Cloudwatch scaler - Support cloudwatch metrics with multiple dimensions

[jmhoeft]

Support cloudwatch metrics with multiple dimensions

Use-Case

Right now the cloudwatch scaler only lets you specify a single dimension name and value. This means you can't scale on any metrics with multiple dimensions.

Specification

It would be great to be able to specify a list of dimensions in the ScaleTrigger:

- type: aws-cloudwatch
  metadata:
    # Required: namespace
    namespace: MyCustomNamespace
    # Required: At least one dimension name
    dimensions:
    - Name: QueueName
      Value: keda
    - Name: env
      Value: dev
    metricName: AGE
    targetMetricValue: "2"
    minMetricValue: "0"
    ...

[jmhoeft]

The cloudwatch GetMetricData call definitely supports multiple dimensions on the metric, the limiting factor here is the ScaleTriggers Metadata being map[string]string. I already did some work to prove this out but wanted to hear if you folks had any thoughts on how to implement this.

[JonasMatos0]

Got confirmation that this is a good feature to be implemented.
#1321

I'm taking a look on the needed changes. If you want to collaborate yourself, please let me know what you have so far, @jmhoeft .

[jmhoeft]

Hey! Somehow just saw this. Let me remember what I was doing and get it pushed soon. Basically, what I was unsure about was that this call works just fine with multiple dimensions, but I wasn't sure the best way to get the inputs. It will probably require changes to CRDs.

[JonasMatos0]

@jmhoeft solution merged on
#1517
kedacore/keda-docs#352