Added documentation for Metrics Server #5560
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| - Kubernetes components to operate (e.g. autoscalers to automatically scale user applications) | ||
| - Kubernetes users to understand their applications behavior | ||
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I think it's better to give more examples and less ambiguous phrases
Starting from Kubernetes 1.8, resource usage metrics, such as container CPU and memory usage,
are available in Kubernetes though the Metrics API. These metrics can be either accessed directly
by user, for example by using `kubectl top` command, or used by a controller in the cluster, e.g.
Horizontal Pod Autoscaler to make decisions.
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| Metrics API provides current resource usage metrics for pods and nodes. It doesn't offer historical metrics, so one needs to | ||
| archive metrics themselves. In the future Historical API might be defined but it will not be implemented as a part of | ||
| the core metrics pipeline. |
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I think reference to historical metrics or Historical API requires context which user might not have at this point. I'm not eve sure it's worth mentioning.
What about something like this?
Through Metrics API you can get the amount of resource currently used
by a given node or a given pod. This API doesn't store the metric values,
so it's not possible for example to get the amount of resources used by a
given node 10 minutes ago.
| the core metrics pipeline. | ||
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| The API is discoverable through the same endpoint as the other Kubernetes APIs under `/apis/metrics.k8s.io/` path. | ||
| It also offers the same security, scalability and reliability guarantees. |
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What this paragraph is saying this API is no different from any other API. Is it worth mentioning explicitly?
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Question: is metrics API currently enabled by default? I'm assuming an explicit argument to --runtime-config.
It is also confusing that there wasn't such an API before v1.8, then suddenly we have both v1alpha1 and v1beta1 to choose from ... (based on the API link mentioned below).
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@crassirostris done
@tengqm The API was defined in alpha ~Q2'16, so quite some time ago and implemented in Heapster. This was not the right way of implementing the API though, so in Q2'17 we designed an implemented metrics-server, which is the proper way of implementing the API. Then it was graduated to beta and metrics-server became enabled by default in Kubernetes in 1.8.
As the API is not implemented by API server it's requires metrics-server to be deployed to Kubernetes. As metric s-server was not deployed by default before v1.8 we haven't seen the API there.
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Thanks for the background. I just learned that a metrics-server have to be deployed with its API (APIService) registered to the kube-aggregator (or just kube-apiserver) for discovery.
| It also offers the same security, scalability and reliability guarantees. | ||
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| The API is defined in [k8s.io/metrics](https://github.com/kubernetes/metrics/tree/master/pkg/apis/metrics) repository, | ||
| where the detailed semantic is explained. |
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Metrics API is defined in [k8s.io/metrics](https://github.com/kubernetes/metrics/tree/master/pkg/apis/metrics) repository.
You can find more information there.
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As a user or an operator, what am I supposed to read from the provided API link? Can we provide some precise, consumable information here instead of pointing the readers to the source code repo?
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@crassirostris done
@tengqm my goal is to show how the resources look like. Any idea how to do it better?
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I was looking forward to some concrete examples. Such as "here is an example to show current memory utilization on node A" and "here is another example showing the current CPU utilization of Pod B". We teach users/operators how to use it and give them a taste of the output. I'm afraid not all readers are familiar with Golang and even they do, they have to have some API design knowledge to understand the source code.
| The API is defined in [k8s.io/metrics](https://github.com/kubernetes/metrics/tree/master/pkg/apis/metrics) repository, | ||
| where the detailed semantic is explained. | ||
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| ### Supported endpoints |
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Shouldn't it be about resources, not paths? Paths are just implementation detail, especially the difference between /nodes and /nodes/{node}.
Anyway, that is certainly not something that should be in the Tasks category, IMO link to the API in the previous paragraph is enough.
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| ## Metrics Server | ||
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| [Metrics Server](https://github.com/kubernetes-incubator/metrics-server) is a cluster-wide aggregator of monitoring data. |
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Not any monitoring data, only the resource usage metrics
| ## Metrics Server | ||
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| [Metrics Server](https://github.com/kubernetes-incubator/metrics-server) is a cluster-wide aggregator of monitoring data. | ||
| Starting from Kubernetes 1.8 it's work on all Kubernetes setups |
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Starting from Kubernetes 1.8 it's deployed by default in all Kubernetes setups
Is it really? What about e.g. kopf?
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Would it be useful to include steps for the user to deploy the metrics server themselves, if it is not deployed by default (for ex on pre-1.8 cluster)?
Also how can a user verify/debug that it is running? Should they run kubectl get deployments and expect to see a specific deployment?
