Godot is a streaming real-time event processor based on Riemann written in Node.js

• Usage
• Events
• Reactors
  • Primitives
• Producers
• Tests

Here is a simple example of a Reactor server that will send an email to user@host.com if the Producer server for app.server fails to send a heartbeat after 60 seconds.

  var godot = require('../lib/godot');

  //
  // Reactor server which will email `user@host.com`
  // whenever any service matching /.*\/health\/heartbeat/
  // fails to check in after 60 seconds.
  //
  godot.createServer({
    //
    // Defaults to UDP
    //
    type: 'udp',
    reactors: [
      godot.reactor()
        .where('service', '*/health/heartbeat')
        .expire(1000 * 60)
        .email({ to: 'user@host.com' })
    ]
  }).listen(1337);

  //
  // Producer client which sends events for the service
  // `app.server/health/heartbeat` every 15 seconds.
  //
  godot.createClient({
    //
    // Defaults to UDP
    //
    type: 'udp',
    producers: [
      godot.producer({
        host: 'app.server.com',
        service: 'app.server/health/heartbeat',
        ttl: 1000 * 15
      })
    ],
    //
    // Add Reconnect logic that uses node-backoff
    //
    reconnect: {
      type: 'exponential',
      maxTries: 2,
      initialDelay: 100,
      maxDelay: 300
    }
  }).connect(1337);

Similar to Riemann, events in godot are simply JSON sent over UDP or TCP. Each event has these optional fields:

  {
    host:         "A hostname, e.g. 'api1', 'foo.com'"
    service:      "e.g. 'API port 8000 reqs/sec'",
    state:        "Any string less than 255 bytes, e.g. 'ok', 'warning', 'critical'",
    time:         "The time of the event, in unix epoch seconds",
    description:  "Freeform text",
    tags:         "Freeform list of strings, e.g. ['rate', 'fooproduct', 'transient']",
    meta:         "Freeform set of key:value pairs e.g. { 'ewma': 12345 }",
    metric:       "A number associated with this event, e.g. the number of reqs/sec.",
    ttl:          "A floating-point time, in seconds, that this event is considered valid for."
  }

Reactors in Godot are readable and writable Stream instances which consume Events and produce actions or aggregate data flow.

There are several core Reactor primitives available in godot which can be composed to create more complex behavior:

• .aggregate(): Aggregates metric property on events
• .change(key {from: x, to: y}): Emits events when the key is changed, accepts optional from and to options for more specific changes.
• .email(options): Sends an email to the specified options.
• .expire(ttl): Emits an event when no data is received after ttl milliseconds.
• .forward(options): Forwards all events to a remote server located at options.host and options.port.
• .sms(options): Sends an sms to the specified options.
• .where(key, value)|.where(filters): Filters events based on a single key:value pair or a set of key:value filters.
• .rollup(interval, limit)|.rollup(options): Rollup a limit amount of events to emit every interval. interval can also be a function to allow you to create varying intervals (see docs).
• .by(key|[key0, key1...], reactor): Creates a new godot reactor stream for each unique value for the key or keys passed into it.
• .around(reactor0, reactor1, ...): Pipe the same stream of data to independent reactor streams
• .console()|.console(formatFn): output the data with console.dir or do custom output with a formatFn that takes data as an argument
• .meta(key, reactor): assigns a value to data.meta[key] to the data coming through the stream based on the metric value of the reactor given as the second argument.
• .sum(): Sum the data.metric value of the events as they come through the pipe stream.
• .over(ceiling): Emits an event when data.metric is > ceiling
• .within(min, max): Emits an event when data.metric is within the given inclusive range of {min, max}
• .movingAverage({average: 'type', window: window}): Calculate various types of moving averages over a defined event or time window.
• `.windowSum(window): Calculates the sum of metrics over a given event or time window
• .redis(options, redisFn): Returns a redis client with data and callback to the redisFn to be used for redis operations to occur on each event.

Producers in Godot are readable Stream instances which produce Events. Events will be emitted by a given Producer every ttl milliseconds.

All tests are written in vows and can be run with npm:

  npm test