Fleet-managed agents: Add logging content (elastic#897)

* Add fleet-managed agent logging

* Review edits

elastic-agent/elastic-agent-logging.asciidoc

@@ -0,0 +1,85 @@
+[[elastic-agent-logging]]
+[role="xpack"]
+= Configure logging for Fleet-managed {agent}s
+
+Agent monitoring, which includes collecting agent logs and agent metrics,
+is enabled by default on each agent policy assigned to an agent. If
+logging for the agent is not required, you need to deselect the logging option when
+creating the agent policy.
+
+. In {kib}, go to *Management > {fleet}*.
+
+. Under the *Agent policies* tab, click *Create agent policy* > *Advanced options*.
+
+. Under *Agent monitoring*, deselect *Collect agent logs*.
+
+. To confirm your change, click *Save changes*.
+
+To disable logging on an agent policy already assigned to an agent:
+
+. Select the *Agents* tab, and then click the agent policy.
+
+. Click the *Settings* tab.
+
+. Under *Agent monitoring*, deselect *Collect agent logs*.
+
+. To confirm your change, click *Save changes*.
+
+[discrete]
+[[agent-view-log-events]]
+== View log events
+
+The *Logs* page for each agent enables you to monitor all of the log events flowing in
+from your agents and integrations in a centralized view.
+
+To help you get started with your analysis faster, you can use the search bar to create
+structured queries using {kibana-ref}/kuery-query.html[Kibana Query Language]. Along with
+the power of search, you also have the option to view historical logs from a
+specified time range.
+
+. In {kib}, go to *Management > {fleet}*.
+
+. Under *Agents*, click the agent name listed in the *Host* column.
+
+. Click the *Logs* tab.
+
+To view log events for an agent or related programs, such as {filebeat} or {fleet-server},
+make your selections under *Dataset*.
+
+[role="screenshot"]
+image::images/kibana-fleet-datasets.png[{fleet} showing datasets for logging]
+
+To view specific log levels relating to a log event, make your selections under *Log level*.
+You can select from `error`, `warn`, and `info`.
+
+[role="screenshot"]
+image::images/kibana-fleet-log-levels.png[Selector for logging levels]
+
+When you have searched and filtered your logs for a specific log event, you may want to
+examine the metadata and the structured fields associated with that event in the {logs-app}.
+Click *Open in Logs*.
+
+[discrete]
+[[agent-logging-levels]]
+== Set the agent logging level
+
+Within {fleet}, you can specify the logging level for each agent to help
+troubleshoot any issues.
+
+. In {kib}, go to *Management > {fleet}*.
+
+. Under *Agents*, select the agent from the *Host* column.
+
+. Click the *Logs* tab.
+
+. Located at the bottom of the Logs page, you can select the *Agent logging level*:
+
+* `error`: Logs errors and critical errors.
+* `warning`: Logs warnings, errors, and critical errors.
+* `info`: Logs informational messages, including the number of events that are published.
+Also logs any warnings, errors, or critical errors.
+* `debug`: Logs debug messages, including a detailed printout of all events flushed. Also
+logs informational messages, warnings, errors, and critical errors.
++
+. Once you have made your selection, click *Apply changes*.
+

elastic-agent/elastic-agent.asciidoc

@@ -23,6 +23,7 @@ To learn how to install, configure, and run your {agent}s, see:
 * <<elastic-agent-configuration>>
 * <<dynamic-input-configuration>>
 * <<agent-environment-variables>>
+* <<elastic-agent-logging>>
 * <<elastic-agent-standalone-logging-config>>
 
 include::install-elastic-agent.asciidoc[leveloffset=+1]
@@ -53,6 +54,8 @@ include::elastic-agent-capabilities.asciidoc[leveloffset=+1]
 
 include::configuration/env/container-envs.asciidoc[leveloffset=+1]
 
+include::elastic-agent-logging.asciidoc[leveloffset=+1]
+
 include::elastic-agent-standalone-logging.asciidoc[leveloffset=+1]
 
 include::redirects.asciidoc[leveloffset=+1]