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Fix autoscaling API documentation
**What this PR does / why we need it**:
This PR fixes the API documentation generated for HorizontalPodAutoscaler resource.
**Which issue(s) this PR fixes**:
The current API doc for `MetricSpec` and `MetricStatus` is confusing. Users get no idea what can be used as the value for the `type` field, because the doc says this:
```
type is the type of metric source. It should match one of the fields below.
```
While acceptable in the source code, it makes no senses when reading the API doc, especially when the "`type`" field is listed as the last row in a table (see: https://kubernetes.io/docs/api-reference/v1.8/#metricspec-v2beta1-autoscaling )
**Special notes for your reviewer**:
This PR makes no changes to the code behavior.
**Release note**:
```release-note
NONE
```
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cleanup useless functions
cleanup some useless functions, for they get no references from others during my search. Please remind me if I'm wrong.
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Allow FlexVolume PV secret namespaces
Completes the secret namespace PV refactor, so all PV volume sources that specify secrets can reference them outside the PVC namespace.
Finished the secret-related aspect of https://github.com/kubernetes/kubernetes/issues/32131
```release-note
PersistentVolume flexVolume sources can now reference secrets in a namespace other than the PersistentVolumeClaim's namespace.
```
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fix comment about PodAffinityTerm in api
**Release note**:
```release-note
NONE
```
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Remove incorrect dead code.
TolerationToleratesTaint was incorrect: if the toleration.Key is empty and
taint is non-empty, it should not return false. It was also not used anywhere.
The correct implementations are in staging/src/k8s.io/api/core/v1/toleration.go
and pkg/apis/core/v1/helper/helpers.go
**Release note**:
```release-note
NONE
```
/sig scheduling
/sig api-machinery
/kind bug
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New API group for Events.
Fixkubernetes/features#383
cc @shyamjvs
```release-note
Add events.k8s.io api group with v1beta1 API containing redesigned Event type.
```
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Expose single annotation/label via downward API
**What this PR does / why we need it**:
https://github.com/kubernetes/community/blob/master/contributors/design-proposals/node/annotations-downward-api.md
Support exposing single annotation via both env and volume downward API using the following syntax:
```
metadata.annotations['key']
metadata.labels['key']
```
**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #
#31218
**Special notes for your reviewer**:
This PR takes over the work in https://github.com/kubernetes/kubernetes/pull/41648.
**Release note**:
```
A single value in metadata.annotations/metadata.labels can be passed into the containers via Downward API
```
/assign @thockin @vishh
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Removed opaque integer resources (deprecated in v1.8)
**What this PR does / why we need it**:
* Remove opaque integer resources (OIR) support from the code base. This feature was deprecated in v1.8 and replaced by Extended Resources (ER).
**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes#55102
**Release note**:
```release-note
Remove opaque integer resources (OIR) support (deprecated in v1.8.)
```
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Initial basic bootstrap-checkpoint support
**What this PR does / why we need it**:
Adds initial support for Pod checkpointing to allow for controlled recovery of the control plane during self host failure conditions.
fixes#49236
xref https://github.com/kubernetes/features/issues/378
**Special notes for your reviewer**:
Proposal is here: https://docs.google.com/document/d/1hhrCa_nv0Sg4O_zJYOnelE8a5ClieyewEsQM6c7-5-o/edit?ts=5988fba8#
1. Controlled tests work, but I have not tested the self hosted api-server recovery, that requires validation and logs. /cc @luxas
2. In adding hooks for checkpoint manager much of the tests around basicpodmanager appears to be stub'd. This has become an anti-pattern in the code and should be avoided.
3. I need a node-e2e to ensure consistency of behavior.
**Release note**:
```
Add basic bootstrap checkpointing support to the kubelet for control plane recovery
```
/cc @kubernetes/sig-cluster-lifecycle-misc @kubernetes/sig-node-pr-reviews
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Add Custom Pod DNS to Kubernetes API
**What this PR does / why we need it**:
Ref:
- Feature issue: https://github.com/kubernetes/features/issues/504
- Proposal: https://github.com/kubernetes/community/pull/1276
This PR adds the relevant APIs, validation check and the underlying kubelet changes.
**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #NONE
**Special notes for your reviewer**:
/sig network
@kubernetes/sig-network-api-reviews
/assign @bowei @thockin
**Release note**:
```release-note
Add DNSConfig field to PodSpec and support "None" mode for DNSPolicy (Alpha).
```
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ResourceQuota support for Hugepages
**What this PR does / why we need it**:
Hugepage resourceQuota support
**Which issue this PR fixes**
fixes#53672 ResourceQuota part
**Special notes for your reviewer**:
What I'm concerned most is the change in quota evaluator:
Rather than add check especially for resource hugage, I would prefer add a check list, that could be easily extended by adding corresponding prefix into the list (As far as I know, pluginResources will also support ResourceQuota in later versions)
@derekwaynecarr What's your opinion?
/cc @derekwaynecarr
**Release note**:
```release-note
NONE
```
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Refactor iSCSI PV spec to use SecretReference
**What this PR does / why we need it**:
Use SecretReference in iSCSI PV spec
**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-incubator/external-storage/issues/321
**Special notes for your reviewer**:
@liggitt
**Release note**:
```release-note
iSCSI Persistent Volume Sources can now reference CHAP Secrets in namespaces other than the namespace of the bound Persistent Volume Claim
```
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Clarify ExternalNames are hostnames
Updates the documentation for ExternalName to clarify
that they adhere RFC-1123 hostname and are not DNS names.
Fixes#52266
**Release note**:
```release-note
```
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If mountPath is missing, prefix with root dir.
If `mountPath` is not absolute, add the os-specific root directory as a prefix.
Ref: https://github.com/kubernetes/kubernetes/pull/51240https://groups.google.com/forum/#!topic/kubernetes-sig-storage/k_0Wr2kYkpU
@thockin @saad-ali @andyzhangx
Note to @thockin I left the validation in place, in seems like it is a net win, since it will give a decent
error message to most people, but the fall-back defaulting is there if it doesn't catch 'c:'
I'm happy to rip out the validation if that is preferable to everyone. Let me know.
```release-note
If a non-absolute mountPath is passed to the kubelet, prefix it with the appropriate root path.
```
