# Prometheus Output Plugin

This plugin starts a [Prometheus](https://prometheus.io/) Client, it exposes
all metrics on `/metrics` (default) to be polled by a Prometheus server.

### Configuration

```toml
[[outputs.prometheus_client]]
  ## Address to listen on.
  listen = ":9273"

  ## Metric version controls the mapping from Telegraf metrics into
  ## Prometheus format.  When using the prometheus input, use the same value in
  ## both plugins to ensure metrics are round-tripped without modification.
  ##
  ##   example: metric_version = 1;
  ##            metric_version = 2; recommended version
  # metric_version = 1

  ## Use HTTP Basic Authentication.
  # basic_username = "Foo"
  # basic_password = "Bar"

  ## If set, the IP Ranges which are allowed to access metrics.
  ##   ex: ip_range = ["192.168.0.0/24", "192.168.1.0/30"]
  # ip_range = []

  ## Path to publish the metrics on.
  # path = "/metrics"

  ## Expiration interval for each metric. 0 == no expiration
  # expiration_interval = "60s"

  ## Collectors to enable, valid entries are "gocollector" and "process".
  ## If unset, both are enabled.
  # collectors_exclude = ["gocollector", "process"]

  ## Send string metrics as Prometheus labels.
  ## Unless set to false all string metrics will be sent as labels.
  # string_as_label = true

  ## If set, enable TLS with the given certificate.
  # tls_cert = "/etc/ssl/telegraf.crt"
  # tls_key = "/etc/ssl/telegraf.key"

  ## Set one or more allowed client CA certificate file names to
  ## enable mutually authenticated TLS connections
  # tls_allowed_cacerts = ["/etc/telegraf/clientca.pem"]

  ## Export metric collection time.
  # export_timestamp = false
```

### Metrics

Prometheus metrics are produced in the same manner as the [prometheus serializer][].

[prometheus serializer]: /plugins/serializers/prometheus/README.md#Metrics
