Update docs for agent managed by fleet on kubernetes

docs/en/ingest-management/elastic-agent/elastic-agent.asciidoc

@@ -16,7 +16,7 @@ To learn how to install, configure, and run your {agent}s, see:
 * <<elastic-agent-installation>>
 * <<uninstall-elastic-agent>>
 * <<run-elastic-agent-standalone>>
-//* <<running-on-kubernetes>>
+* <<running-on-kubernetes-managed-by-fleet>>
 * <<running-on-kubernetes-standalone>>
 * <<upgrade-elastic-agent>>
 * <<start-elastic-agent>>
@@ -31,7 +31,7 @@ include::uninstall-elastic-agent.asciidoc[leveloffset=+1]
 
 include::run-elastic-agent-standalone.asciidoc[leveloffset=+1]
 
-//include::running-on-kubernetes.asciidoc[leveloffset=+1]
+include::running-on-kubernetes-managed-by-fleet.asciidoc[leveloffset=+1]
 
 include::running-on-kubernetes-standalone.asciidoc[leveloffset=+1]
 

docs/en/ingest-management/elastic-agent/running-on-kubernetes-managed-by-fleet.asciidoc

@@ -0,0 +1,152 @@
+[[running-on-kubernetes-managed-by-fleet]]
+[role="xpack"]
+= Run {agent} on Kubernetes managed by {fleet}
+
+Use {agent} https://www.docker.elastic.co/r/beats/elastic-agent[Docker images] on Kubernetes to
+retrieve cluster metrics.
+
+ifeval::["{release-state}"=="unreleased"]
+
+However, version {version} of {agent} has not yet been
+released, so no Docker image is currently available for this version.
+
+endif::[]
+
+
+[discrete]
+== Kubernetes deploy manifests
+
+With {fleet}, each agent enrols at a policy defined in {kib} and stored in
+{es}. The policy specifies how to collect observability data from the services
+to be monitored. The {agent} connects to a trusted {fleet-server} instance
+to retrieve the policy and report agent events.
+
+We recommend using {fleet} management because it makes the management and
+upgrade of agents considerably easier.
+
+On Kubernetes, deploy {agent} as a https://kubernetes.io/docs/concepts/workloads/controllers/daemonset/[DaemonSet]
+to ensure that there is a running instance on each node of the cluster.
+These instances are used to retrieve metrics from the host, such as system metrics, container stats,
+and metrics from all the services running on top of Kubernetes.
+
+In addition, one of the Pods in the DaemonSet will constantly hold a _leader lock_ which makes it responsible for
+handling cluster-wide monitoring.
+Find more information about leader election configuration options at <<kubernetes_leaderelection-provider, leader election provider>>.
+This instance is used to retrieve metrics that are unique for the whole
+cluster, such as Kubernetes events or
+https://github.com/kubernetes/kube-state-metrics[kube-state-metrics].
+
+
+Everything is deployed under the `kube-system` namespace by default. To change
+the namespace, modify the manifest file.
+
+To download the manifest file, run:
+
+["source", "sh", subs="attributes"]
+------------------------------------------------
+curl -L -O https://raw.githubusercontent.com/elastic/beats/{branch}/deploy/kubernetes/elastic-agent-managed-kubernetes.yaml
+------------------------------------------------
+
+[discrete]
+== Settings
+
+{agent} is enrolled to a running {fleet-server} using `FLEET_URL` parameter.
+The `FLEET_ENROLLMENT_TOKEN` parameter is used to connect {agent} to a
+specific {agent} policy.
+Learn more on how to get an enrollment token from {fleet} in the  {fleet-guide}/fleet-quick-start.html[Quick start
+guide].
+
+If `FLEET_ENROLLMENT_TOKEN` is empty then agent will connect to {kib} and get the default policy.
+In that case `KIBANA_HOST`, `KIBANA_FLEET_USERNAME`, `KIBANA_FLEET_PASSWORD` have to be specified.
+
+To specify different destination/credentials,
+change the following parameters in the manifest file:
+
+[source,yaml]
+------------------------------------------------
+- name: FLEET_URL
+  value: "https://fleet-server_url:port"
+- name: FLEET_ENROLLMENT_TOKEN
+  value: "token"
+- name: KIBANA_HOST
+  value: ""
+- name: KIBANA_FLEET_USERNAME
+  value: ""
+- name: KIBANA_FLEET_PASSWORD
+  value: ""
+------------------------------------------------
+
+// Begin collapsed section
+[%collapsible]
+.Configuration details
+====
+****
+
+[cols="2*<a"]
+|===
+| Settings | Description
+
+include::configuration/env/shared-env.asciidoc[tag=fleet-url]
+
+include::configuration/env/shared-env.asciidoc[tag=fleet-enrollment-token]
+
+include::configuration/env/shared-env.asciidoc[tag=kibana-host]
+
+include::configuration/env/shared-env.asciidoc[tag=kibana-fleet-username]
+
+include::configuration/env/shared-env.asciidoc[tag=kibana-fleet-password]
+|===
+
+See <<agent-environment-variables>> for all available options.
+
+****
+====
+
+[discrete]
+=== Run {agent} on master nodes
+
+Kubernetes master nodes can use https://kubernetes.io/docs/concepts/configuration/taint-and-toleration/[taints]
+to limit the workloads that can run on them. The manifest for managed {agent} defines
+tolerations to run on master nodes. Agents running on master nodes collect metrics from the control plane
+components (scheduler, controller manager) of Kuberentes.
+To disable {agent} from running on master nodes, remove the following part of the Daemonset spec:
+
+[source,yaml]
+------------------------------------------------
+spec:
+ tolerations:
+ - key: node-role.kubernetes.io/master
+   effect: NoSchedule
+------------------------------------------------
+
+
+[discrete]
+== Deploy
+
+If planing to deploy `state_*` datasets of Kubernetes package,
+https://github.com/kubernetes/kube-state-metrics#usage[kube-state-metrics] needs to be already deployed
+in the cluster. If `kube-state-metrics` is not already running, deploy it now (see the
+https://github.com/kubernetes/kube-state-metrics#kubernetes-deployment[Kubernetes
+deployment] docs).
+
+To deploy {agent} on Kubernetes, run:
+
+["source", "sh", subs="attributes"]
+------------------------------------------------
+kubectl create -f elastic-agent-managed-kubernetes.yaml
+------------------------------------------------
+
+To check the status, run:
+
+["source", "sh", subs="attributes"]
+------------------------------------------------
+$ kubectl get pod -n kube-system -l app=elastic-agent
+
+NAME                  READY   STATUS    RESTARTS   AGE
+elastic-agent-hrjbg   1/1     Running   0          12m
+elastic-agent-olpsd   1/1     Running   0          12m
+------------------------------------------------
+
+
+{agent}s should be enrolled to Fleet and user should be able to deploy Kubernetes package accordingly.
+This can be confirmed in {kib} under Fleet  / Agents section.

