A.support soft link better
before this patch
  "kubectl cp" command will copy the soft link to destination as an empty regular file
after this patch
  "kubectl cp" command will behave the same as tar command
  this patch improves it on both from container and to container

B.fix some bugs
1.from container to host
  a.when copy a file ends with '/', it will cause a panic.
    for example, container gakki has a regular file /tmp/test, then run command
    kubectl cp gakki:/tmp/test/ /tmp
    panic happens
  b.when copy a file which does not exist in container, the command ends up without
    any error information

2.from host to container
  a.when run command like
    kubectl cp "" gakki:/tmp
    it will try cp current directory to container, in other words, this command works
    the same as kubectl cp . gakki:/tmp
  b.current cp command will omit an empty directory

modified:   pkg/kubectl/cmd/cp.go
modified:   pkg/kubectl/cmd/cp_test.go

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quote valid strings for field validation

**What this PR does / why we need it**:
Some of the declared const vars are empty string `""`, such as

* [`NamespaceAll`, `NamespaceNone`](https://github.com/kubernetes/kubernetes/blob/master/pkg/api/types.go#L197-L200)
* [`HostPathUnset`](https://github.com/kubernetes/kubernetes/blob/master/pkg/api/types.go#L631)

When validating such supported fields, empty string will be printed without quotes, which is kind of ugly.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #53849

**Special notes for your reviewer**:
/assign @liggitt 

**Release note**:

```release-note
None
```

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Split common e2e volume tests into two files.

Fixes #49217

Split configMap, secret, and downwardAPI tests into two files: volume
and non-volume. Prefixed volume tests with [sig-storage] and non volume
tests with [sig-api-machinery].

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Kubeadm: Add some validation for external etcd config

**What this PR does / why we need it**:
This PR add file existing check for etcd cert files.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #
fixes https://github.com/kubernetes/kubeadm/issues/342
**Special notes for your reviewer**:
Unlike issue https://github.com/kubernetes/kubeadm/issues/342 said, we already have etcd version check which include extensive validation including file format etc. This PR simply added some file existing check upfront for being more user friendly.

**Release note**:

```release-note
NONE
```

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Clean up unused func checkKnownProxyMode

**What this PR does / why we need it**:
Minor cleanup.

**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
```

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Delete redundant defination

**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
```

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Don't exit early in diff.ObjectReflectDiff on slices

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update cluster printer to enable --show-labels

**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 #53729

**Special notes for your reviewer**:

**Release note**:

```release-note
update cluster printer to enable --show-labels
```

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Update CockroachDB tag to v1.1.0

cc: @a-robinson

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Ensure base image includes the modprobe binary

**What this PR does / why we need it**:

Includes the kmod package so that "modprobe" is available for kubelet and 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 #53396

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Parse cluster-cidr only if it is specified

xref https://github.com/kubernetes/kubernetes/issues/53570#issuecomment-335943956



**What this PR does / why we need it**:

In iptables/proxier.go, there is code to check the length of the
CIDR and setup nat/iptables only if the length of the string is
greater than zero. However in PR #49087, strong validation was
added so kube proxy currently bails out and basically mandates
a valid cidr has to be specified. Let us go back to the earlier
behavior.

**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
```

split configmap, downwardapi, and secrets, into two files each volume/non-volume and moved sig labels to front of the description string

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Get rid of pkg/api/util

Old helpers we can replace with apimachinery tools.

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kubeadm: prepare for v1.9 cycle

**What this PR does / why we need it**:
Prepares kubeadm for v1.9 cycle which only supports v1.8 and v1.9 (when released). Deletes all v1.7.x support and sets minimum Kubernetes version to v1.8. 

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes 
https://github.com/kubernetes/kubeadm/issues/447
https://github.com/kubernetes/kubeadm/issues/448
https://github.com/kubernetes/kubeadm/issues/445

**Special notes for your reviewer**:
@luxas these changes seem a bit aggressive but seems reasonable given the compatibility expectations for kubeadm.

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Avoid fetching entire discovery tree when possible

For specific commands, we use discovery to determine whether a particular resource is available.

We should avoid fetching the entire discovery tree to check a single resource group version. As the number of groups grows, the performance hit and potential to encounter an error also grows.

