Construct Prometheus Metrics with ValueType

[KAllan357]

I noticed that on the master branch, you'd see the following information once you were set up with the example:

# HELP example_global_value Example of a top-level global value scrape in the json
# TYPE example_global_value untyped
example_global_value{environment="beta",location="planet-mars"} 1234
# HELP example_value_active Example of sub-level value scrapes from a json
# TYPE example_value_active untyped
example_value_active{environment="beta",id="id-A"} 1
example_value_active{environment="beta",id="id-C"} 1

With this PR, and a corresponding config change to the example like:

---
modules:
  default:
    metrics:
    - name: example_global_value
      path: "{ .counter }"
      help: Example of a top-level global value scrape in the json
      valuetype: gauge
      labels:
        environment: beta # static label
        location: "planet-{.location}"          # dynamic label

    - name: example_value
      type: object
      help: Example of sub-level value scrapes from a json
      path: '{.values[?(@.state == "ACTIVE")]}'
      valuetype: counter
      labels:
        environment: beta # static label
        id: '{.id}'          # dynamic label
      values:
        active: 1      # static value
        count: '{.count}' # dynamic value
        boolean: '{.some_boolean}'
    headers:
      X-Dummy: my-test-header

The # TYPE <metric> <valuetype> ends up correct.

# HELP example_global_value Example of a top-level global value scrape in the json
# TYPE example_global_value gauge
example_global_value{environment="beta",location="planet-mars"} 1234
# HELP example_value_active Example of sub-level value scrapes from a json
# TYPE example_value_active counter
example_value_active{environment="beta",id="id-A"} 1
example_value_active{environment="beta",id="id-C"} 1
# HELP example_value_boolean Example of sub-level value scrapes from a json
# TYPE example_value_boolean counter
example_value_boolean{environment="beta",id="id-A"} 1
example_value_boolean{environment="beta",id="id-C"} 0
# HELP example_value_count Example of sub-level value scrapes from a json
# TYPE example_value_count counter
example_value_count{environment="beta",id="id-A"} 1
example_value_count{environment="beta",id="id-C"} 3

I'm not 100% sure the code for the config.ObjectScrape case is correct - maybe those should default to Untyped?

[SuperQ]

Seems correct, but why are the tests not catching this?

[SuperQ]

Oh, I see, there's no valuetype in the test config.

[SuperQ]

LGTM, I'll follow up with a fix to the tests.