Update variable names and readme to new style

Author: grubernaut

plugins/inputs/mongodb/README.md

@@ -69,6 +69,7 @@ Error in input [mongodb]: not authorized on admin to execute command { serverSta
     - repl_lag (integer)
     - repl_queries_per_sec (integer)
     - repl_updates_per_sec (integer)
+    - repl_oplog_window_sec (integer)
     - resident_megabytes (integer)
     - state (string)
     - total_available (integer)
@@ -92,35 +93,6 @@ Error in input [mongodb]: not authorized on admin to execute command { serverSta
     - wtcache_tracked_dirty_bytes (integer)
     - wtcache_worker_thread_evictingpages (integer)
 
-The telegraf plugin collects mongodb stats exposed by serverStatus and few more
-and create a single measurement containing values e.g.
- * active_reads
- * active_writes
- * commands_per_sec
- * deletes_per_sec
- * flushes_per_sec
- * getmores_per_sec
- * inserts_per_sec
- * net_in_bytes
- * net_out_bytes
- * open_connections
- * percent_cache_dirty
- * percent_cache_used
- * queries_per_sec
- * queued_reads
- * queued_writes
- * resident_megabytes
- * updates_per_sec
- * vsize_megabytes
- * total_in_use
- * total_available
- * total_created
- * total_refreshing
- * ttl_deletes_per_sec
- * ttl_passes_per_sec
- * repl_lag
- * repl_oplog_window_s
- * jumbo_chunks (only if mongos or mongo config)
 - mongodb_db_stats
   - tags:
     - db_name
@@ -137,27 +109,18 @@ and create a single measurement containing values e.g.
     - storage_size (integer)
     - type (string)
 
-If gather_db_stats is set to true, it will also collect per database stats exposed by db.stats()
-creating another measurement called mongodb_db_stats and containing values:
- * collections
- * objects
- * avg_obj_size
- * data_size
- * storage_size
- * num_extents
- * indexes
- * index_size
- * ok
-
-If multiple shard hosts are found via the `shardConnPoolStats` command, it will also collect per-host shard stats exposed
-by `shardConnPoolStats` creating another measurement called `mongodb_shard_host_stats`, containing the following values:
- * in_use
- * available
- * created
- * refreshing
+- mongodb_shard_stats
+  - tags:
+    - hostname
+  - fields:
+    - in_use (integer)
+    - available (integer)
+    - created (integer)
+    - refreshing (integer)
 
 ### Example Output:
 ```
 mongodb,hostname=127.0.0.1:27017 active_reads=0i,active_writes=0i,commands_per_sec=6i,deletes_per_sec=0i,flushes_per_sec=0i,getmores_per_sec=1i,inserts_per_sec=0i,jumbo_chunks=0i,member_status="PRI",net_in_bytes=851i,net_out_bytes=23904i,open_connections=6i,percent_cache_dirty=0,percent_cache_used=0,queries_per_sec=2i,queued_reads=0i,queued_writes=0i,repl_commands_per_sec=0i,repl_deletes_per_sec=0i,repl_getmores_per_sec=0i,repl_inserts_per_sec=0i,repl_lag=0i,repl_queries_per_sec=0i,repl_updates_per_sec=0i,resident_megabytes=67i,state="PRIMARY",total_available=0i,total_created=0i,total_in_use=0i,total_refreshing=0i,ttl_deletes_per_sec=0i,ttl_passes_per_sec=0i,updates_per_sec=0i,vsize_megabytes=729i,wtcache_app_threads_page_read_count=4i,wtcache_app_threads_page_read_time=18i,wtcache_app_threads_page_write_count=6i,wtcache_bytes_read_into=10075i,wtcache_bytes_written_from=115711i,wtcache_current_bytes=86038i,wtcache_max_bytes_configured=1073741824i,wtcache_pages_evicted_by_app_thread=0i,wtcache_pages_queued_for_eviction=0i,wtcache_server_evicting_pages=0i,wtcache_tracked_dirty_bytes=0i,wtcache_worker_thread_evictingpages=0i 1522798796000000000
 mongodb_db_stats,db_name=local,hostname=127.0.0.1:27017 avg_obj_size=818.625,collections=5i,data_size=6549i,index_size=86016i,indexes=4i,num_extents=0i,objects=8i,ok=1i,storage_size=118784i,type="db_stat" 1522799074000000000
+mongodb_shard_stats,hostname=127.0.0.1:27017,in_use=3i,available=3i,created=4i,refreshing=0i 1522799074000000000
 ```

plugins/inputs/mongodb/mongodb_data.go

@@ -204,9 +204,9 @@ func (d *MongodbData) flush(acc telegraf.Accumulator) {
 		db.Fields = make(map[string]interface{})
 	}
 	for _, host := range d.ShardHostData {
-		d.Tags["shard_host_name"] = host.Name
+		d.Tags["hostname"] = host.Name
 		acc.AddFields(
-			"mongodb_shard_host_stats",
+			"mongodb_shard_stats",
 			host.Fields,
 			d.Tags,
 			d.StatLine.Time,

plugins/inputs/mongodb/mongodb_data_test.go

@@ -146,10 +146,10 @@ func TestAddShardHostStats(t *testing.T) {
 	var hostsFound []string
 	for host, _ := range hostStatLines {
 		for key, _ := range ShardHostStats {
-			assert.True(t, acc.HasInt64Field("mongodb_shard_host_stats", key))
+			assert.True(t, acc.HasInt64Field("mongodb_shard_stats", key))
 		}
 
-		assert.True(t, acc.HasTag("mongodb_shard_host_stats", "shard_host_name"))
+		assert.True(t, acc.HasTag("mongodb_shard_stats", "hostname"))
 		hostsFound = append(hostsFound, host)
 	}