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Streaming plugins use grpc streams to allow the plugin to send data immediately or after a certain period of time instead of on an interval governed by Snap. Streaming by snap enables -

  • Improved performance by enabling event based data flows
  • Runtime configuration controlling event throughput
  • Buffer configurations which dispatch events after a given duration and/or when a given event count has been reached

Currently there are two plugins that support streaming - snap relay and snap-plugin-collector-rand-streaming.

Configuration options

MaxCollectDuration and MaxMetricsBuffer are two configuration options that can be set through streaming task manifest or flags.

  • MaxCollectDuration sets the maximum duration between collections before metrics are sent. It is always greater than 0 and defaults to 10s which means that after 10 seconds if no new metrics are received, the plugin should send whatever data it has in the buffer.
  • MaxMetricsBuffer is the maximum number of metrics the plugin is buffering before sending metrics. It defaults to 0 which means the metrics are sent immediately.

Streaming task schedule

  version: 1
    type: "streaming"
        /random/integer: {}
          MaxCollectDuration: "6s"
          MaxMetricsBuffer: 600

Streaming configuration flags

Below is an example of the how to run the snap-relay using the configurable flags.

  1. Start the Snap daemon:
  • Run
$ snapteld -l 1 -t 0

The option "-l 1" is for setting the debugging log level and "-t 0" is for disabling plugin signing.

  1. Start the relay using flags:
  • Run snap-relay plugin
$ go run main.go --stand-alone --stand-alone-port 8182 --log-level 5 --max-collect-duration 10s --max-metrics-buffer 50

Output: Preamble URL: [::]:8182
  1. Obtain meta information:
  • Curl preamble
$ curl localhost:8182
  1. Start client in snap-relay:
  • Run client (from a different terminal) using the listen address obtained from the previous step
$ go run client/main.go
  1. Load plugin:
$ snaptel plugin load http://localhost:8182
Plugin loaded
Name: plugin-relay
Version: 1
Type: streaming-collector
Signed: false
Loaded Time: Tue, 05 Sep 2017 17:41:42 PDT
  • List the metric catalog by running:
$ snaptel metric list
/intel/relay/collectd 	           1
/intel/relay/statsd 	           1
  1. Create a task manifest for snap-relay (see exemplary files):
  version: 1
    type: "streaming"
       /intel/relay/collectd: {}
  1. Create a task:
$ snaptel task create -t collectd.yaml
Using task manifest to create task
Task created
ID: c168b992-8aaf-4eec-8e3c-883510962789
Name: Task-c168b992-8aaf-4eec-8e3c-883510962789
State: Running

Metrics exposed by streaming collectors

Below are some of the metrics collected by the streaming plugins currently:

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