is now in beta.
```
ApplyTo adds the admission chain to the server configuration the method lazily initializes a generic plugin
that is appended to the list of pluginInitializers.
apiserver.Config will hold an instance of SharedInformerFactory to ensure we only have once instance.
The field will be initialized in apisever.SecureServingOptions
Automatic merge from submit-queue
Delete "hard-coded" default value in flags usage.
**What this PR does / why we need it**:
Some flags of kubernetes components have "hard-coded" default values in their usage info. In fact, [pflag pkg](https://github.com/kubernetes/kubernetes/blob/master/vendor/github.com/spf13/pflag/flag.go#L602-L608) has already added a string `(default value)` automatically in the usage info if the flag is initialized. Then we don't need to hard-code the default value in usage info. After this PR, if we want to update the default value of a flag, we only need to update the flag where it is initialized. `pflag` will update the usage info for us. This will avoid inconsistency.
For example:
Before
```
kubelet -h
...
--node-status-update-frequency duration Specifies how often kubelet posts node status to master. Note: be cautious when changing the constant, it must work with nodeMonitorGracePeriod in nodecontroller. Default: 10s (default 10s)
...
```
After
```
kubelet -h
...
--node-status-update-frequency duration Specifies how often kubelet posts node status to master. Note: be cautious when changing the constant, it must work with nodeMonitorGracePeriod in nodecontroller. (default 10s)
...
```
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #
**Special notes for your reviewer**:
This PR doesn't delete some "hard-coded" default values because they are not explicitly initialized. We still need to hard-code them to give users friendly info.
```
--allow-privileged If true, allow containers to request privileged mode. [default=false]
```
**Release note**:
```release-note
None
```
