# Telegraf Configuration

## Generating a Configuration File

A default Telegraf config file can be generated using the `-sample-config` flag,
like this: `telegraf -sample-config`

To generate a file with specific inputs and outputs, you can use the
`-input-filter` and `-output-filter` flags, like this:
`telegraf -sample-config -input-filter cpu:mem:net:swap -output-filter influxdb:kafka`

## Telegraf Agent Configuration

Telegraf has a few options you can configure under the `agent` section of the
config.

* **hostname**: The hostname is passed as a tag. By default this will be
the value returned by `hostname` on the machine running Telegraf.
You can override that value here.
* **interval**: How often to gather metrics. Uses a simple number +
unit parser, e.g. "10s" for 10 seconds or "5m" for 5 minutes.
* **debug**: Set to true to gather and send metrics to STDOUT as well as
InfluxDB.

## Input Configuration

There are some configuration options that are configurable per input:

* **name_override**: Override the base name of the measurement.
(Default is the name of the input).
* **name_prefix**: Specifies a prefix to attach to the measurement name.
* **name_suffix**: Specifies a suffix to attach to the measurement name.
* **tags**: A map of tags to apply to a specific input's measurements.
* **interval**: How often to gather this metric. Normal plugins use a single
global interval, but if one particular input should be run less or more often,
you can configure that here.

### Input Filters

There are also filters that can be configured per input:

* **pass**: An array of strings that is used to filter metrics generated by the
current input. Each string in the array is tested as a glob match against field names
and if it matches, the field is emitted.
* **drop**: The inverse of pass, if a field name matches, it is not emitted.
* **tagpass**: tag names and arrays of strings that are used to filter
measurements by the current input. Each string in the array is tested as a glob
match against the tag name, and if it matches the measurement is emitted.
* **tagdrop**: The inverse of tagpass. If a tag matches, the measurement is not
emitted. This is tested on measurements that have passed the tagpass test.

### Input Configuration Examples

This is a full working config that will output CPU data to an InfluxDB instance
at 192.168.59.103:8086, tagging measurements with dc="denver-1". It will output
measurements at a 10s interval and will collect per-cpu data, dropping any
fields which begin with `time_`.

```toml
[tags]
  dc = "denver-1"

[agent]
  interval = "10s"

# OUTPUTS
[[outputs.influxdb]]
  url = "http://192.168.59.103:8086" # required.
  database = "telegraf" # required.
  precision = "s"

# INPUTS
[[inputs.cpu]]
  percpu = true
  totalcpu = false
  # filter all fields beginning with 'time_'
  drop = ["time_*"]
```

### Input Config: tagpass and tagdrop

```toml
[[inputs.cpu]]
  percpu = true
  totalcpu = false
  drop = ["cpu_time"]
  # Don't collect CPU data for cpu6 & cpu7
  [inputs.cpu.tagdrop]
    cpu = [ "cpu6", "cpu7" ]

[[inputs.disk]]
  [inputs.disk.tagpass]
    # tagpass conditions are OR, not AND.
    # If the (filesystem is ext4 or xfs) OR (the path is /opt or /home)
    # then the metric passes
    fstype = [ "ext4", "xfs" ]
    # Globs can also be used on the tag values
    path = [ "/opt", "/home*" ]
```

### Input Config: pass and drop

```toml
# Drop all metrics for guest & steal CPU usage
[[inputs.cpu]]
  percpu = false
  totalcpu = true
  drop = ["usage_guest", "usage_steal"]

# Only store inode related metrics for disks
[[inputs.disk]]
  pass = ["inodes*"]
```

### Input config: prefix, suffix, and override

This plugin will emit measurements with the name `cpu_total`

```toml
[[inputs.cpu]]
  name_suffix = "_total"
  percpu = false
  totalcpu = true
```

This will emit measurements with the name `foobar`

```toml
[[inputs.cpu]]
  name_override = "foobar"
  percpu = false
  totalcpu = true
```

### Input config: tags

This plugin will emit measurements with two additional tags: `tag1=foo` and
`tag2=bar`

```toml
[[inputs.cpu]]
  percpu = false
  totalcpu = true
  [inputs.cpu.tags]
    tag1 = "foo"
    tag2 = "bar"
```

### Multiple inputs of the same type

Additional inputs (or outputs) of the same type can be specified,
just define more instances in the config file. It is highly recommended that
you utilize `name_override`, `name_prefix`, or `name_suffix` config options
to avoid measurement collisions:

```toml
[[inputs.cpu]]
  percpu = false
  totalcpu = true

[[inputs.cpu]]
  percpu = true
  totalcpu = false
  name_override = "percpu_usage"
  drop = ["cpu_time*"]
```

## Output Configuration

Telegraf also supports specifying multiple output sinks to send data to,
configuring each output sink is different, but examples can be
found by running `telegraf -sample-config`.

Outputs also support the same configurable options as inputs
(pass, drop, tagpass, tagdrop)

```toml
[[outputs.influxdb]]
  urls = [ "http://localhost:8086" ]
  database = "telegraf"
  precision = "s"
  # Drop all measurements that start with "aerospike"
  drop = ["aerospike*"]

[[outputs.influxdb]]
  urls = [ "http://localhost:8086" ]
  database = "telegraf-aerospike-data"
  precision = "s"
  # Only accept aerospike data:
  pass = ["aerospike*"]

[[outputs.influxdb]]
  urls = [ "http://localhost:8086" ]
  database = "telegraf-cpu0-data"
  precision = "s"
  # Only store measurements where the tag "cpu" matches the value "cpu0"
  [outputs.influxdb.tagpass]
    cpu = ["cpu0"]
```