# Splunk Metrics serializer

The Splunk Metrics serializer outputs metrics in the
[Splunk metric HEC JSON format][splunk-format].

It can be used to write to a file using the file output, or for sending metrics
to a HEC using the standard telegraf HTTP output. If you're using the HTTP
output, this serializer knows how to batch the metrics so you don't end up with
an HTTP POST per metric.

[splunk-format]: http://dev.splunk.com/view/event-collector/SP-CAAAFDN#json

An example event looks like:

```javascript
{
  "time": 1529708430,
  "event": "metric",
  "host": "patas-mbp",
  "fields": {
    "_value": 0.6,
    "cpu": "cpu0",
    "dc": "mobile",
    "metric_name": "cpu.usage_user",
    "user": "ronnocol"
  }
}
```

In the above snippet, the following keys are dimensions:

* cpu
* dc
* user

## Using Multimetric output

Starting with Splunk Enterprise and Splunk Cloud 8.0, you can now send multiple
metric values in one payload. This means, for example, that you can send all of
your CPU stats in one JSON struct, an example event looks like:

```javascript
{
  "time": 1572469920,
  "event": "metric",
  "host": "mono.local",
  "fields": {
    "class": "osx",
    "cpu": "cpu0",
    "metric_name:telegraf.cpu.usage_guest": 0,
    "metric_name:telegraf.cpu.usage_guest_nice": 0,
    "metric_name:telegraf.cpu.usage_idle": 65.1,
    "metric_name:telegraf.cpu.usage_iowait": 0,
    "metric_name:telegraf.cpu.usage_irq": 0,
    "metric_name:telegraf.cpu.usage_nice": 0,
    "metric_name:telegraf.cpu.usage_softirq": 0,
    "metric_name:telegraf.cpu.usage_steal": 0,
    "metric_name:telegraf.cpu.usage_system": 10.2,
    "metric_name:telegraf.cpu.usage_user": 24.7,
  }
}
```

In order to enable this mode, there's a new option `splunkmetric_multimetric`
that you set in the appropriate output module you plan on using.

## Using with the HTTP output

To send this data to a Splunk HEC, you can use the HTTP output, there are some
custom headers that you need to add to manage the HEC authorization, here's a
sample config for an HTTP output:

```toml
[[outputs.http]]
  ## URL is the address to send metrics to
  url = "https://localhost:8088/services/collector"

  ## Timeout for HTTP message
  # timeout = "5s"

  ## HTTP method, one of: "POST" or "PUT"
  # method = "POST"

  ## HTTP Basic Auth credentials
  # username = "username"
  # password = "pa$$word"

  ## Optional TLS Config
  # tls_ca = "/etc/telegraf/ca.pem"
  # tls_cert = "/etc/telegraf/cert.pem"
  # tls_key = "/etc/telegraf/key.pem"
  ## Use TLS but skip chain & host verification
  # insecure_skip_verify = false

  ## Data format to output.
  ## Each data format has it's own unique set of configuration options, read
  ## more about them here:
  ## https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_OUTPUT.md
  data_format = "splunkmetric"

  ## Provides time, index, source overrides for the HEC
  splunkmetric_hec_routing = true
  # splunkmetric_multimetric = true
  # splunkmetric_omit_event_tag = false

  ## Additional HTTP headers
  [outputs.http.headers]
    # Should be set manually to "application/json" for json data_format
    Content-Type = "application/json"
    Authorization = "Splunk xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
    X-Splunk-Request-Channel = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
```

## Overrides

You can override the default values for the HEC token you are using by adding
additional tags to the config file.

The following aspects of the token can be overridden with tags:

* index
* source

You can either use `[global_tags]` or using a more advanced configuration
[as documented][global_options].

Such as this example which overrides the index just on the cpu metric:

```toml
[[inputs.cpu]]
  percpu = false
  totalcpu = true
  [inputs.cpu.tags]
    index = "cpu_metrics"
```

[global_options]: /docs/CONFIGURATION.md

## Using with the File output

You can use the file output when running telegraf on a machine with a Splunk
forwarder.

A sample event when `hec_routing` is false (or unset) looks like:

```javascript
{
    "_value": 0.6,
    "cpu": "cpu0",
    "dc": "mobile",
    "metric_name": "cpu.usage_user",
    "user": "ronnocol",
    "time": 1529708430
}
```

Data formatted in this manner can be ingested with a simple `props.conf` file
that looks like this:

```ini
[telegraf]
category = Metrics
description = Telegraf Metrics
pulldown_type = 1
DATETIME_CONFIG =
NO_BINARY_CHECK = true
SHOULD_LINEMERGE = true
disabled = false
INDEXED_EXTRACTIONS = json
KV_MODE = none
TIMESTAMP_FIELDS = time
```

An example configuration of a file based output is:

```toml
 # Send telegraf metrics to file(s)
[[outputs.file]]
   ## Files to write to, "stdout" is a specially handled file.
   files = ["/tmp/metrics.out"]

   ## Data format to output.
   ## Each data format has its own unique set of configuration options, read
   ## more about them here:
   ## https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_OUTPUT.md
   data_format = "splunkmetric"
   splunkmetric_hec_routing = false
   splunkmetric_multimetric = true
   splunkmetric_omit_event_tag = false
```

## Non-numeric metric values

Splunk supports only numeric field values, so serializer would silently drop
metrics with the string values. For some cases it is possible to workaround
using the [enum processor][enum_plugin]. Example, provided below doing this for
the `docker_container_health.health_status` metric:

```toml
# splunkmetric does not support string values
[[processors.enum]]
  namepass = ["docker_container_health"]
  [[processors.enum.mapping]]
    ## Name of the field to map
    field = "health_status"
    [processors.enum.mapping.value_mappings]
    starting = 0
    healthy = 1
    unhealthy = 2
    none = 3
```

[enum_plugin]: /plugins/processors/enum/README.md
