File based task/template/handler definition

This proposal introduces directory based task, template, and handler definition.

Configuration

The load service configuration is specified under the load tag of the kapacitor configuration file.

[load]
 enabled = true
 dir="/path/to/directory"

dir specifies the directory where the definition files exist.

The service will attempt to load data from three subdirectories.

The tasks directory should contain task tickscripts and and the associated templated task definition files (either yaml or json).

The templates directory should contain templated tickscripts.

The handlers directory will contain will contain topic handler definitions in yaml or json.

Tasks

Task files must be placed in the tasks subdirectory of the load service directory. Defining tasks explicitly will be done according to the following scheme:

• id - the file name without the tick extension
• type - determined by introspection of the task (stream, batch)
• dbrp - defined using the dbrp keyword followed by a specified database and retention policy

For example, the tickscript

// /path/to/directory/tasks/my_task.tick
dbrp "telegraf"."autogen"

stream
    |from()
        .measurement('cpu')
        .groupBy(*)
    |alert()
        .warn(lambda: "usage_idle" < 20)
        .crit(lambda: "usage_idle" < 10)
        // Send alerts to the `cpu` topic
        .topic('cpu')

will create a stream task named my_task for the dbrp telegraf.autogen.

Templates

Template files must be placed in the templates subdirectory of the load service directory. Defining templated tasks is done according to the following scheme:

• id - the file name without the tick extension
• type - determined by introspection of the task (stream, batch)
• dbrp - defined using the dbrp keyword followed by a specified database and retention policy

For example, the tickscript

// /path/to/directory/templates/my_template.tick
dbrp "telegraf"."autogen"

var measurement string
var where_filter = lambda: TRUE
var groups = [*]
var field string
var warn lambda
var crit lambda
var window = 5m
var slack_channel = '#alerts'

stream
    |from()
        .measurement(measurement)
        .where(where_filter)
        .groupBy(groups)
    |window()
        .period(window)
        .every(window)
    |mean(field)
    |alert()
         .warn(warn)
         .crit(crit)
         .slack()
         .channel(slack_channel)

will create a stream template named my_template for the dbrp telegaf.autogen.

Templated Tasks

Templated task files must be placed in the tasks subdirectory of the load service directory. Defining templated tasks will be done according to the following scheme:

• id - filename without the yaml, yml, or json extension
• dbrps - required if not specified in template
• template-id - required
• vars - list of template vars

For example, the templated task file

# /path/to/directory/tasks/my_templated_tas.tick
dbrps:
  - { db: "telegraf", rp: "autogen"}
template-id: my_template
vars:
  measurement:
   type: string
   value: cpu
  where_filter:
   type: lambda
   value: "\"cpu\" == 'cpu-total'"
  groups:
   type: list
   value:
       - type: string
         value: host
       - type: string
         value: dc
  field:
   type: string
   value : usage_idle
  warn:
   type: lambda
   value: "\"mean\" < 30.0"
  crit:
   type: lambda
   value: "\"mean\" < 10.0"
  window:
   type: duration
   value : 1m
  slack_channel:
   type: string
   value: "#alerts_testing"

will create a stream task named my_templated_task for the dbrp telegraf.autogen.

The same task may be created using JSON like so:

{
  "dbrps": [{"db": "telegraf", "rp": "autogen"}],
  "template-id": "my_template",
  "vars": {
    "measurement": {"type" : "string", "value" : "cpu" },
    "where_filter": {"type": "lambda", "value": "\"cpu\" == 'cpu-total'"},
    "groups": {"type": "list", "value": [{"type":"string", "value":"host"},{"type":"string", "value":"dc"}]},
    "field": {"type" : "string", "value" : "usage_idle" },
    "warn": {"type" : "lambda", "value" : "\"mean\" < 30.0" },
    "crit": {"type" : "lambda", "value" : "\"mean\" < 10.0" },
    "window": {"type" : "duration", "value" : "1m" },
    "slack_channel": {"type" : "string", "value" : "#alerts_testing" }
  }
}

Handlers

Topic Handler files must be placed in the handlers subdirectory of the load service directory.

id: hanlder-id
topic: cpu
kind: slack
match: changed() == TRUE
options:
  channel: '#alerts'