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Riepete - Riemann Repeater

Receives statsd packets and repeats them to riemann.

Build Status

Purpose

If you are using statsd to aggregate your metrics you changed your applications to send an UDP packet every time you want a metric to be generated.

The purpose of riepete is to help with the migration to riemann without the need to change your app to send metrics to riemann instead of statsd.

This way you can have both statsd, graphite (or whatever backend you have for statsd) and riemann running in parallel without changing your applications.

One possible setup is illustrated in the following diagram:

App 1 --+
        |   +--------+        +---------+         +---------+
App 2 --+-->+ statsd |------->| riepete |-------->| riemann |
        |   +---+----+        +---------+         +---------+
App 3 --+       |
        |       |   +----------+
App 4 --+       +-->| graphite |
                    +----------+

riemann actually gives you the same features as statsd and much more, you can decide to stop using it entirely, also without changing your app:

App 1 --+
        |   +---------+         +---------+
App 2 --+-->| riepete |-------->| riemann |
        |   +---------+         +----+----+
App 3 --+                            |
        |           +----------+     |
App 4 --+           | graphite |<----+
                    +----------+

Since riepete understands statsd, you still don't need to change your applications at this point and you can do so incrementally, or not at all.

Supported metrics

Currently riepete supports as subset of statsd metrics as defined in https://github.com/etsy/statsd/blob/master/docs/metric_types.md.

In particular, riepete does not support:

  • sets

  • gauges with -/+ modifiers.

    Gauges will still be parsed and accepted by riepete, but they will be mapped into metrics with the received positive/negative value and sent to riemann.

Metrics sent to riemann

For each metric received by riepete a new event is sent to riemann.

The event sent to riemann has:

  • Its status set to ok
  • Its hostname set to the hostname where riepete is running
  • Its description and service set to the key name used in the statsd metric
  • Its tags set to statsd, riepete, <metric_type> where <metric_type> is one of Counter, Gauge or Timer.

Caveats

Metrics are repeated to riemann without any type of aggregation. Each statsd UDP packet will result in a metric being sent to riemann. If you need some kind of aggregation you will need to do it in riemann. See the next section for an example on how to do this.

Installing

The latest version is available at releases/latest

You can extract this file into a directory and just run bin/start. This will start riepete in the foregrou with the default settings. Here a simple way to start:

wget https://github.com/simao/riepete/releases/download/v0.0.2/riepete-0.0.2.tgz
tar xvf riepete-0.0.2.tgz
cd riepete-0.0.2
bin/start

You can adjust settings editing riepete/config/riepete.json.

You can read more about deploying an akka app in this post

Alternatively, you can clone this repo and built riepete with sbt dist.

Example riemann.config file

Since riepete does not aggregate any metrics, you will need to do this yourself if you need to show aggregated results.

This section shows some examples you can you in your riemann.config.

Rate of events received from riepete

This creates an event every five seconds with with :metric set to the number of events received per second in that interval.

(tagged "riepete"
  (with {:metric 1 :state "ok" :service "riepete-events/sec"}
        (rate 5 index)))

Calculate rate of events for each statsd metric type

This generates a new event every 5 seconds with :metric set to the rate per second of the last 5 seconds. For example, riepete-timers/sec will show you how many timers per second riemann received from riepete in the last 5 seconds.

(defn as-rate-if-tagged [tags new-name & children]
    (tagged tags
            (with {:metric 1 :state "ok" :service new-name}
                  (rate 5
                        (fn stream [event]
                          (call-rescue event children))))))

(as-rate-if-tagged ["riepete" "timer"] "riepete-timers/sec" index)

(as-rate-if-tagged ["riepete" "counter"] "riepete-counters/sec" index)

(as-rate-if-tagged ["riepete" "gauge"] "riepete-gauges/sec" index)

Calculate rate of events for all counters

This generates a new event for each counter received from riemann. Each generated event will have the rate of the corresponding event in the last 5 seconds. Since riepete does not use any aggregation, this must be done by riepete, but it's as easy as using this simple code:

(tagged-all ["riepete" "statsd" "counter"]
            (by :service
                (adjust [:service #(str "stats.counts." % ".rate")]
                        (rate 5 index))))

Benchmarking

In the benchmark directory you will find a small clojure app that can be used to send a large number of requests to riepete using a non uniform distribution.

This benchmark was executed running on an ec2 c3.large instance sending images to another c3.large instance where riepete was deployed.

Riepete was able to handle and forward to riemann about 12000 events/second, before the OS started dropping incoming UDP packets.

Benchmarks are just benchmarks and this one certainly has it's problems and can be improved, increasing UDP buffer sizes for example. I will explore these possibilities in future releases. For now 12000 event/s is enough for the purposes riepete is being used.

Contributing

Riepete is written in Scala and uses Akka.

No pull request is too small, documentation improvements also very welcome!

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