aggregator.lua

local aggregator = {}

local count = 0;

function aggregator.init()
  count = 0
end

function aggregator.process()
  count = count + 1
end

function aggregator.timer_handler(emit)
  emit(make_counter(count))
  count = 0
end

function aggregator.shutdown(emit)
  emit(make_counter(count))
end

function make_counter(value)
  return {
    metric = {
      name = "event_counter",
      kind = "incremental",
      timestamp = os.date("!*t"),
      counter = {
        value = value
      }
    }
  }
end

return aggregator

vector.toml

[sources.in]
type = "stdin"

[transforms.aggregator]
type = "lua"
version = "2"
inputs = ["in"] # add names of the input components here
hooks.init = "aggregator.init"
hooks.process = "aggregator.process"
hooks.shutdown = "aggregator.shutdown"
timers = [{interval_seconds = 1, handler = "aggregator.timer_handler"}]
source = "aggregator = require('aggregator')"

[sinks.out]
type = "console"
inputs = ["aggregator"]
encoding.codec = "json"