# Telegraf Internal Input Plugin

The `internal` plugin collects metrics about the telegraf agent itself.

Note that some metrics are aggregates across all instances of one type of
plugin.

## Configuration

```toml
# Collect statistics about itself
[[inputs.internal]]
  ## If true, collect telegraf memory stats.
  # collect_memstats = true
```

## Measurements & Fields

memstats are taken from the Go runtime: <https://golang.org/pkg/runtime/#MemStats>

- internal_memstats
  - alloc_bytes
  - frees
  - heap_alloc_bytes
  - heap_idle_bytes
  - heap_in_use_bytes
  - heap_objects_bytes
  - heap_released_bytes
  - heap_sys_bytes
  - mallocs
  - num_gc
  - pointer_lookups
  - sys_bytes
  - total_alloc_bytes

agent stats collect aggregate stats on all telegraf plugins.

- internal_agent
  - gather_errors
  - metrics_dropped
  - metrics_gathered
  - metrics_written

internal_gather stats collect aggregate stats on all input plugins
that are of the same input type. They are tagged with `input=<plugin_name>`
`version=<telegraf_version>` and `go_version=<go_build_version>`.

- internal_gather
  - gather_time_ns
  - metrics_gathered

internal_write stats collect aggregate stats on all output plugins
that are of the same input type. They are tagged with `output=<plugin_name>`
and `version=<telegraf_version>`.

- internal_write
  - buffer_limit
  - buffer_size
  - metrics_added
  - metrics_written
  - metrics_dropped
  - metrics_filtered
  - write_time_ns

internal_<plugin_name> are metrics which are defined on a per-plugin basis, and
usually contain tags which differentiate each instance of a particular type of
plugin and `version=<telegraf_version>`.

- internal_<plugin_name>
  - individual plugin-specific fields, such as requests counts.

## Tags

All measurements for specific plugins are tagged with information relevant
to each particular plugin and with `version=<telegraf_version>`.

## Example Output

```shell
internal_memstats,host=tyrion alloc_bytes=4457408i,sys_bytes=10590456i,pointer_lookups=7i,mallocs=17642i,frees=7473i,heap_sys_bytes=6848512i,heap_idle_bytes=1368064i,heap_in_use_bytes=5480448i,heap_released_bytes=0i,total_alloc_bytes=6875560i,heap_alloc_bytes=4457408i,heap_objects_bytes=10169i,num_gc=2i 1480682800000000000
internal_agent,host=tyrion,go_version=1.12.7,version=1.99.0 metrics_written=18i,metrics_dropped=0i,metrics_gathered=19i,gather_errors=0i 1480682800000000000
internal_write,output=file,host=tyrion,version=1.99.0 buffer_limit=10000i,write_time_ns=636609i,metrics_added=18i,metrics_written=18i,buffer_size=0i 1480682800000000000
internal_gather,input=internal,host=tyrion,version=1.99.0 metrics_gathered=19i,gather_time_ns=442114i 1480682800000000000
internal_gather,input=http_listener,host=tyrion,version=1.99.0 metrics_gathered=0i,gather_time_ns=167285i 1480682800000000000
internal_http_listener,address=:8186,host=tyrion,version=1.99.0 queries_received=0i,writes_received=0i,requests_received=0i,buffers_created=0i,requests_served=0i,pings_received=0i,bytes_received=0i,not_founds_served=0i,pings_served=0i,queries_served=0i,writes_served=0i 1480682800000000000
```