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Agreed. A complete story would be more useful.
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| [Metrics Server](https://github.com/kubernetes-incubator/metrics-server) is a cluster-wide aggregator of monitoring data. | ||
| Starting from Kubernetes 1.8 it's work on all Kubernetes setups | ||
| and runs as a pod in a user space (on one of the nodes), similar to how any Kubernetes application would run. |
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I think just saying it's deployed to the Kubernetes cluster as a Deployment object is enough
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| It discovers all nodes in the cluster and queries usage information from Summary API exposed by [Kubelet](/docs/admin/kubelet/)s. | ||
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| Metrics Server use the same authorization/authentication mechanism as the main API server. It's registered there through |
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- uses*
- Why even mention auth[nz] here? It's not important in the context of this doc. The important part (and even this is arguable) that it actually serves the requests send to the Kubernetes API
- Are you sure it uses the same auth[nz]? I'm pretty sure it doesn't use authz webhook installed on a master machine
| Starting from Kubernetes 1.8 it's work on all Kubernetes setups | ||
| and runs as a pod in a user space (on one of the nodes), similar to how any Kubernetes application would run. | ||
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| It discovers all nodes in the cluster and queries usage information from Summary API exposed by [Kubelet](/docs/admin/kubelet/)s. |
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Metric server collects metrics from the Summary API, exposed by [Kubelet](/docs/admin/kubelet/) on each node.
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What is summary API? The link provided (https://kubernetes.io/docs/admin/kubelet/) is not providing a definition or example of this API.
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@crassirostris done
@tengqm I'm not sure whether there is any documentation for Summary API.
cc @dashpole @yujuhong
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do you mean the metrics endpoint https://<NODE_IP>:10250/metrics ?
I'm 100% sure the term "Summary API" never showed up anywehre on http://kubernetes.io/docs/
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I mean https://<NODE_IP>:10255/stats/summary
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I'm not sure whether there is any documentation for Summary API.
Not that I know of...
Would provide the actual API help? https://github.com/kubernetes/kubernetes/blob/master/pkg/kubelet/apis/stats/v1alpha1/types.go
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@piosz I agree with the comments by @crassirostris. |
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I would suggest "The Metrics API" instead of "Metrics API." That seems to be the pattern elsewhere in the docs. |
| the core metrics pipeline. | ||
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| The API is discoverable through the same endpoint as the other Kubernetes APIs under `/apis/metrics.k8s.io/` path. | ||
| It also offers the same security, scalability and reliability guarantees. |
There was a problem hiding this comment.
Question: is metrics API currently enabled by default? I'm assuming an explicit argument to --runtime-config.
It is also confusing that there wasn't such an API before v1.8, then suddenly we have both v1alpha1 and v1beta1 to choose from ... (based on the API link mentioned below).
| It also offers the same security, scalability and reliability guarantees. | ||
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| The API is defined in [k8s.io/metrics](https://github.com/kubernetes/metrics/tree/master/pkg/apis/metrics) repository, | ||
| where the detailed semantic is explained. |
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As a user or an operator, what am I supposed to read from the provided API link? Can we provide some precise, consumable information here instead of pointing the readers to the source code repo?
| ## Metrics Server | ||
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| [Metrics Server](https://github.com/kubernetes-incubator/metrics-server) is a cluster-wide aggregator of monitoring data. | ||
| Starting from Kubernetes 1.8 it's work on all Kubernetes setups |
There was a problem hiding this comment.
Agreed. A complete story would be more useful.
| Starting from Kubernetes 1.8 it's work on all Kubernetes setups | ||
| and runs as a pod in a user space (on one of the nodes), similar to how any Kubernetes application would run. | ||
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| It discovers all nodes in the cluster and queries usage information from Summary API exposed by [Kubelet](/docs/admin/kubelet/)s. |
There was a problem hiding this comment.
What is summary API? The link provided (https://kubernetes.io/docs/admin/kubelet/) is not providing a definition or example of this API.
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@crassirostris @tengqm @steveperry-53 comments addressed. PTAL |
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| Starting from Kubernetes 1.8, resource usage metrics, such as container CPU and memory usage, | ||
| are available in Kubernetes though the the Metrics API. These metrics can be either accessed directly |
| Starting from Kubernetes 1.8, resource usage metrics, such as container CPU and memory usage, | ||
| are available in Kubernetes though the the Metrics API. These metrics can be either accessed directly | ||
| by user, for example by using `kubectl top` command, or used by a controller in the cluster, e.g. | ||
| Horizontal Pod Autoscaler to make decisions. |
| It also offers the same security, scalability and reliability guarantees. | ||
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| The API is defined in [k8s.io/metrics](https://github.com/kubernetes/metrics/blob/master/pkg/apis/metrics/v1beta1/types.go) | ||
| repository. You can find more information about the API resources there. |
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about the API resources there
Maybe about the API there?
