Add support for per cpu metrics

[dloucasfx]

Signed-off-by: Dani Louca dlouca@splunk.com

Description:
Fixes #5243
With this change, the signalfx exporter is able to emit per core cpu metrics.
The dimension cpu exists for non-aggregated/per_core metrics

Link to tracking Issue:
Fixes #5243

Documentation:

This config example will emit per core and aggregated cpu.interrupt metric

  signalfx:
    access_token: "********"
    api_url: "https://api.us0.signalfx.com"
    ingest_url: "https://ingest.us0.signalfx.com"
    include_metrics:
      - metric_name: "cpu.interrupt"

This config example will emit per core only cpu.interrupt metric

 signalfx:
    access_token: "********"
    api_url: "https://api.us0.signalfx.com"
    ingest_url: "https://ingest.us0.signalfx.com"
    include_metrics:
      - metric_name: "cpu.interrupt"
        dimensions:
          cpu: ["*"]

[dloucasfx]

cc: @mstumpfx

[tigrannajaryan]

The test failed: https://github.com/open-telemetry/opentelemetry-collector-contrib/pull/5756/checks?check_run_id=3899988031

[dmitryax]

Also the issue link (#5243) seems to be wrong, that one is a PR to fix load metrics, not CPU

[dmitryax]

Should we also mention these configuration options to the README?

[dloucasfx]

Also the issue link (#5243) seems to be wrong, that one is a PR to fix load metrics, not CPU

I just referenced it as the request came in from the same user who is trying to accomplish the same task

[dmitryax]

LGTM. It would be nice to have these examples mentioned in the docs

[dloucasfx]

LGTM. It would be nice to have these examples mentioned in the docs

ok, I will add a few

[tigrannajaryan]

@dloucasfx make sure the unit tests pass, they are failing now and it appears it caused by this change.

[rmfitzpatrick]

Do you mind rephrasing with more specificity?

[dloucasfx]

not sure how to be more specific, do you want an example of the datapoints?
This is what the datapoints look like with the config, 3 for cpu.idle ( 2 per core with dim cpu + 1 aggregated) and 2 for cpu.interrupt (2 per core with dim cpu NO aggregated metric)

2021-10-15T01:28:08.397Z	debug	signalfxexporter@v0.36.0/dpclient.go:104	Dispatching SFx datapoint	{"kind": "exporter", "name": "signalfx", "dp": "cpu.idle: intValue:2010766  (Cumulative Counter) 1634261288187\nkey:\"host.name\" value:\"angus-ad.adlab.com\" key:\"os.type\" value:\"LINUX\" key:\"cpu\" value:\"cpu0\" "}
2021-10-15T01:28:08.397Z	debug	signalfxexporter@v0.36.0/dpclient.go:104	Dispatching SFx datapoint	{"kind": "exporter", "name": "signalfx", "dp": "cpu.interrupt: intValue:256  (Cumulative Counter) 1634261288187\nkey:\"host.name\" value:\"angus-ad.adlab.com\" key:\"os.type\" value:\"LINUX\" key:\"cpu\" value:\"cpu0\" "}
2021-10-15T01:28:08.397Z	debug	signalfxexporter@v0.36.0/dpclient.go:104	Dispatching SFx datapoint	{"kind": "exporter", "name": "signalfx", "dp": "cpu.idle: intValue:2010075  (Cumulative Counter) 1634261288187\nkey:\"host.name\" value:\"angus-ad.adlab.com\" key:\"os.type\" value:\"LINUX\" key:\"cpu\" value:\"cpu1\" "}
2021-10-15T01:28:08.397Z	debug	signalfxexporter@v0.36.0/dpclient.go:104	Dispatching SFx datapoint	{"kind": "exporter", "name": "signalfx", "dp": "cpu.interrupt: intValue:523  (Cumulative Counter) 1634261288187\nkey:\"host.name\" value:\"angus-ad.adlab.com\" key:\"os.type\" value:\"LINUX\" key:\"cpu\" value:\"cpu1\" "}
2021-10-15T01:28:08.397Z	debug	signalfxexporter@v0.36.0/dpclient.go:104	Dispatching SFx datapoint	{"kind": "exporter", "name": "signalfx", "dp": "cpu.idle: intValue:4020841  (Cumulative Counter) 1634261288187\nkey:\"host.name\" value:\"angus-ad.adlab.com\" key:\"os.type\" value:\"LINUX\" "}