Fold concept overview pages into section indexes

Where an existing Concept section has an index and the first page is
“Overview of X”, move the content of that overview into the index page
itself.

Also, configure redirects accordingly.

Author: Tim Bannister

content/en/docs/concepts/cluster-administration/_index.md

@@ -1,7 +1,71 @@
 ---
-title: "Cluster Administration"
+title: Cluster Administration
+reviewers:
+- davidopp
+- lavalamp
 weight: 100
+content_type: concept
 description: >
   Lower-level detail relevant to creating or administering a Kubernetes cluster.
 ---
 
+<!-- overview -->
+The cluster administration overview is for anyone creating or administering a Kubernetes cluster.
+It assumes some familiarity with core Kubernetes [concepts](/docs/concepts/).
+
+
+<!-- body -->
+## Planning a cluster
+
+See the guides in [Setup](/docs/setup/) for examples of how to plan, set up, and configure Kubernetes clusters. The solutions listed in this article are called *distros*.
+
+Before choosing a guide, here are some considerations:
+
+ - Do you just want to try out Kubernetes on your computer, or do you want to build a high-availability, multi-node cluster? Choose distros best suited for your needs.
+ - Will you be using **a hosted Kubernetes cluster**, such as [Google Kubernetes Engine](https://cloud.google.com/kubernetes-engine/), or **hosting your own cluster**?
+ - Will your cluster be **on-premises**, or **in the cloud (IaaS)**? Kubernetes does not directly support hybrid clusters. Instead, you can set up multiple clusters.
+ - **If you are configuring Kubernetes on-premises**, consider which [networking model](/docs/concepts/cluster-administration/networking/) fits best.
+ - Will you be running Kubernetes on **"bare metal" hardware** or on **virtual machines (VMs)**?
+ - Do you **just want to run a cluster**, or do you expect to do **active development of Kubernetes project code**? If the
+   latter, choose an actively-developed distro. Some distros only use binary releases, but
+   offer a greater variety of choices.
+ - Familiarize yourself with the [components](/docs/admin/cluster-components/) needed to run a cluster.
+
+Note: Not all distros are actively maintained. Choose distros which have been tested with a recent version of Kubernetes.
+
+## Managing a cluster
+
+* [Managing a cluster](/docs/tasks/administer-cluster/cluster-management/) describes several topics related to the lifecycle of a cluster: creating a new cluster, upgrading your cluster’s master and worker nodes, performing node maintenance (e.g. kernel upgrades), and upgrading the Kubernetes API version of a running cluster.
+
+* Learn how to [manage nodes](/docs/concepts/nodes/node/).
+
+* Learn how to set up and manage the [resource quota](/docs/concepts/policy/resource-quotas/) for shared clusters.
+
+## Securing a cluster
+
+* [Certificates](/docs/concepts/cluster-administration/certificates/) describes the steps to generate certificates using different tool chains.
+
+* [Kubernetes Container Environment](/docs/concepts/containers/container-environment/) describes the environment for Kubelet managed containers on a Kubernetes node.
+
+* [Controlling Access to the Kubernetes API](/docs/reference/access-authn-authz/controlling-access/) describes how to set up permissions for users and service accounts.
+
+* [Authenticating](/docs/reference/access-authn-authz/authentication/) explains authentication in Kubernetes, including the various authentication options.
+
+* [Authorization](/docs/reference/access-authn-authz/authorization/) is separate from authentication, and controls how HTTP calls are handled.
+
+* [Using Admission Controllers](/docs/reference/access-authn-authz/admission-controllers/) explains plug-ins which intercepts requests to the Kubernetes API server after authentication and authorization.
+
+* [Using Sysctls in a Kubernetes Cluster](/docs/concepts/cluster-administration/sysctl-cluster/) describes to an administrator how to use the `sysctl` command-line tool to set kernel parameters .
+
+* [Auditing](/docs/tasks/debug-application-cluster/audit/) describes how to interact with Kubernetes' audit logs.
+
+### Securing the kubelet
+  * [Master-Node communication](/docs/concepts/architecture/master-node-communication/)
+  * [TLS bootstrapping](/docs/reference/command-line-tools-reference/kubelet-tls-bootstrapping/)
+  * [Kubelet authentication/authorization](/docs/admin/kubelet-authentication-authorization/)
+
+## Optional Cluster Services
+
+* [DNS Integration](/docs/concepts/services-networking/dns-pod-service/) describes how to resolve a DNS name directly to a Kubernetes service.
+
+* [Logging and Monitoring Cluster Activity](/docs/concepts/cluster-administration/logging/) explains how logging in Kubernetes works and how to implement it.

content/en/docs/concepts/cluster-administration/cluster-administration-overview.md

@@ -1,5 +1,5 @@
 ---
-title: "Containers"
+title: Containers
 weight: 40
 description: Technology for packaging an application along with its runtime dependencies.
 reviewers:
@@ -8,3 +8,37 @@ reviewers:
 content_type: concept
 ---
 
+<!-- overview -->
+
+Each container that you run is repeatable; the standardization from having
+dependencies included means that you get the same behavior wherever you
+run it.
+
+Containers decouple applications from underlying host infrastructure.
+This makes deployment easier in different cloud or OS environments.
+
+
+
+
+<!-- body -->
+
+## Container images
+A [container image](/docs/concepts/containers/images/) is a ready-to-run
+software package, containing everything needed to run an application:
+the code and any runtime it requires, application and system libraries,
+and default values for any essential settings.
+
+By design, a container is immutable: you cannot change the code of a
+container that is already running. If you have a containerized application
+and want to make changes, you need to build a new container that includes
+the change, then recreate the container to start from the updated image.
+
+## Container runtimes
+
+{{< glossary_definition term_id="container-runtime" length="all" >}}
+
+## {{% heading "whatsnext" %}}
+
+* Read about [container images](/docs/concepts/containers/images/)
+* Read about [Pods](/docs/concepts/workloads/pods/)
+