Data format output documentation

DATA_FORMATS_OUTPUT.md

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+# Telegraf Output Data Formats
+
+Telegraf metrics, like InfluxDB
+[points](https://docs.influxdata.com/influxdb/v0.10/write_protocols/line/),
+are a combination of four basic parts:
+
+1. Measurement Name
+1. Tags
+1. Fields
+1. Timestamp
+
+In InfluxDB line protocol, these 4 parts are easily defined in textual form:
+`measurement_name[,tag1=val1,...] field1=val1[,field2=val2,...] [timestamp]`
+
+For Telegraf outputs that write textual data (such as `kafka`, `mqtt`, and `file`),
+InfluxDB line protocol was originally the only available output format. But now
+we are normalizing telegraf metric "serializers" into a plugin-like format across
+all output plugins that can support it. You will be able to identify a plugin
+that supports different data formats by the presence of a `data_format`
+config option, for example, in the file plugin:
+
+```toml
+[[outputs.file]]
+  ### Files to write to, "stdout" is a specially handled file.
+  files = ["stdout", "/tmp/metrics.out"]
+
+  ### Data format to output. This can be "influx" or "graphite"
+  ### Each data format has it's own unique set of configuration options, read
+  ### more about them here:
+  ### https://github.com/influxdata/telegraf/blob/master/DATA_FORMATS_OUTPUT.md
+  data_format = "influx"
+
+  ### Additional configuration options go here
+```
+
+Each data_format has an additional set of configuration options available, which
+I'll go over below.
+
+## Influx:
+
+There are no additional configuration options for InfluxDB line-protocol. The
+metrics are parsed directly into Telegraf metrics.
+
+#### Influx Configuration:
+
+```toml
+[[outputs.file]]
+  ### Files to write to, "stdout" is a specially handled file.
+  files = ["stdout", "/tmp/metrics.out"]
+
+  ### Data format to output. This can be "influx" or "graphite"
+  ### Each data format has it's own unique set of configuration options, read
+  ### more about them here:
+  ### https://github.com/influxdata/telegraf/blob/master/DATA_FORMATS_OUTPUT.md
+  data_format = "influx"
+
+  ### Additional configuration options go here
+```
+
+## Graphite:
+
+The Graphite data format translates Telegraf metrics into _dot_ buckets.
+The format is:
+
+```
+[prefix].[host tag].[all tags (alphabetical)].[measurement name].[field name] value timestamp
+```
+
+Which means the following influx metric -> graphite conversion would happen:
+
+```
+cpu,cpu=cpu-total,dc=us-east-1,host=tars usage_idle=98.08869456589632,usage_user=0.886945658963148 1455320660004257758
+=>
+tars.cpu-total.us-east-1.cpu.usage_user 0.5620784411691232 1455320690
+tars.cpu-total.us-east-1.cpu.usage_idle 98.5885585810642 1455320690
+```
+
+`prefix` is a configuration option when using the graphite output data format.
+
+#### Graphite Configuration:
+
+```toml
+[[outputs.file]]
+  ### Files to write to, "stdout" is a specially handled file.
+  files = ["stdout", "/tmp/metrics.out"]
+
+  ### Data format to output. This can be "influx" or "graphite"
+  ### Each data format has it's own unique set of configuration options, read
+  ### more about them here:
+  ### https://github.com/influxdata/telegraf/blob/master/DATA_FORMATS_OUTPUT.md
+  data_format = "influx"
+
+  prefix = "telegraf"
+```