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| The API no different from any other API: | ||
| it is discoverable through the same endpoint as the other Kubernetes APIs under `/apis/metrics.k8s.io/` path. | ||
| It also offers the same security, scalability and reliability guarantees. |
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List intended?
Also, IMO also is extra here :) Especially with the list
| ## Metrics Server | ||
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| [Metrics Server](https://github.com/kubernetes-incubator/metrics-server) is a cluster-wide aggregator of resource usage data. | ||
| Starting from Kubernetes 1.8 it's deployed by default in clusters crated by `kube-up.sh` script |
| [Metrics Server](https://github.com/kubernetes-incubator/metrics-server) is a cluster-wide aggregator of resource usage data. | ||
| Starting from Kubernetes 1.8 it's deployed by default in clusters crated by `kube-up.sh` script | ||
| as a Deployment object. | ||
| User can deploy it also using the provided [deployment yamls](https://github.com/kubernetes-incubator/metrics-server/tree/master/deploy). |
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AFAIR the recommendation is to talk to user instead of referencing it in a third person, i.e. You can deploy...
Please remove also
Why new line? That'll end up as one paragraph anyway
| The API is defined in [k8s.io/metrics](https://github.com/kubernetes/metrics/blob/master/pkg/apis/metrics/v1beta1/types.go) | ||
| repository. You can find more information about the API resources there. | ||
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| ## Metrics Server |
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I realize that I don't understand whether the metrics API will be available without metric server I won't, right?
I think it's pretty important "detail", if true
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Yes, it won't. Added an info about this above.
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PTAL |
| The API is defined in [k8s.io/metrics](https://github.com/kubernetes/metrics/blob/master/pkg/apis/metrics/v1beta1/types.go) | ||
| repository. You can find more information about the API there. | ||
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| The API requires metrics server to be deployed in the cluster. Otherwise it will be not available. |
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I think those two sentences have the same meaning. What about leaving only one?
Smth like **Note:** The Metrics API is not available unless the Metric Server is deployed in the cluster.
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Comments addressed. Commits squashed. @crassirostris could you please apply LGTM label? |
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/lgtm If that doesn't work, please apply it yourself, I don't have the rights to do so |
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@steveperry-53 PTAL |
* GC now supports non-core resources * Add two examples about how to analysis audits of kube-apiserver (#4264) * Deprecate system:nodes binding * [1.8] StatefulSet `initialized` annotation is now ignored. * inits the kubeadm upgrade docs addresses /issues/4689 * adds kubeadm upgrade cmd to ToC addresses /issues/4689 * add workload placement docs * ScaleIO - document udpate for 1.8 * Add documentation on storageClass.mountOptions and PV.mountOptions (#5254) * Add documentation on storageClass.mountOptions and PV.mountOptions * convert notes into callouts * Add docs for CustomResource validation add info about supported fields * advanced audit beta features (#5300) * Update job workload doc with backoff failure policy (#5319) Add to the Jobs documentation how to use the new backoffLimit field that limit the number of Pod failure before considering the Job as failed. * Documented additional AWS Service annotations (#4864) * Add device plugin doc under concepts/cluster-administration. (#5261) * Add device plugin doc under concepts/cluster-administration. * Update device-plugins.md * Update device-plugins.md Add meta description. Fix typo. Change bare metal deployment to manual deployment. * Update device-plugins.md Fix typo again. * Update page.version. (#5341) * Add documentation on storageClass.reclaimPolicy (#5171) * [Advanced audit] use new herf for audit-api (#5349) This tag contains all the changes in v1beta1 version. Update it now. * Added documentation around creating the InitializerConfiguration for the persistent volume label controller in the cloud-controller-manager (#5255) * Documentation for kubectl plugins (#5294) * Documentation for kubectl plugins * Update kubectl-plugins.md * Update kubectl-plugins.md * Updated CPU manager docs to match implementation. (#5332) * Noted limitation of alpha static cpumanager. * Updated CPU manager