Add warning about setup.template.overwrite to documentation and refer…

…ence configuration (elastic#22357)

## What does this PR do?

This PR adds a warning about `setup.template.overwrite` option.

## Why is it important?

Users might enable this option and then start multiple instances of Beats at the same time. This can overload Elasticsearch with too many template update requests.

auditbeat/auditbeat.reference.yml

@@ -1177,6 +1177,8 @@ output.elasticsearch:
 #setup.template.json.name: ""
 
 # Overwrite existing template
+# Do not enable this option for more than one instance of auditbeat as it might
+# overload your Elasticsearch with too many update requests.
 #setup.template.overwrite: false
 
 # Elasticsearch template settings

filebeat/filebeat.reference.yml

@@ -2043,6 +2043,8 @@ output.elasticsearch:
 #setup.template.json.name: ""
 
 # Overwrite existing template
+# Do not enable this option for more than one instance of filebeat as it might
+# overload your Elasticsearch with too many update requests.
 #setup.template.overwrite: false
 
 # Elasticsearch template settings

heartbeat/heartbeat.reference.yml

@@ -1354,6 +1354,8 @@ output.elasticsearch:
 #setup.template.json.name: ""
 
 # Overwrite existing template
+# Do not enable this option for more than one instance of heartbeat as it might
+# overload your Elasticsearch with too many update requests.
 #setup.template.overwrite: false
 
 # Elasticsearch template settings

journalbeat/journalbeat.reference.yml

@@ -1119,6 +1119,8 @@ output.elasticsearch:
 #setup.template.json.name: ""
 
 # Overwrite existing template
+# Do not enable this option for more than one instance of journalbeat as it might
+# overload your Elasticsearch with too many update requests.
 #setup.template.overwrite: false
 
 # Elasticsearch template settings

libbeat/_meta/config/setup.template.reference.yml.tmpl

@@ -40,6 +40,8 @@
 #setup.template.json.name: ""
 
 # Overwrite existing template
+# Do not enable this option for more than one instance of {{.BeatName}} as it might
+# overload your Elasticsearch with too many update requests.
 #setup.template.overwrite: false
 
 # Elasticsearch template settings

libbeat/docs/howto/load-index-templates.asciidoc

@@ -48,6 +48,10 @@ If the template already exists, it’s not overwritten unless you configure
 [[overwrite-template]]
 === Overwrite an existing index template
 
+WARNING: Do not enable this option for more than one instance of {beatname_uc}. If you start
+multiple instances at the same time, it can overload your {es} with too many
+template update requests.
+
 To overwrite a template that's already loaded into {es}, set:
 
 [source,yaml]

libbeat/docs/template-config.asciidoc

@@ -60,7 +60,8 @@ relative path is set, it is considered relative to the config path. See the <<di
 section for details.
 
 *`setup.template.overwrite`*:: A boolean that specifies whether to overwrite the existing template. The default
-is false.
+is false. Do not enable this option is you start more than one instance of {beatname_uc} at the same time. It
+can overload your {es} by sending too many template update reqests.
 
 *`setup.template.settings`*:: A dictionary of settings to place into the `settings.index` dictionary of the
 Elasticsearch template. For more details about the available Elasticsearch mapping options, please

metricbeat/metricbeat.reference.yml

@@ -1945,6 +1945,8 @@ output.elasticsearch:
 #setup.template.json.name: ""
 
 # Overwrite existing template
+# Do not enable this option for more than one instance of metricbeat as it might
+# overload your Elasticsearch with too many update requests.
 #setup.template.overwrite: false
 
 # Elasticsearch template settings

packetbeat/packetbeat.reference.yml

@@ -1616,6 +1616,8 @@ output.elasticsearch:
 #setup.template.json.name: ""
 
 # Overwrite existing template
+# Do not enable this option for more than one instance of packetbeat as it might
+# overload your Elasticsearch with too many update requests.
 #setup.template.overwrite: false
 
 # Elasticsearch template settings

winlogbeat/winlogbeat.reference.yml

@@ -1099,6 +1099,8 @@ output.elasticsearch:
 #setup.template.json.name: ""
 
 # Overwrite existing template
+# Do not enable this option for more than one instance of winlogbeat as it might
+# overload your Elasticsearch with too many update requests.
 #setup.template.overwrite: false
 
 # Elasticsearch template settings

x-pack/auditbeat/auditbeat.reference.yml

@@ -1233,6 +1233,8 @@ output.elasticsearch:
 #setup.template.json.name: ""
 
 # Overwrite existing template
+# Do not enable this option for more than one instance of auditbeat as it might
+# overload your Elasticsearch with too many update requests.
 #setup.template.overwrite: false
 
 # Elasticsearch template settings

x-pack/filebeat/filebeat.reference.yml

@@ -3555,6 +3555,8 @@ output.elasticsearch:
 #setup.template.json.name: ""
 
 # Overwrite existing template
+# Do not enable this option for more than one instance of filebeat as it might
+# overload your Elasticsearch with too many update requests.
 #setup.template.overwrite: false
 
 # Elasticsearch template settings

x-pack/functionbeat/functionbeat.reference.yml

@@ -1084,6 +1084,8 @@ output.elasticsearch:
 #setup.template.json.name: ""
 
 # Overwrite existing template
+# Do not enable this option for more than one instance of functionbeat as it might
+# overload your Elasticsearch with too many update requests.
 #setup.template.overwrite: false
 
 # Elasticsearch template settings

x-pack/heartbeat/heartbeat.reference.yml

@@ -1354,6 +1354,8 @@ output.elasticsearch:
 #setup.template.json.name: ""
 
 # Overwrite existing template
+# Do not enable this option for more than one instance of heartbeat as it might
+# overload your Elasticsearch with too many update requests.
 #setup.template.overwrite: false
 
 # Elasticsearch template settings

x-pack/metricbeat/metricbeat.reference.yml

@@ -2440,6 +2440,8 @@ output.elasticsearch:
 #setup.template.json.name: ""
 
 # Overwrite existing template
+# Do not enable this option for more than one instance of metricbeat as it might
+# overload your Elasticsearch with too many update requests.
 #setup.template.overwrite: false
 
 # Elasticsearch template settings

x-pack/packetbeat/packetbeat.reference.yml

@@ -1616,6 +1616,8 @@ output.elasticsearch:
 #setup.template.json.name: ""
 
 # Overwrite existing template
+# Do not enable this option for more than one instance of packetbeat as it might
+# overload your Elasticsearch with too many update requests.
 #setup.template.overwrite: false
 
 # Elasticsearch template settings

x-pack/winlogbeat/winlogbeat.reference.yml

@@ -1142,6 +1142,8 @@ output.elasticsearch:
 #setup.template.json.name: ""
 
 # Overwrite existing template
+# Do not enable this option for more than one instance of winlogbeat as it might
+# overload your Elasticsearch with too many update requests.
 #setup.template.overwrite: false
 
 # Elasticsearch template settings