Some more adjustment.

* Breaking out some types to make the functionality more composable and easier to digest. (e.g. `basicMetricLister` interacts with Prometheus and `periodicMetricLister` periodically invokes `basicMetricLister`.
* Pulling out some of the type embedding between `basicSeriesRegistry` and `MetricLister` to make it easier to digest.
* Deleting the `/metric-converter` code because I'm pretty certain it's not going to be necessary as things transition to using the namer-based configuration.
* Some light-ish refactoring in `metricNamer` to get some re-use out of query generation in preparation for using it with external metrics.

pkg/custom-provider/metric-converter/vector_converter.go

@@ -1,58 +0,0 @@
-package provider
-
-import (
-	"errors"
-
-	prom "github.com/directxman12/k8s-prometheus-adapter/pkg/client"
-	"github.com/prometheus/common/model"
-	"k8s.io/metrics/pkg/apis/external_metrics"
-)
-
-type vectorConverter struct {
-	SampleConverter SampleConverter
-}
-
-//NewVectorConverter creates a VectorConverter capable of converting
-//vector Prometheus query results into external metric types.
-func NewVectorConverter(sampleConverter *SampleConverter) MetricConverter {
-	return &vectorConverter{
-		SampleConverter: *sampleConverter,
-	}
-}
-
-func (c *vectorConverter) Convert(metadata QueryMetadata, queryResult prom.QueryResult) (*external_metrics.ExternalMetricValueList, error) {
-	if queryResult.Type != model.ValVector {
-		return nil, errors.New("vectorConverter can only convert scalar query results")
-	}
-
-	toConvert := *queryResult.Vector
-
-	if toConvert == nil {
-		return nil, errors.New("the provided input did not contain vector query results")
-	}
-
-	return c.convert(metadata, toConvert)
-}
-
-func (c *vectorConverter) convert(metadata QueryMetadata, result model.Vector) (*external_metrics.ExternalMetricValueList, error) {
-	items := []external_metrics.ExternalMetricValue{}
-	metricValueList := external_metrics.ExternalMetricValueList{
-		Items: items,
-	}
-
-	numSamples := result.Len()
-	if numSamples == 0 {
-		return &metricValueList, nil
-	}
-
-	for _, val := range result {
-		//TODO: Care about potential errors here.
-		singleMetric, _ := c.SampleConverter.Convert(metadata, val)
-		items = append(items, *singleMetric)
-	}
-
-	metricValueList = external_metrics.ExternalMetricValueList{
-		Items: items,
-	}
-	return &metricValueList, nil
-}