docs to match implementation. - Removed references to CPU pressure node condition and evictions. - Added note about new --cpu-manager-reconcile-period flag. - Added note about node allocatable requirements for static policy. - Noted limitation of alpha static cpumanager. * Move cpu-manager task link to rsc mgmt section. * init containers annotation removed in 1.8 (#5390) * Add documentation for TaintNodesByCondition (#5352) * Add documentation for TaintNodesByCondition * Update nodes.md * Update taint-and-toleration.md * Update daemonset.md * Update nodes.md * Update taint-and-toleration.md * Update daemonset.md * Fix deployments (#5421) * Document extended resources and OIR deprecation. (#5399) * Document extended resources and OIR deprecation. * Updated extended resources doc per reviews. * reverts extra spacing in _data/tasks.yml * addresses `kubeadm upgrade` review comments Feedback from @chenopis, @luxas, and @steveperry-53 addressed with this commit * HugePages documentation (#5419) * Update cpu-management-policies.md (#5407) Fixed the bad link. Modified "cpu" to "CPU". Added more 'yaml' as supplement. * Update RBAC docs for v1 (#5445) * Add user docs for pod priority and preemption (#5328) * Add user docs for pod priority and preemption * Update pod-priority-preemption.md * More updates * Update docs/admin/kubeadm.md for 1.8 (#5440) - Made a couple of minor wording changes (not strictly 1.8 related). - Did some reformatting (not strictly 1.8 related). - Updated references to the default token TTL (was infinite, now 24 hours). - Documented the new `--discovery-token-ca-cert-hash` and `--discovery-token-unsafe-skip-ca-verification` flags for `kubeadm join`. - Added references to the new `--discovery-token-ca-cert-hash` flag in all the default examples. - Added a new _Security model_ section that describes the security tradeoffs of the various discovery modes. - Documented the new `--groups` flag for `kubeadm token create`. - Added a note of caution under _Automating kubeadm_ that references the _Security model_ section. - Updated the component version table to drop 1.6 and add 1.8. - Update `_data/reference.yml` to try to get the sidebar fixed up and more consistent with `kubefed`. * Update StatefulSet Basics for 1.8 release (#5398) * addresses `kubeadm upgrade` review comments 2nd iteration review comments by @luxas * adds kubelet upgrade section to kubeadm upgrade * Fix a bulleted list on docs/admin/kubeadm.md. (#5458) I updated this doc yesterday and I was absolutely sure I fixed this, but I just saw that this commit got lost somehow. This was introduced recently in #5440. * Clarify the API to check for device plugins * Moving Flexvolume to separate out-of-tree section * addresses `kubeadm upgrade` review comments CC: @luxas * fixes kubeadm upgrade index * Update Stackdriver Logging documentation (#5495) * Re-update WordPress and MySQL PV doc to use apps/v1beta2 APIs (#5526) * Update statefulset concepts doc to use apps/v1beta2 APIs (#5420) * add document on kubectl's behavior regarding initializers (#5505) * Update docs/admin/kubeadm.md to cover self-hosting in 1.8. (#5497) This is a new beta feature in 1.8. * Update kubectl patch doc to use apps/v1beta2 APIs (#5422) * [1.8] Update "Run Applications" tasks to apps/v1beta2. (#5525) * Update replicated stateful application task for 1.8. * Update single instance stateful app task for 1.8. * Update stateless app task for 1.8. * Update kubectl patch task for 1.8. * fix the link of persistent storage (#5515) * update the admission-controllers.md index.md what-is-kubernetes.md link * fix the link of persistent storage * Add quota support for local ephemeral storage (#5493) * Add quota support for local ephemeral storage update the doc to this alpha feature * Update resource-quotas.md * Updated Deployments concepts doc (#5491) * Updated Deployments concepts doc * Addressed comments * Addressed more comments * Modify allocatable storage to ephemeral-storage (#5490) Update the doc to use ephemeral-storage instead of storage * Revamped concepts doc for ReplicaSet (#5463) * Revamped concepts doc for ReplicaSet * Minor changes to call out specific versions for selector defaulting and immutability * Addressed doc review comments * Remove petset documentations (#5395) * Update docs to use batch/v1beta1 cronjobs (#5475) * add federation job doc (#5485) * add federation job doc * Update job.md Edits for clarity and consistency * Update job.md Fixed a typo * update DaemonSet concept for 1.8 release (#5397) * update DaemonSet concept for 1.8 release * Update daemonset.md Fix typo. than -> then * Update bootstrap tokens doc for 1.8. (#5479) * Update bootstrap tokens doc for 1.8. This has some changes I missed when I was updating the main kubeadm documention: - Bootstrap tokens are now beta, not alpha (kubernetes/enhancements#130) - The apiserver