New component: receiver/expvarreceiver

[jamesmoessis]

The purpose and use-cases of the new component

An Expvar Receiver scrapes metrics from expvar, which exposes data in JSON format from an HTTP endpoint. The metrics are extracted from the expvar variable memstats, which exposes various information about the Go runtime.

Example configuration for the component

In the past we've used the signalfx-agent's expvar monitor, and I feel like this receiver could expose similar configurations.

We can also take inspiration from the hostmetricsreceiver which provides a set of default metrics, while allowing metrics to be included/excluded.

An example config could look like:

expvar:
  collection_interval: 30s
  host: 0.0.0.0
  port: 10000
  https: false
  path: /debug/vars 
  metrics: 
    <metric_name>:
      enabled: <true|false>

Telemetry data types supported

Metrics only.

Sponsor (Optional)

Looking for a sponsor 😃

Open to any suggestions and advice!

[MovieStoreGuy]

I am happy to sponsor this

[jamesmoessis]

This is now complete and in the contrib build