```release-note
NONE
```

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Use bazel to build/push kubemark image

try to get some proof of concept, kubemark image is probably simple enough to get converted to bazel. (me bazel noob still trying it out locally)

cc @BenTheElder @ixdy @shyamjvs 

/release-note-none

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RBAC: Add test for create clusterrolebindding

**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
NONE
```

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generic webhook: set a default timeout for webhook requests

Add a 30 second timeout for all HTTP requests that the webhook sends
so they timeout instead of hanging forever.

closes https://github.com/kubernetes/kubernetes/issues/53698

cc @kubernetes/sig-api-machinery-pr-reviews 

```release-note
NONE
```

debian-hyperkube-base-amd64

Don't use strokes in the logo SVG

Mixing strokes and paths makes for weird scaling.  Convert the
logo-with-border to use a path.

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add RequestReceivedTimestamp and StageTimestamp to audit event

fixes https://github.com/kubernetes/kubernetes/issues/52160

**Release note**:
```
Add RequestReceivedTimestamp and StageTimestamp with micro seconds to audit events.
```

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Mark etcd-quorum-read as deprecated.

**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 #
ref: #53662 ##53717

**Special notes for your reviewer**:
/cc @liggitt @dims @anguslees 

**Release note**:

```release-note
Deprecation: The flag `etcd-quorum-read ` of kube-apiserver is deprecated and the ability to switch off quorum read will be removed in a future release.
```

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Reduce log spam in qos container manager

**What this PR does / why we need it**:
excessive log stmts make it hard to debug actual problems.

**Release note**:
```release-note
NONE
```

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Improve e2e tests of audit logging.

Now test includes:
 * Verbs: create, list, watch, delete, get, update, patch.
 * Resources: pods, deployments, secrets, config maps, custom resource
 definition.
 * More fields: user, resource, level, stage, presence of request and
 response objects.

Fixes #49653

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Update comments in pkg/kubeapiserver/authenticator/config.go

**What this PR does / why we need it**:
Make the comments consistent with the function signatures

**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
```

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User separate client for leader election in scheduler

Ref https://github.com/kubernetes/kubernetes/issues/53327

@kubernetes/sig-scheduling-bugs @bsalamat @davidopp 

```release-note
Use separate client for leader election in scheduler to avoid starving leader election by regular scheduler operations.
```

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[GCE kube-up] Allow creating/deleting custom network

**What this PR does / why we need it**:
From https://github.com/kubernetes/test-infra/issues/4472.

This is the first step to make PR jobs use custom network instead of auto network (so that we will be less likely hitting subnetwork quota issue). 

The last commit is purely for testing out the changes on PR jobs. It will be removed after review.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #NONE.

**Special notes for your reviewer**:
/assign @bowei @nicksardo 

**Release note**:

```release-note
NONE
```

Now test includes:
 * Verbs: create, list, watch, delete, get, update, patch.
 * Resources: pods, deployments, secrets, config maps, custom resource
 definition.
 * More fields: user, resource, level, stage, presence of request and
 response objects.

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Add a flag to customize config relative dir

So while migrating nodee2e configs to test-infra, I found out that I'd need to have a better support for [user-data](https://github.com/kubernetes/test-infra/blob/master/jobs/e2e_node/image-config.yaml#L11). However it's not wise to use an [absolute path](https://github.com/kubernetes/test-infra/blob/master/jobs/config.json#L9309), having the config dir to be configurable will be a better solution here, and as well for later on support run local node tests from test-infra.

Currently the job references to the image configs from test-infra, but read metadata from kubernetes, which is wrong :-\


/assign @yguo0905 @Random-Liu