# Peep
`Telemetry.Metrics` reporter for Prometheus and StatsD (including Datadog).
Peep has some important differences from libraries like
`TelemetryMetricsPrometheus.Core` and `TelemetryMetricsStatsd`:
- Instead of sampling or on-demand aggregation of samples, Peep estimates
distributions using histograms.
- Instead of sending one datagram per telemetry event, Peep's StatsD reporting
runs periodically, batching all lines into the smallest number of datagram
packets possible while still obeying the configured `:mtu` setting.
To use it, start a reporter with `start_link/1`, providing a keyword list of
options (see `Peep.Options` for the schema against which options are validated).
```elixir
import Telemetry.Metrics
Peep.start_link(
name: MyPeep,
metrics: [
counter("http.request.count"),
sum("http.request.payload_size"),
last_value("vm.memory.total")
]
)
```
or put it under a supervisor:
```elixir
import Telemetry.Metrics
children = [
{Peep, [
name: MyPeep,
metrics: [
counter("http.request.count"),
sum("http.request.payload_size"),
last_value("vm.memory.total")
]
]}
]
Supervisor.start_link(children, ...)
```
By default, Peep does not emit StatsD data. It can be enabled by passing in
configuration with the `statsd` keyword. Peep's StatsD reporting supports Unix
Domain Sockets.
## What's Missing
Currently, there's no implementation of 'summary' metrics. Since histograms are
relatively inexpensive in Peep, we suggest you use 'distribution' metrics
instead.
## Installation
Peep package can be installed by adding `peep` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:peep, "~> 3.3"}
]
end
```
Documentation can be generated with [ExDoc](https://github.com/elixir-lang/ex_doc)
and published on [HexDocs](https://hexdocs.pm). Once published, the docs can
be found at <https://hexdocs.pm/peep>.
