[8.16](backport #42569) metricbeat: Update beat module with apm-serve…

…r tail sampling monitoring metrics fields (#42573)

* metricbeat: Update beat module with apm-server tail sampling monitoring metrics fields (#42569)

Update metricbeat beat module mapping to add back missing apm-server tail sampling montioring metrics fields.

The fields were missed in #40127

(cherry picked from commit 9134522)

# Conflicts:
#	metricbeat/module/beat/fields.go

* Fix conflicts

---------

Co-authored-by: Carson Ip <carsonip@users.noreply.github.com>
Co-authored-by: Carson Ip <carson.ip@elastic.co>

CHANGELOG.next.asciidoc

@@ -227,6 +227,7 @@ https://github.com/elastic/beats/compare/v8.8.1\...main[Check the HEAD diff]
 - Add new memory/cgroup metrics to Kibana module {pull}37232[37232]
 - Add SSL support to mysql module {pull}37997[37997]
 - Add SSL support for aerospike module {pull}38126[38126]
+- Update beat module with apm-server tail sampling monitoring metrics fields {pull}42569[42569]
 
 *Metricbeat*
 

metricbeat/docs/fields.asciidoc

@@ -7571,6 +7571,91 @@ alias to: beat.stats.apm_server.root.unset
 
 --
 
+
+
+*`beats_stats.apm-server.sampling.tail.dynamic_service_groups`*::
++
+--
+type: alias
+
+alias to: beat.stats.apm_server.sampling.tail.dynamic_service_groups
+
+--
+
+
+*`beats_stats.apm-server.sampling.tail.events.dropped`*::
++
+--
+type: alias
+
+alias to: beat.stats.apm_server.sampling.tail.events.dropped
+
+--
+
+*`beats_stats.apm-server.sampling.tail.events.failed_writes`*::
++
+--
+type: alias
+
+alias to: beat.stats.apm_server.sampling.tail.events.failed_writes
+
+--
+
+*`beats_stats.apm-server.sampling.tail.events.head_unsampled`*::
++
+--
+type: alias
+
+alias to: beat.stats.apm_server.sampling.tail.events.head_unsampled
+
+--
+
+*`beats_stats.apm-server.sampling.tail.events.processed`*::
++
+--
+type: alias
+
+alias to: beat.stats.apm_server.sampling.tail.events.processed
+
+--
+
+*`beats_stats.apm-server.sampling.tail.events.sampled`*::
++
+--
+type: alias
+
+alias to: beat.stats.apm_server.sampling.tail.events.sampled
+
+--
+
+*`beats_stats.apm-server.sampling.tail.events.stored`*::
++
+--
+type: alias
+
+alias to: beat.stats.apm_server.sampling.tail.events.stored
+
+--
+
+
+*`beats_stats.apm-server.sampling.tail.storage.lsm_size`*::
++
+--
+type: alias
+
+alias to: beat.stats.apm_server.sampling.tail.storage.lsm_size
+
+--
+
+*`beats_stats.apm-server.sampling.tail.storage.value_log_size`*::
++
+--
+type: alias
+
+alias to: beat.stats.apm_server.sampling.tail.storage.value_log_size
+
+--
+
 *`beats_stats.apm-server.sampling.transactions_dropped`*::
 +
 --
@@ -9661,6 +9746,73 @@ type: long
 
 --
 
+
+
+*`beat.stats.apm_server.sampling.tail.dynamic_service_groups`*::
++
+--
+type: long
+
+--
+
+
+*`beat.stats.apm_server.sampling.tail.events.dropped`*::
++
+--
+type: long
+
+--
+
+*`beat.stats.apm_server.sampling.tail.events.failed_writes`*::
++
+--
+type: long
+
+--
+
+*`beat.stats.apm_server.sampling.tail.events.head_unsampled`*::
++
+--
+type: long
+
+--
+
+*`beat.stats.apm_server.sampling.tail.events.processed`*::
++
+--
+type: long
+
+--
+
+*`beat.stats.apm_server.sampling.tail.events.sampled`*::
++
+--
+type: long
+
+--
+
+*`beat.stats.apm_server.sampling.tail.events.stored`*::
++
+--
+type: long
+
+--
+
+
+*`beat.stats.apm_server.sampling.tail.storage.lsm_size`*::
++
+--
+type: long
+
+--
+
+*`beat.stats.apm_server.sampling.tail.storage.value_log_size`*::
++
+--
+type: long
+
+--
+
 *`beat.stats.apm_server.sampling.transactions_dropped`*::
 +
 --

metricbeat/module/beat/_meta/fields.yml

@@ -477,9 +477,48 @@
                 - name: unset
                   type: alias
                   path: beat.stats.apm_server.root.unset
-            - name: sampling.transactions_dropped
-              type: alias
-              path: beat.stats.apm_server.sampling.transactions_dropped
+            - name: sampling
+              type: group
+              fields:
+                - name: tail
+                  type: group
+                  fields:
+                    - name: dynamic_service_groups
+                      type: alias
+                      path: beat.stats.apm_server.sampling.tail.dynamic_service_groups
+                    - name: events
+                      type: group
+                      fields:
+                        - name: dropped
+                          type: alias
+                          path: beat.stats.apm_server.sampling.tail.events.dropped
+                        - name: failed_writes
+                          type: alias
+                          path: beat.stats.apm_server.sampling.tail.events.failed_writes
+                        - name: head_unsampled
+                          type: alias
+                          path: beat.stats.apm_server.sampling.tail.events.head_unsampled
+                        - name: processed
+                          type: alias
+                          path: beat.stats.apm_server.sampling.tail.events.processed
+                        - name: sampled
+                          type: alias
+                          path: beat.stats.apm_server.sampling.tail.events.sampled
+                        - name: stored
+                          type: alias
+                          path: beat.stats.apm_server.sampling.tail.events.stored
+                    - name: storage
+                      type: group
+                      fields:
+                        - name: lsm_size
+                          type: alias
+                          path: beat.stats.apm_server.sampling.tail.storage.lsm_size
+                        - name: value_log_size
+                          type: alias
+                          path: beat.stats.apm_server.sampling.tail.storage.value_log_size
+                - name: transactions_dropped
+                  type: alias
+                  path: beat.stats.apm_server.sampling.transactions_dropped
             - name: server
               type: group
               fields:

metricbeat/module/beat/stats/_meta/fields.yml

@@ -358,8 +358,38 @@
                       type: long
             - name: unset
               type: long
-        - name: sampling.transactions_dropped
-          type: long
+        - name: sampling
+          type: group
+          fields:
+            - name: tail
+              type: group
+              fields:
+                - name: dynamic_service_groups
+                  type: long
+                - name: events
+                  type: group
+                  fields:
+                    - name: dropped
+                      type: long
+                    - name: failed_writes
+                      type: long
+                    - name: head_unsampled
+                      type: long
+                    - name: processed
+                      type: long
+                    - name: sampled
+                      type: long
+                    - name: stored
+                      type: long
+                - name: storage
+                  type: group
+                  fields:
+                    - name: lsm_size
+                      type: long
+                    - name: value_log_size
+                      type: long
+            - name: transactions_dropped
+              type: long
         - name: server
           type: group
           fields: