Updated documentation based on review comments from @sparrc

CHANGELOG.md

@@ -1,6 +1,7 @@
 ## v0.12.1 [unreleased]
 
 ### Features
+- [#952](https://github.com/influxdata/telegraf/pull/952): Cassandra input plugin. Thanks @subhachandrachandra!
 - [#976](https://github.com/influxdata/telegraf/pull/976): Reduce allocations in the UDP and statsd inputs.
 - [#979](https://github.com/influxdata/telegraf/pull/979): Reduce allocations in the TCP listener.
 - [#935](https://github.com/influxdata/telegraf/pull/935): AWS Cloudwatch input plugin. Thanks @joshhardy & @ljosa!

README.md

@@ -160,6 +160,7 @@ Currently implemented sources:
 * [aerospike](https://github.com/influxdata/telegraf/tree/master/plugins/inputs/aerospike)
 * [apache](https://github.com/influxdata/telegraf/tree/master/plugins/inputs/apache)
 * [bcache](https://github.com/influxdata/telegraf/tree/master/plugins/inputs/bcache)
+* [cassandra](https://github.com/influxdata/telegraf/tree/master/plugins/inputs/cassandra)
 * [couchbase](https://github.com/influxdata/telegraf/tree/master/plugins/inputs/couchbase)
 * [couchdb](https://github.com/influxdata/telegraf/tree/master/plugins/inputs/couchdb)
 * [disque](https://github.com/influxdata/telegraf/tree/master/plugins/inputs/disque)

plugins/inputs/cassandra/README.md

@@ -9,15 +9,15 @@
 
 The Cassandra plugin collects Cassandra/JVM metrics exposed as MBean's attributes through jolokia REST endpoint. All metrics are collected for each server configured.
 
-See: https://jolokia.org/
+See: https://jolokia.org/ and [Cassandra Documentation](http://docs.datastax.com/en/cassandra/3.x/cassandra/operations/monitoringCassandraTOC.html)
 
 # Measurements:
 Cassandra plugin produces one or more measurements for each metric configured, adding Server's name  as `host` tag. More than one measurement is generated when querying table metrics with a wildcard for the keyspace or table name.
 
 Given a configuration like:
 
