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README.md

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Triton Digital Counters

tritondigital-counters allows applications to publish metrics in monitoring systems as easy as logging, from Scala, Java, or any JVM language, with minimal overhead.

Currently, the library supports the following integrations:

  • Datadog
  • Logback
  • Docker
  • Akka
  • Codahale metrics

tritondigital-counters act in a similar spirit to the Codahale metrics, but is adding the publication to a timeseries database, and contextual tags that makes systems like OpenTSDB and Datadog so powerfull for monitoring applications.

Features

tritondigital-counters supports publication to the following back-ends:

  • Datadog
  • Logback logs

tritondigital-counters can monitor the following part of your application out of the box:

  • application lifecycle (start / stop)
  • Logback ERROR and WARNING log entries
  • Akka actors
  • Codahale metrics

But the most important feature is it allows you to publish your own metrics easily.

Concepts

Most of the concepts are identical to Codahale metrics one. Please refer to the Codahale metrics documentation for what constitute a gauge, a counter, a marker, an histogram, and a timer.

tritondigital-counters adds the notion of tags, inherited from the OpenTSDB or Datadog tags. A tag is a bit of metadata associated with a metrics that allows for fine grained queries when retrieving timeseries. Example of tags are:

  • application name
  • host name
  • response status code
  • etc...

Behaviour

During normal conditions, tritondigital-counters will publish a snapshot of the metrics every publication interval (15 seconds by default).

The internal aggregation of metrics is based on Codahale Metrics, so it is fast. Although the metrics are published every few seconds, your application can update them thousends of time per seconds.

tritondigital-counters tries to be a good citizen. It is publishing metrics that have stable values less often (10 mins instead of the regular publication interval). This makes monitoring a lot of stable metrics not an issue.

When the remote timeseries database is not responding, it will drop the current metrics publication round, and tries to reconnect after the next publication interval.

If for whatever reason, publication takes longer than the interval between publication, some publication rounds will be skipped. This is making tritondigital-counters to peaks where a lot of metrics need to be published.

Publication time is jittered, so as to avoid resonance phenomena that could harm the target timeseries database.

Getting started

Start by adding the dependency to your project:

For Maven:

    <dependency>
        <groupId>com.tritondigital</groupId>
        <artifactId>tritondigital-counters_2.10</artifactId>
        <version>1.0.2</version>
    </dependency>

For SBT:

    libraryDependencies += "com.tritondigital" %% "tritondigital-counters" % "1.0.2"

You can then start the monitoring process. tritondigital-counters is using akka-io for fast, efficient, and non blocking IO, so you will need to pass it an actor system:

In Java:

    ActorSystem actorSystem = ActorSystem.create();
    Metrics metrics = new MetricsBuilder(actorSystem)
        .publishToDatadog()
        .build();

In Scala:

    val actorSystem = ActorSystem()
    val metrics = new MetricsBuilder(actorSystem)
        .publishToDatadog
        .build

Configuration

tritondigital-counters is using the typesafe config. You can look at the documentation and default config values in src/main/resources/reference.conf.

Publishing to Datadog

For activating the publication to datadog:

    Metrics metrics = new MetricsBuilder(actorSystem)
        .publishToDatadog()
        .build();

Datadog configuration

You will need datadog agent to run locally on the host. If running elsewhere, you can adjust the following configuration settings:

  • tritondigital_counters.datadog.host: the datadog agent host name or ip (default: localhost)
  • tritondigital_counters.datadog.port: the datadog agent host name or ip (default: 8125)

Datadog on Docker

If you are running your application and the Datadog agent in Docker containers, you simply need to link the agent using the "datadog" alias:

    docker run -dt --link my-datadog-container-name:datadog my-app

Limiting the number of metrics sent to Datadog

Datadog encourages you to think hard which metrics you send to their system. You can adjust which metrics you send to them by implementing a filter:

In Java:

    import com.tritondigital.counters.MetricFilter

    public class MyDGFilter extends MetricFilter {
      public Iterable[Metric] filter(metrics: Iterable[Metric]) {
        // Do your filtering here
      }
    }

    ...

    Metrics metrics = new MetricsBuilder(actorSystem)
        .publishToDatadog()
        .withDatadogFilter(new MyDGFilter())
        .build();

In Scala:

    import com.tritondigital.counters.MetricFilter

    class MyDGFilter extends ScalaMetricFilter {
      def filter(metrics: Iterable[Metric]) = {
        // Do your filtering here
      }
    }

    ...

    val metrics = new MetricsBuilder(actorSystem)
        .publishToDatadog()
        .withDatadogFilter(new MyDGFilter())
        .build()

If all you need to do is have a white list of metrics to send, a filter is readily useable:

    Metrics metrics = new MetricsBuilder(actorSystem)
        .publishToDatadog()
        .withDatadogFilter(new MetricPrefixFilter(new String[]{ "log.", "my-app." }))
        .build();

