The Site-to-Site Metrics Reporting Task allows the user to publish NiFi's metrics (as in the Ambari reporting task) to the same NiFi instance or another NiFi instance. This provides a great deal of power because it allows the user to make use of all of the different Processors that are available in NiFi in order to process or distribute that data.

## Ambari format

There are two available output formats. The first one is the Ambari format as defined in the Ambari Metrics Collector API which is a JSON with dynamic keys. If using this format you might be interested by the below Jolt specification to transform the data.

    			[
    			  {
    			    "operation": "shift",
    			    "spec": {
    			      "metrics": {
    			        "*": {
    			          "metrics": {
    			            "*": {
    			              "$": "metrics.[#4].metrics.time",
    			              "@": "metrics.[#4].metrics.value"
    			            }
    			          },
    			          "*": "metrics.[&1].&"
    			        }
    			      }
    			    }
    			  }
    			]

This would transform the below sample:

    			{
    				"metrics": [{
    					"metricname": "jvm.gc.time.G1OldGeneration",
    					"appid": "nifi",
    					"instanceid": "8927f4c0-0160-1000-597a-ea764ccd81a7",
    					"hostname": "localhost",
    					"timestamp": "1520456854361",
    					"starttime": "1520456854361",
    					"metrics": {
    						"1520456854361": "0"
    					}
    				}, {
    					"metricname": "jvm.thread_states.terminated",
    					"appid": "nifi",
    					"instanceid": "8927f4c0-0160-1000-597a-ea764ccd81a7",
    					"hostname": "localhost",
    					"timestamp": "1520456854361",
    					"starttime": "1520456854361",
    					"metrics": {
    						"1520456854361": "0"
    					}
    				}]
    			}

into:

    			{
    				"metrics": [{
    					"metricname": "jvm.gc.time.G1OldGeneration",
    					"appid": "nifi",
    					"instanceid": "8927f4c0-0160-1000-597a-ea764ccd81a7",
    					"hostname": "localhost",
    					"timestamp": "1520456854361",
    					"starttime": "1520456854361",
    					"metrics": {
    						"time": "1520456854361",
    						"value": "0"
    					}
    				}, {
    					"metricname": "jvm.thread_states.terminated",
    					"appid": "nifi",
    					"instanceid": "8927f4c0-0160-1000-597a-ea764ccd81a7",
    					"hostname": "localhost",
    					"timestamp": "1520456854361",
    					"starttime": "1520456854361",
    					"metrics": {
    						"time": "1520456854361",
    						"value": "0"
    					}
    				}]
    			}

## Record format

The second format is leveraging the record framework of NiFi so that the user can define a Record Writer and directly specify the output format and data with the assumption that the input schema is the following:

    			{
    			  "type" : "record",
    			  "name" : "metrics",
    			  "namespace" : "metrics",
    			  "fields" : [
    				{ "name" : "appid", "type" : "string" },
    				{ "name" : "instanceid", "type" : "string" },
    				{ "name" : "hostname", "type" : "string" },
    				{ "name" : "timestamp", "type" : "long" },
    				{ "name" : "loadAverage1min", "type" : "double" },
    				{ "name" : "availableCores", "type" : "int" },
    				{ "name" : "FlowFilesReceivedLast5Minutes", "type" : "int" },
    				{ "name" : "BytesReceivedLast5Minutes", "type" : "long" },
    				{ "name" : "FlowFilesSentLast5Minutes", "type" : "int" },
    				{ "name" : "BytesSentLast5Minutes", "type" : "long" },
    				{ "name" : "FlowFilesQueued", "type" : "int" },
    				{ "name" : "BytesQueued", "type" : "long" },
    				{ "name" : "BytesReadLast5Minutes", "type" : "long" },
    				{ "name" : "BytesWrittenLast5Minutes", "type" : "long" },
    				{ "name" : "ActiveThreads", "type" : "int" },
    				{ "name" : "TotalTaskDurationSeconds", "type" : "long" },
    				{ "name" : "TotalTaskDurationNanoSeconds", "type" : "long" },
    				{ "name" : "jvmuptime", "type" : "long" },
    				{ "name" : "jvmheap_used", "type" : "double" },
    				{ "name" : "jvmheap_usage", "type" : "double" },
    				{ "name" : "jvmnon_heap_usage", "type" : "double" },
    				{ "name" : "jvmthread_statesrunnable", "type" : ["int", "null"] },
    				{ "name" : "jvmthread_statesblocked", "type" : ["int", "null"] },
    				{ "name" : "jvmthread_statestimed_waiting", "type" : ["int", "null"] },
    				{ "name" : "jvmthread_statesterminated", "type" : ["int", "null"] },
    				{ "name" : "jvmthread_count", "type" : "int" },
    				{ "name" : "jvmdaemon_thread_count", "type" : "int" },
    				{ "name" : "jvmfile_descriptor_usage", "type" : "double" },
    				{ "name" : "jvmgcruns", "type" : ["long", "null"] },
    				{ "name" : "jvmgctime", "type" : ["long", "null"] }
    			  ]
    			}