StatsD

A network daemon for aggregating statistics (counters and timers), rolling them up, then sending them to graphite.

Installation

gem install statsd

Configuration

Create config.yml to your liking.

Example config.yml --- bind: 127.0.0.1 port: 8125

# Flush interval should be your finest retention in seconds
flush_interval: 10

# Graphite
graphite_host: localhost
graphite_port: 2003

Server

Run the server:

Flush to Graphite (default): statsd -c config.yml

Client

In your client code:

require 'rubygems'
require 'statsd'
STATSD = Statsd::Client.new('localhost',8125)

STATSD.increment('some_counter') # basic incrementing
STATSD.increment('system.nested_counter', 0.1) # incrementing with sampling (10%)

STATSD.decrement(:some_other_counter) # basic decrememting using a symbol
STATSD.decrement('system.nested_counter', 0.1) # decrementing with sampling (10%)

STATSD.timing('some_job_time', 20) # reporting job that took 20ms
STATSD.timing('some_job_time', 20, 0.05) # reporting job that took 20ms with sampling (5% sampling)

Concepts

  • buckets Each stat is in it's own "bucket". They are not predefined anywhere. Buckets can be named anything that will translate to Graphite (periods make folders, etc)

  • values Each stat will have a value. How it is interpreted depends on modifiers

  • flush After the flush interval timeout (default 10 seconds), stats are munged and sent over to Graphite.

Counting

gorets:1|c

This is a simple counter. Add 1 to the "gorets" bucket. It stays in memory until the flush interval.

Timing

glork:320|ms

The glork took 320ms to complete this time. StatsD figures out 90th percentile, average (mean), lower and upper bounds for the flush interval.

Sampling

gorets:1|c|@0.1

Tells StatsD that this counter is being sent sampled ever 1/10th of the time.

Guts

Graphite

Graphite uses "schemas" to define the different round robin datasets it houses (analogous to RRAs in rrdtool):

[stats]
priority = 110
pattern = ^stats\..*
retentions = 10:2160,60:10080,600:262974

That translates to:

  • 6 hours of 10 second data (what we consider "near-realtime")
  • 1 week of 1 minute data
  • 5 years of 10 minute data

This has been a good tradeoff so far between size-of-file (round robin databases are fixed size) and data we care about. Each "stats" database is about 3.2 megs with these retentions.

Inspiration

Etsy's blog post.

StatsD was inspired (heavily) by the project (of the same name) at Flickr. Here's a post where Cal Henderson described it in depth: Counting and timing. Cal re-released the code recently: Perl StatsD