Fix: pass-through to runtime overrides for FilterPolicies and TargetInfoExcludedDimensions

[electron0zero]

What this PR does:

When userconfigurableoverrides are enabled, we were returning metrics_generator filter_policies as empty even when it's set in per tenant runtime overrides.

This is a bug, we should return per tenant runtime overides when filter_policies are not set at userconfigurableoverrides.

this PR added a len > 0 check to fix this for multiple attribuets, and adds a test for all overrides when userconfigurableoverrides is enabled.

Which issue(s) this PR fixes:
Fixes #

Checklist

• Tests updated
• Documentation added
• CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX]

[yvrhdn]

this PR added a len > 0 check to fix this for multiple attributes, and adds a test for all overrides when userconfigurableoverrides is enabled.

This is actually intentional in the API: if you set an override to [] you are explicitly setting it to an empty list and it should take priority over overrides set in the configmap.

So if you pass this to the API:

{
  "metrics_generator": {
    "processor": {
      "service_graphs": {
        "peer_attributes": []
      }
    }
  }
}

And the configmap has:

{
  "metrics_generator": {
    "processor": {
      "service_graphs": {
        "peer_attributes": ["db.name", "db.system", "db.url"]
      }
    }
  }
}

The merged result should be:

{
  "metrics_generator": {
    "processor": {
      "service_graphs": {
        "peer_attributes": []
      }
    }
  }
}

PeerAttributes is a *[]string to allows us to distinguish between "empty list" and "not set".

tempo/modules/overrides/userconfigurable/client/limits.go

Line 88 in 67fd171

PeerAttributes *[]string `json:"peer_attributes,omitempty"`

[electron0zero]

this PR added a len > 0 check to fix this for multiple attributes, and adds a test for all overrides when userconfigurableoverrides is enabled.

This is actually intentional in the API: if you set an override to [] you are explicitly setting it to an empty list and it should take priority over overrides set in the configmap.

So if you pass this to the API:

{
  "metrics_generator": {
    "processor": {
      "service_graphs": {
        "peer_attributes": []
      }
    }
  }
}

And the configmap has:

{
  "metrics_generator": {
    "processor": {
      "service_graphs": {
        "peer_attributes": ["db.name", "db.system", "db.url"]
      }
    }
  }
}

The merged result should be:

{
  "metrics_generator": {
    "processor": {
      "service_graphs": {
        "peer_attributes": []
      }
    }
  }
}

PeerAttributes is a *[]string to allows us to distinguish between "empty list" and "not set".

tempo/modules/overrides/userconfigurable/client/limits.go

Line 88 in 67fd171

PeerAttributes *[]string `json:"peer_attributes,omitempty"`

makes sense, I was not aware of this. looks like this is not the bug, and but is in the pass through code. updated the fix now.

[electron0zero]

this was the bug, it was incorrectly retuning true for FilterPolicies and TargetInfoExcludedDimensions