docs/en/ingest-management/elastic-agent/running-on-kubernetes-standalone.asciidoc

@@ -2,7 +2,7 @@
 [role="xpack"]
 = Run {agent} standalone on Kubernetes
 
-You can use {agent} https://www.docker.elastic.co/r/beats/elastic-agent[Docker images] on Kubernetes to
+Use {agent} https://www.docker.elastic.co/r/beats/elastic-agent[Docker images] on Kubernetes to
 retrieve cluster metrics.
 
 TIP: Running {ecloud} on Kubernetes? See {eck-ref}/k8s-elastic-agent.html[Run {elastic-agent} on ECK].
@@ -18,15 +18,15 @@ endif::[]
 == Kubernetes deploy manifests
 
 
-You deploy {agent} as a https://kubernetes.io/docs/concepts/workloads/controllers/daemonset/[DaemonSet]
-to ensure that there's a running instance on each node of the cluster. These
+Deploy {agent} as a https://kubernetes.io/docs/concepts/workloads/controllers/daemonset/[DaemonSet]
+to ensure that there is a running instance on each node of the cluster. These
 instances are used to retrieve most metrics from the host, such as system
 metrics, Docker stats, and metrics from all the services running on top of
 Kubernetes.
 
 In addition, one of the Pods in the DaemonSet will constantly hold a _leader lock_ which makes it responsible for
 handling cluster-wide monitoring.
-You can find more information about leader election configuration options at <<kubernetes_leaderelection-provider, leaderelection provider>>.
+Find more information about leader election configuration options at <<kubernetes_leaderelection-provider, leader election provider>>.
 This instance is used to retrieve metrics that are unique for the whole
 cluster, such as Kubernetes events or
 https://github.com/kubernetes/kube-state-metrics[kube-state-metrics]. If `kube-state-metrics` is not already
@@ -128,7 +128,7 @@ elastic-agent-hs4pb             1/1     Running   0          81m
 [discrete]
 == Autodiscover targeted Pods
 
-You can define autodiscover conditions to allow {agent} to automatically
+Autodiscover conditions can be defined to allow {agent} to automatically
 identify Pods and start collecting from them using predefined integrations. For example, if a
 user wants to automatically identify a Redis Pod and start monitoring it using the Redis integration,
 the following configuration should be added as an extra input in the Daemonset manifest: