# Configuration

Telegraf's configuration file is written using
[TOML](https://github.com/toml-lang/toml#toml).

[View the telegraf.conf config file with all available
plugins](/etc/telegraf.conf).

## Generating a Configuration File

A default config file can be generated by telegraf:

```
telegraf config > telegraf.conf
```

To generate a file with specific inputs and outputs, you can use the
--input-filter and --output-filter flags:

```
telegraf --input-filter cpu:mem:net:swap --output-filter influxdb:kafka config
```

### Environment Variables

Environment variables can be used anywhere in the config file, simply prepend
them with $. For strings the variable must be within quotes (ie, "$STR_VAR"),
for numbers and booleans they should be plain (ie, $INT_VAR, $BOOL_VAR)

When using the `.deb` or `.rpm` packages, you can define environment variables
in the `/etc/default/telegraf` file.

### Configuration file locations

The location of the configuration file can be set via the `--config` command
line flag.

When the `--config-directory` command line flag is used files ending with
`.conf` in the specified directory will also be included in the Telegraf
configuration.

On most systems, the default locations are `/etc/telegraf/telegraf.conf` for
the main configuration file and `/etc/telegraf/telegraf.d` for the directory of
configuration files.

### Global Tags

Global tags can be specified in the `[global_tags]` section of the config file
in key="value" format. All metrics being gathered on this host will be tagged
with the tags specified here.

### Agent Configuration

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

* **interval**: Default data collection interval for all inputs
* **round_interval**: Rounds collection interval to 'interval'
ie, if interval="10s" then always collect on :00, :10, :20, etc.
* **metric_batch_size**: Telegraf will send metrics to output in batch of at
most metric_batch_size metrics.
* **metric_buffer_limit**: Telegraf will cache metric_buffer_limit metrics
for each output, and will flush this buffer on a successful write.
This should be a multiple of metric_batch_size and could not be less
than 2 times metric_batch_size.
* **collection_jitter**: Collection jitter is used to jitter
the collection by a random amount.
Each plugin will sleep for a random time within jitter before collecting.
This can be used to avoid many plugins querying things like sysfs at the
same time, which can have a measurable effect on the system.
* **flush_interval**: Default data flushing interval for all outputs.
You should not set this below
interval. Maximum flush_interval will be flush_interval + flush_jitter
* **flush_jitter**: Jitter the flush interval by a random amount.
This is primarily to avoid
large write spikes for users running a large number of telegraf instances.
ie, a jitter of 5s and flush_interval 10s means flushes will happen every 10-15s.
* **precision**:
   By default or when set to "0s", precision will be set to the same
   timestamp order as the collection interval, with the maximum being 1s.
   Precision will NOT be used for service inputs. It is up to each individual
   service input to set the timestamp at the appropriate precision.
   Valid time units are "ns", "us" (or "µs"), "ms", "s".

* **logfile**: Specify the log file name. The empty string means to log to stderr.
* **debug**: Run telegraf in debug mode.
* **quiet**: Run telegraf in quiet mode (error messages only).
* **hostname**: Override default hostname, if empty use os.Hostname().
* **omit_hostname**: If true, do no set the "host" tag in the telegraf agent.

### Input Configuration

The following config parameters are available for all inputs:

* **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.
* **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.

The [metric filtering](#metric-filtering) parameters can be used to limit what metrics are
emitted from the input plugin.

### Output Configuration

- **flush_interval**: The maximum time between flushes.  Use this setting to
  override the agent `flush_interval` on a per plugin basis.
- **metric_batch_size**: The maximum number of metrics to send at once.  Use
  this setting to override the agent `metric_batch_size` on a per plugin basis.
- **metric_buffer_limit**: The maximum number of unsent metrics to buffer.
  Use this setting to override the agent `metric_buffer_limit` on a per plugin
  basis.

The [metric filtering](#metric-filtering) parameters can be used to limit what metrics are
emitted from the output plugin.

### Aggregator Configuration

The following config parameters are available for all aggregators:

* **period**: The period on which to flush & clear each aggregator. All metrics
that are sent with timestamps outside of this period will be ignored by the
aggregator.
* **delay**: The delay before each aggregator is flushed. This is to control
how long for aggregators to wait before receiving metrics from input plugins,
in the case that aggregators are flushing and inputs are gathering on the
same interval.
* **drop_original**: If true, the original metric will be dropped by the
aggregator and will not get sent to the output plugins.
* **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.

The [metric filtering](#metric-filtering) parameters can be used to limit what metrics are
handled by the aggregator.  Excluded metrics are passed downstream to the next
aggregator.

### Processor Configuration

The following config parameters are available for all processors:

* **order**: This is the order in which the processor(s) get executed. If this
is not specified then processor execution order will be random.

The [metric filtering](#metric-filtering) parameters can be used to limit what metrics are
handled by the processor.  Excluded metrics are passed downstream to the next
processor.

<a id="measurement-filtering"></a>
### Metric Filtering

Metric filtering can be configured per plugin on any input, output, processor,
and aggregator plugin.  Filters fall under two categories: Selectors and
Modifiers.

#### Selectors

Selector filters include or exclude entire metrics.  When a metric is excluded
from a Input or an Output plugin, the metric is dropped.  If a metric is
excluded from a Processor or Aggregator plugin, it is skips the plugin and is
sent onwards to the next stage of processing.

- **namepass**:
An array of glob pattern strings.  Only metrics whose measurement name matches
a pattern in this list are emitted.

- **namedrop**:
The inverse of `namepass`.  If a match is found the metric is discarded. This
is tested on metrics after they have passed the `namepass` test.

- **tagpass**:
A table mapping tag keys to arrays of glob pattern strings.  Only metrics
that contain a tag key in the table and a tag value matching one of its
patterns is emitted.

- **tagdrop**:
The inverse of `tagpass`.  If a match is found the metric is discarded. This
is tested on metrics after they have passed the `tagpass` test.

#### Modifiers

Modifier filters remove tags and fields from a metric.  If all fields are
removed the metric is removed.

- **fieldpass**:
An array of glob pattern strings.  Only fields whose field key matches a
pattern in this list are emitted.

- **fielddrop**:
The inverse of `fieldpass`.  Fields with a field key matching one of the
patterns will be discarded from the metric.  This is tested on metrics after
they have passed the `fieldpass` test.

- **taginclude**:
An array of glob pattern strings.  Only tags with a tag key matching one of
the patterns are emitted.  In contrast to `tagpass`, which will pass an entire
metric based on its tag, `taginclude` removes all non matching tags from the
metric.  Any tag can be filtered including global tags and the agent `host`
tag.

- **tagexclude**:
The inverse of `taginclude`. Tags with a tag key matching one of the patterns
will be discarded from the metric.  Any tag can be filtered including global
tags and the agent `host` tag.

### 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
[global_tags]
  dc = "denver-1"

[agent]
  interval = "10s"

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

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

#### Input Config: tagpass and tagdrop

**NOTE** `tagpass` and `tagdrop` parameters must be defined at the _end_ of
the plugin definition, otherwise subsequent plugin config options will be
interpreted as part of the tagpass/tagdrop map.

```toml
[[inputs.cpu]]
  percpu = true
  totalcpu = false
  fielddrop = ["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: fieldpass and fielddrop

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

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

#### Input Config: namepass and namedrop

```toml
# Drop all metrics about containers for kubelet
[[inputs.prometheus]]
  urls = ["http://kube-node-1:4194/metrics"]
  namedrop = ["container_*"]

# Only store rest client related metrics for kubelet
[[inputs.prometheus]]
  urls = ["http://kube-node-1:4194/metrics"]
  namepass = ["rest_client_*"]
```

#### Input Config: taginclude and tagexclude

```toml
# Only include the "cpu" tag in the measurements for the cpu plugin.
[[inputs.cpu]]
  percpu = true
  totalcpu = true
  taginclude = ["cpu"]

# Exclude the "fstype" tag from the measurements for the disk plugin.
[[inputs.disk]]
  tagexclude = ["fstype"]
```

#### 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`

NOTE: Order matters, the `[inputs.cpu.tags]` table must be at the _end_ of the
plugin definition.

```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"
  fielddrop = ["cpu_time*"]
```

#### Output Configuration Examples:

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

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

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

#### Aggregator Configuration Examples:

This will collect and emit the min/max of the system load1 metric every
30s, dropping the originals.

```toml
[[inputs.system]]
  fieldpass = ["load1"] # collects system load1 metric.

[[aggregators.minmax]]
  period = "30s"        # send & clear the aggregate every 30s.
  drop_original = true  # drop the original metrics.

[[outputs.file]]
  files = ["stdout"]
```

This will collect and emit the min/max of the swap metrics every
30s, dropping the originals. The aggregator will not be applied
to the system load metrics due to the `namepass` parameter.

```toml
[[inputs.swap]]

[[inputs.system]]
  fieldpass = ["load1"] # collects system load1 metric.

[[aggregators.minmax]]
  period = "30s"        # send & clear the aggregate every 30s.
  drop_original = true  # drop the original metrics.
  namepass = ["swap"]   # only "pass" swap metrics through the aggregator.

[[outputs.file]]
  files = ["stdout"]
```

#### Processor Configuration Examples:

Print only the metrics with `cpu` as the measurement name, all metrics are
passed to the output:
```toml
[[processors.printer]]
  namepass = "cpu"

[[outputs.file]]
  files = ["/tmp/metrics.out"]
```
