StatsD-Bridge

StatsD-Bridge receives StatsD-style metrics and exports them as Prometheus metrics.

Overview

To pipe metrics from an existing StatsD environment into Prometheus, configure StatsD's repeater backend to repeat all received packets to a StatsD-Bridge process. This bridge translates StatsD metrics to Prometheus metrics via configured mapping rules.

+----------+                     +-----------------+                        +--------------+
|  StatsD  |---(UDP repeater)--->|  StatsD-Bridge  |<---(scrape /metrics)---|  Prometheus  |
+----------+                     +-----------------+                        +--------------+

Building and Running

$ go build
$ ./statsd_bridge --help
Usage of ./statsd_bridge:
  -statsd.listen-address=":9125": The UDP address on which to receive statsd metric lines.
  -statsd.mapping-config="": Metric mapping configuration file name.
  -web.listen-address=":9102": The address on which to expose the web interface and generated Prometheus metrics.
  -web.telemetry-path="/metrics": Path under which to expose metrics.

Tests

$ go test

Metric Mapping and Configuration

The StatsD-Bridge can be configured to translate specific dot-separated StatsD metrics into labeled Prometheus metrics via a simple mapping language. A mapping definition starts with a line matching the StatsD metric in question, with *s acting as wildcards for each dot-separated metric component. The lines following the matching expression must contain one label="value" pair each, and at least define the metric name (label name name). The Prometheus metric is then constructed from these labels. $n-style references in the label value are replaced by the n-th wildcard match in the matching line, starting at 1. Multiple matching definitions are separated by one or more empty lines. The first mapping rule that matches a StatsD metric wins.

Metrics that don't match any mapping in the configuration file are translated into Prometheus metrics without any labels and with certain characters escaped (_ -> __; - -> __; . -> _).

In general, the different metric types are translated as follows, with certain suffixes appended to the Prometheus metric names:

StatsD gauge   -> Prometheus gauge (suffix `_gauge`)

StatsD counter -> Prometheus counter (suffix `_counter`)

StatsD timer   -> Prometheus summary (suffix `_timer`)        <-- indicates timer quantiles
               -> Prometheus counter (suffix `_timer_total`)  <-- indicates total time spent
               -> Prometheus counter (suffix `_timer_count`)  <-- indicates total number of timer events

An example mapping configuration:

test.dispatcher.*.*.*
name="dispatcher_events"
processor="$1"
action="$2"
outcome="$3"
job="test_dispatcher"

*.signup.*.*
name="signup_events"
provider="$2"
outcome="$3"
job="$1_server"

This would transform these example StatsD metrics into Prometheus metrics as follows:

test.dispatcher.FooProcessor.send.success (counter)
 => dispatcher_events_counter{processor="FooProcessor", action="send", outcome="success", job="test_dispatcher"}

foo_product.signup.facebook.failure (counter)
 => signup_events_counter{provider="facebook", outcome="failure", job="foo_product_server"}
 
test.web-server.foo.bar (gauge)
 => test_web__server_foo_bar_gauge{}