flag to enable the authenticator changedin 1.8 (kubernetes/kubernetes#51198) - Added `auth-extra-groups` documentaion (kubernetes/kubernetes#50933) - Updated the _Token Management with `kubeadm`_ section to link to the main kubeadm docs, since it was just duplicated information. * Update bootstrap-tokens.md * Updated the Cassandra tutorial to use apps/v1beta2 (#5548) * add docs for AllowPrivilegeEscalation (#5448) Signed-off-by: Jess Frazelle <acidburn@microsoft.com> * Add local ephemeral storage alpha feature in managing compute resource (#5522) * Add local ephemeral storage alpha feature in managing compute resource Since 1.8, we add the local ephemeral storage alpha feature as one resource type to manage. Add this feature into the doc. * Update manage-compute-resources-container.md * Update manage-compute-resources-container.md * Update manage-compute-resources-container.md * Update manage-compute-resources-container.md * Update manage-compute-resources-container.md * Update manage-compute-resources-container.md * Added documentation for Metrics Server (#5560) * authorization: improve authorization debugging docs (#5549) * Document mount propagation (#5544) * Update /docs/setup/independent/create-cluster-kubeadm.md for 1.8. (#5524) This introduction needed a couple of small tweaks to cover the `--discovery-token-ca-cert-hash` flag added in kubernetes/kubernetes#49520 and some version bumps. * Add task doc for alpha dynamic kubelet configuration (#5523) * Fix input/output of selfsubjectaccess review (#5593) * Add docs for implementing resize (#5528) * Add docs for implementing resize * Update admission-controllers.md * Added link to PVC section * minor typo fixes * Update NetworkPolicy concept guide with egress and CIDR changes (#5529) * update zookeeper tutorial for 1.8 release * add doc for hostpath type (#5503) * Federated Hpa feature doc (#5487) * Federated Hpa feature doc * Federated Hpa feature doc review fixes * Update hpa.md * Update hpa.md * update cloud controller manager docs for v1.8 * Update cronjob with defaults information (#5556) * Kubernetes 1.8 reference docs (#5632) * Kubernetes 1.8 reference docs * Kubectl reference docs for 1.8 * Update side bar with 1.8 kubectl and api ref docs links * remove petset.md * update on state of HostAlias in 1.8 with hostNetwork Pod support (#5644) * Fix cron job deletion section (#5655) * update imported docs (#5656) * Add documentation for certificate rotation. (#5639) * Link to using kubeadm page * fix the command output fix the command output * fix typo in api/resources reference: "Worloads" * Add documentation for certificate rotation. * Create TOC entry for cloud controller manager. (#5662) * Updates for new versions of API types * Followup 5655: fix link to garbage collection (#5666) * Temporarily redirect resources-reference to api-reference. (#5668) * Update config for 1.8 release. (#5661) * Update config for 1.8 release. * Address reviewer comments. * Switch references in HPA docs from alpha to beta (#5671) The HPA docs still referenced the alpha version. This switches them to talk about v2beta1, which is the appropriate version for Kubernetes 1.8 * Deprecate openstack heat (#5670) * Fix typo in pod preset conflict example Move container port definition to the correct line. * Highlight openstack-heat provider deprecation The openstack-heat provider for kube-up is being deprecated and will be removed in a future release. * Temporarily fix broken links by redirecting. (#5672) * Fix broken links. (#5675) * Fix render of code block (#5674) * Fix broken links. (#5677) * Add a small note about auto-bootstrapped CSR ClusterRoles (#5660) * Update kubeadm install doc for v1.8 (#5676) * add draft workloads api content for 1.8 (#5650) * add draft workloads api content for 1.8 * edits per review, add tables, for 1.8 workloads api doc * fix typo * Minor fixes to kubeadm 1.8 upgrade guide. (#5678) - The kubelet upgrade instructions should be done on every host, not just worker nodes. - We should just upgrade all packages, instead of calling out kubelet specifically. This will also upgrade kubectl, kubeadm, and kubernetes-cni, if installed. - Draining nodes should also ignore daemonsets, and master errors can be ignored. - Make sure that the new kubeadm download is chmoded correctly. - Add a step to run `kubeadm version` to verify after downloading. - Manually approve new kubelet CSRs if rotation is enabled (known issue). * Release 1.8 (#5680) * Fix versions for 1.8 API ref docs * Updates for 1.8 kubectl reference docs * Kubeadm /docs/admin/kubeadm.md cleanup, editing. (#5681) * Update docs/admin/kubeadm.md (mostly 1.8 related). This is Fabrizio's work, which I'm committing along with my edits (in a commit on top of this). * A few of my own edits to clarify and clean up some Markdown.
ref kubernetes/enhancements#271
This change is