Publishing to Logback

For debugging or in the tests, it can be usefull to publish the metrics value in your application log:

    Metrics metrics = new MetricsBuilder(actorSystem)
        .publishToLogback()
        .build();

Publishing new metrics

You can now publish various kind of metrics:

    // Counters
    metrics.incrementCounter("some.metric.without.tags");

    // Meters
    metrics.markMeter("some.meter");

    // Histograms
    metrics.updateHistogram("some.histogram", 88);

    // Timers
    metrics.updateTimer("some.timer", 67, TimeUnit.MILLIS);

    // Gauges
    metrics.setGaugeValue("some.gauge", 1.45);

    // All methods support contextual tags
    metrics.incrementCounter("some.metric.with.tags", new Tag("custom-tag-1", "value"), new Tag("custom-tag-2", "value"));
    metrics.incrementCounter("some.metric.with.tags", 10, new Tag("custom-tag-1", "value"), new Tag("custom-tag-2", "value"));

That being said, timeseries databases only support gauges. So tritondigital-counters is creating gauges out of those high level metrics. Here are the gauges actually published by tritondigital-counters:

Gauges

The gauges are published as is.

Counters

The counters are published as is.

Meters

The following gauges are published for meters:

  • Suffix: .count

  • The total number of time the meter has been marked (= how many data points)

  • Suffix: .m1

  • The 1 minute moving average

Histograms

The following gauges are published for histograms:

  • Suffix: .count

  • The total number of time the histogram has been updated (= how many data points)

  • Suffix: .median

  • The median value (.50th quantile)

  • Suffix: .p75

  • .75th quantile

  • Suffix: .p99

  • .99th quantile

Timers

A timer is an histogram and a meter, and thus the gauges for both meters and histograms are published. The values' unit are milliseconds.

Built-in metrics

Out of the box, some metrics are published.

JMX basic metrics

Monitoring Logback

If you want tritondigital-counters to monitor your logs, you can activate it by:

    Metrics metrics = new MetricsBuilder(actorSystem)
        .monitorLogback()
        .build();

This will yield the following metrics:

  • log.error.count and log.error.m1: errors logged in Logback. 2 tags are given: exception which is the exception class anem that have been logged (if any) and inner which is the inner exception class name of that exception (if any).
  • log.warn.count and log.warn.m1: warnings logged in Logback. 2 tags are given: exception which is the exception class anem that have been logged (if any) and inner which is the inner exception class name of that exception (if any).

Monitoring Akka actors

You can monitor your Akka actors. For that, a utility wrapping the receive method is provided.

In Java:

    import com.tritondigital.counters.Metrics;
    import com.tritondigital.counters.akka.ActorWithMetrics;

    public class MyActor extends ActorWithMetrics {
        public MyActor(Metrics metrics) {
            super(metrics);
        }
        @Override
        public void wrappedOnReceive(Object message) throws Exception {
            // Your logic that you used to place in onReceive()
        }
    }

In Scala:

    import com.tritondigital.counters.Metrics
    import com.tritondigital.counters.akka.ActorMetrics

    class MyActor(val metrics: Metrics) extends Actor with ActorMetrics {
      def wrappedReceive = {
        case message =>
          // Your logic that you used to place in receive {}
      }
    }

This will yield the following metrics:

  • akka.actor.message (timer with .count, .m1, .median, .p75, and .p99): number of message processed, and time to process them. 2 tags: path, for the actor path, and mclass for the message class name.

Appending global tags to all metrics

    Metrics metrics = new MetricsBuilder(actorSystem)
        .addGlobalTag("my-app-tag-name", "my-app-tag-value")
        .build();

Providing custom gauges at publication time

Sometimes, you have access to gauges at all time, and all you need is to "plug" those values at publication time. You can achieve that by implimenting a custom metrics provider:

    import com.tritondigital.counters.MetricsProvider
    import scala.concurrent.Future

    public class MyCustomProvider implements MetricsProvider {
      public Future<Metric[]> provide() {
        // Return your metrics here
      }
    }

    ...

    Metrics metrics = new MetricsBuilder(actorSystem)
        .addProvider(new MyCustomProvider())
        .build();

Publishing Codahale Metrics

A provider exists for Codahale Metrics registry. You don't need a registry yourself (this is redundant with the com.tritondigital.counters.Metrics), but if an other library is providing one, you can make tritondigital-counters publish this library's metrics:

    MetricRegistry registry = ...; // Get the Codahale's registry
    Metrics metrics = new MetricsBuilder(actorSystem)
        .addProvider(new CodahaleMetricsProvider(actorSystem, registry))
        .build();

The rules for converting gauges, counters, meters, histograms, and timers to gauges for publication also apply for Codahale Metrics.