CustomResourceStateMetrics Wildcard in paths

[codysmithd]

What would you like to be added:
Ability to wildcard parts of paths for CustomResourceStateMetrics, in this case specifically a StateSet path, but could equally apply to other paths.

Example:

Custom Resource

status:
    foos:
    - name: "a"
      conditions:
      - type: "MetricForThis"
        color: "green"
    - name: "b"
    - name: "c" 
      conditions:
      - type: "MetricForThis"
        color: "yellow" 

We want to report a StateSet metric for the color of foos that have a condition of type "MetricForThis".

Config

metrics:
  - name: my_metric
    each:
      type: StateSet
    stateSet:
      labelName: color
      path: [status, foos, "[name=*]", "conditions", "[type=MetricForThis]", color]
      list: [green, yellow, red]

[name=*] means "any" name where the following path conditions still apply. To differentiate matching instances, the value of the wildcard is also applied as a label.

Metric output

my_metric{name="a", color="green"} 1
my_metric{name="a", color="yellow"} 0
my_metric{name="a", color="red"} 0

my_metric{name="c", color="green"} 0
my_metric{name="c", color="yellow"} 1
my_metric{name="c", color="red"} 0

Outside of the basic case presented here, ideally this would work with further levels nesting as well (multiple wildcards in the path).

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[CatherineF-dev]

Will it be covered by #1978?

Or you would like [status, foos, "[name=*]", "conditions", "[type=MetricForThis]", color] instead writing cel to extract these fields?

[logicalhan]

I think we should cover this by CEL.

[codysmithd]

Agreed, thank you!