Metricbeat: Add memcached used bytes metrics (elastic#7740)

(cherry picked from commit 60e8999)

CHANGELOG.asciidoc

@@ -471,6 +471,35 @@ https://github.com/elastic/beats/compare/v6.2.3...v6.3.0[View commits]
 - Release config reloading feature as GA. {pull}6891[6891]
 - Kubernetes deployment: Add ServiceAccount config to system metricbeat. {pull}6824[6824]
 - Kubernetes deployment: Add DNS Policy to system metricbeat. {pull}6656[6656]
+- Add experimental Elasticsearch index metricset. {pull}6881[6881]
+- Add dashboards and visualizations for haproxy metrics. {pull}6934[6934]
+- Add Jolokia agent in proxy mode. {pull}6475[6475]
+- Add message rates to the RabbitMQ queue metricset {issue}6442[6442] {pull}6606[6606]
+- Add exchanges metricset to the RabbitMQ module {issue}6442[6442] {pull}6607[6607]
+- Add Elasticsearch index_summary metricset. {pull}6918[6918]
+- Add config option `management_path_prefix` for RabbitMQ module to configure management plugin path prefix {issue}6875[6875] {pull}7074[7074]
+- Add shard metricset to Elasticsearch module. {pull}7006[7006]
+- Add apiserver metricset to Kubernetes module. {pull}7059[7059]
+- Add maxmemory to redis info metricset. {pull}7127[7127]
+- Set guest as default user in RabbitMQ module. {pull}7107[7107]
+- Add postgresql statement metricset. {issue}7048[7048] {pull}7060[7060]
+- Update `state_container` metricset to support latest `kube-state-metrics` version. {pull}7216[7216]
+- Collect accumulated docker network metrics and mark old ones as deprecated. {pull}7253[7253]
+- Add TLS support to MongoDB module. {pull}7401[7401]
+- Added Traefik module with health metricset. {pull}7413[7413]
+- Add Elasticsearch ml_job metricsets. {pull}7196[7196]
+- Add support for bearer token files to HTTP helper. {pull}7527[7527]
+- Add Elasticsearch index recovery metricset. {pull}7225[7225]
+- Add `locks`, `global_locks`, `oplatencies` and `process` fields to `status` metricset of MongoDB module. {pull}7613[7613]
+- Run Kafka integration tests on version 1.1.0 {pull}7616[7616]
+- Release raid and socket metricset from system module as GA. {pull}7658[7658]
+- Release elasticsearch module and all its metricsets as beta. {pull}7662[7662]
+- Release munin and traefik module as beta. {pull}7660[7660]
+- Add envoyproxy module. {pull}7569[7569]
+- Release prometheus collector metricset as GA. {pull}7660[7660]
+- Add Elasticsearch `cluster_stats` metricset. {pull}7638[7638]
+- Added `basepath` setting for HTTP-based metricsets {pull}7700[7700]
+- Add metrics about cache size to memcached module {pull}7740[7740]
 
 *Packetbeat*
 

metricbeat/docs/fields.asciidoc

@@ -9684,6 +9684,26 @@ type: long
 Number of objects removed from the cache to free up memory for new items because Memcached reached it's maximum memory setting (limit_maxbytes).
 
 
+--
+
+*`memcached.stats.bytes.current`*::
++
+--
+type: long
+
+Number of bytes currently used for caching items.
+
+
+--
+
+*`memcached.stats.bytes.limit`*::
++
+--
+type: long
+
+Number of bytes this server is allowed to use for storage.
+
+
 --
 
 [[exported-fields-mongodb]]

metricbeat/module/memcached/stats/_meta/data.json

@@ -6,6 +6,10 @@
     },
     "memcached": {
         "stats": {
+            "bytes": {
+                "current": 0,
+                "limit": 67108864
+            },
             "cmd": {
                 "get": 0,
                 "set": 0
@@ -42,4 +46,4 @@
         "name": "stats",
         "rtt": 115
     }
-}
+}

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

@@ -83,3 +83,15 @@
       description: >
         Number of objects removed from the cache to free up memory for new items
         because Memcached reached it's maximum memory setting (limit_maxbytes).
+
+    - name: bytes.current
+      type: long
+      formate: bytes
+      description: >
+        Number of bytes currently used for caching items.
+
+    - name: bytes.limit
+      type: long
+      formate: bytes
+      description: >
+        Number of bytes this server is allowed to use for storage.

metricbeat/module/memcached/stats/data.go

@@ -52,5 +52,9 @@ var (
 			"total":   c.Int("total_items"),
 		},
 		"evictions": c.Int("evictions"),
+		"bytes": s.Object{
+			"current": c.Int("bytes"),
+			"limit":   c.Int("limit_maxbytes"),
+		},
 	}
 )