Custom Output Source

telem.output.custom (func: fun(collection: MetricCollection))

Wraps a user-provided function for custom output implementations. Need to write out metrics to a file? Toggle redstone lamps when a threshold is reached? Update a custom GUI dashboard? Anything is possible!

The provided function is used as a metric consumer. Internally, func is called with one argument, collection, which is the MetricCollection created by the Backplane during a cycle.

• v0.2.0 and newer:

  Name	Type	Default
  func	fun(collection: MetricCollection)	nil
  Function executed when writing to this output adapter

• v0.1.0:

  Name	Type	Default
  func	fun(metrics: Metric[], context: table)	nil
  Function executed when writing to this output adapter

Usage

local telem = require 'telem'

local backplane = telem.backplane()
  :addInput('hello_in', telem.input.helloWorld(123))
  :addInput('custom_long', telem.input.custom(function ()
    return
      telem.metric('custom_long_1', 456),
      telem.metric('custom_long_2', 503.123),
      telem.metric{
        name = 'custom_long_detail',
        value = math.random(),
        unit = 'randoms',
        source = 'lua:math.random'
      }
  end))
  :addOutput('custom_out', telem.output.custom(function (collection)
    for _,v in pairs(collection.metrics) do
      print('% ', v)
    end
  end))
  :cycleEvery(1)()

Behavior

The example usage will produce the following output every cycle:

%  custom_long_1 = 456 from custom_long
%  custom_long_2 = 503.123 from custom_long
%  custom_long_detail = 0.872219000824 randoms from custom_long (lua:math.random)
%  hello_world = 123 from hello_in