-```ini
+```toml
-[inputs.cassandra]
+[[inputs.cassandra]]
   context = "/jolokia/read"
   servers = [":8778"]
   metrics = ["/java.lang:type=Memory/HeapMemoryUsage"]
@@ -28,3 +28,98 @@ The collected metrics will be:
 ```
 javaMemory,host=myHost,mname=HeapMemoryUsage HeapMemoryUsage_committed=1040187392,HeapMemoryUsage_init=1050673152,HeapMemoryUsage_max=1040187392,HeapMemoryUsage_used=368155000 1459551767230567084
 ```
+
+# Useful Metrics:
+
+Here is a list of metrics that might be useful to monitor your cassandra cluster. This was put together from multiple sources on the web.
+
+- [How to monitor Cassandra performance metrics](https://www.datadoghq.com/blog/how-to-monitor-cassandra-performance-metrics)
+- [Cassandra Documentation](http://docs.datastax.com/en/cassandra/3.x/cassandra/operations/monitoringCassandraTOC.html)
+
+####measurement = javaGarbageCollector
+
+- /java.lang:type=GarbageCollector,name=ConcurrentMarkSweep/CollectionTime       
+- /java.lang:type=GarbageCollector,name=ConcurrentMarkSweep/CollectionCount
+- /java.lang:type=GarbageCollector,name=ParNew/CollectionTime          
+- /java.lang:type=GarbageCollector,name=ParNew/CollectionCount
+
+####measurement = javaMemory
+
+- /java.lang:type=Memory/HeapMemoryUsage
+- /java.lang:type=Memory/NonHeapMemoryUsage
+
+####measurement = cassandraCache
+
+- /org.apache.cassandra.metrics:type=Cache,scope=KeyCache,name=Hit
+- /org.apache.cassandra.metrics:type=Cache,scope=KeyCache,name=Requests
+- /org.apache.cassandra.metrics:type=Cache,scope=KeyCache,name=Entries
+- /org.apache.cassandra.metrics:type=Cache,scope=KeyCache,name=Size 
+- /org.apache.cassandra.metrics:type=Cache,scope=KeyCache,name=Capacity 
+- /org.apache.cassandra.metrics:type=Cache,scope=RowCache,name=Hit
+- /org.apache.cassandra.metrics:type=Cache,scope=RowCache,name=Requests     
+- /org.apache.cassandra.metrics:type=Cache,scope=RowCache,name=Entries
+- /org.apache.cassandra.metrics:type=Cache,scope=RowCache,name=Size
+- /org.apache.cassandra.metrics:type=Cache,scope=RowCache,name=Capacity
+
+####measurement = cassandraClient
+
+- /org.apache.cassandra.metrics:type=Client,name=connectedNativeClients
+
+####measurement = cassandraClientRequest
+
+- /org.apache.cassandra.metrics:type=ClientRequest,scope=Read,name=TotalLatency        
+- /org.apache.cassandra.metrics:type=ClientRequest,scope=Write,name=TotalLatency         
+- /org.apache.cassandra.metrics:type=ClientRequest,scope=Read,name=Latency       
+- /org.apache.cassandra.metrics:type=ClientRequest,scope=Write,name=Latency        
+- /org.apache.cassandra.metrics:type=ClientRequest,scope=Read,name=Timeouts       
+- /org.apache.cassandra.metrics:type=ClientRequest,scope=Write,name=Timeouts
+- /org.apache.cassandra.metrics:type=ClientRequest,scope=Read,name=Unavailables        
+- /org.apache.cassandra.metrics:type=ClientRequest,scope=Write,name=Unavailables         
+- /org.apache.cassandra.metrics:type=ClientRequest,scope=Read,name=Failures         
+- /org.apache.cassandra.metrics:type=ClientRequest,scope=Write,name=Failures 
+
+####measurement = cassandraCommitLog
+
+- /org.apache.cassandra.metrics:type=CommitLog,name=PendingTasks        
+- /org.apache.cassandra.metrics:type=CommitLog,name=TotalCommitLogSize
+
+####measurement = cassandraCompaction
+
+- /org.apache.cassandra.metrics:type=Compaction,name=CompletedTask
+- /org.apache.cassandra.metrics:type=Compaction,name=PendingTasks    
+- /org.apache.cassandra.metrics:type=Compaction,name=TotalCompactionsCompleted
+- /org.apache.cassandra.metrics:type=Compaction,name=BytesCompacted
+
+####measurement = cassandraStorage
+
+- /org.apache.cassandra.metrics:type=Storage,name=Load
+-  /org.apache.cassandra.metrics:type=Storage,name=Exceptions 
+
+####measurement = cassandraTable
+Using wildcards for "keyspace" and "scope" can create a lot of series as metrics will be reported for every table and keyspace including internal system tables. Specify a keyspace name and/or a table name to limit them.
+
+- /org.apache.cassandra.metrics:type=Table,keyspace=*,scope=*,name=LiveDiskSpaceUsed
+- /org.apache.cassandra.metrics:type=Table,keyspace=*,scope=*,name=TotalDiskSpaceUsed
+- /org.apache.cassandra.metrics:type=Table,keyspace=*,scope=*,name=ReadLatency
+- /org.apache.cassandra.metrics:type=Table,keyspace=*,scope=*,name=CoordinatorReadLatency 
+- /org.apache.cassandra.metrics:type=Table,keyspace=*,scope=*,name=WriteLatency 
+- /org.apache.cassandra.metrics:type=Table,keyspace=*,scope=*,name=ReadTotalLatency 
+- /org.apache.cassandra.metrics:type=Table,keyspace=*,scope=*,name=WriteTotalLatency              
+
+
+####measurement = cassandraThreadPools
+
+- /org.apache.cassandra.metrics:type=ThreadPools,path=internal,scope=CompactionExecutor,name=ActiveTasks          
+- /org.apache.cassandra.metrics:type=ThreadPools,path=internal,scope=AntiEntropyStage,name=ActiveTasks         
+-  /org.apache.cassandra.metrics:type=ThreadPools,path=request,scope=CounterMutationStage,name=PendingTasks
+- /org.apache.cassandra.metrics:type=ThreadPools,path=request,scope=CounterMutationStage,name=CurrentlyBlockedTasks        
+- /org.apache.cassandra.metrics:type=ThreadPools,path=request,scope=MutationStage,name=PendingTasks
+- /org.apache.cassandra.metrics:type=ThreadPools,path=request,scope=MutationStage,name=CurrentlyBlockedTasks        
+- /org.apache.cassandra.metrics:type=ThreadPools,path=request,scope=ReadRepairStage,name=PendingTasks
+- /org.apache.cassandra.metrics:type=ThreadPools,path=request,scope=ReadRepairStage,name=CurrentlyBlockedTasks        
+- /org.apache.cassandra.metrics:type=ThreadPools,path=request,scope=ReadStage,name=PendingTasks
+- /org.apache.cassandra.metrics:type=ThreadPools,path=request,scope=ReadStage,name=CurrentlyBlockedTasks          
+-  /org.apache.cassandra.metrics:type=ThreadPools,path=request,scope=RequestResponseStage,name=PendingTasks                  
+- /org.apache.cassandra.metrics:type=ThreadPools,path=request,scope=RequestResponseStage,name=CurrentlyBlockedTasks 
+
+

plugins/inputs/cassandra/cassandra.go

@@ -196,8 +196,10 @@ func (j *Cassandra) SampleConfig() string {
   ## ReadLatency metrics for all keyspaces and tables.
   ## "type=Table" in the query works with Cassandra3.0. Older versions might
   ## need to use "type=ColumnFamily"
-  metrics  = ["/java.lang:type=Memory/HeapMemoryUsage",
+  metrics  = [
-              "/org.apache.cassandra.metrics:type=Table,keyspace=*,scope=*,name=ReadLatency"]
+    "/java.lang:type=Memory/HeapMemoryUsage",
+    "/org.apache.cassandra.metrics:type=Table,keyspace=*,scope=*,name=ReadLatency"
+  ]
 `
 }