Adds Support for Cross-Namespace Metrics

pkg/config/config.go

@@ -38,6 +38,9 @@ type DiscoveryRule struct {
 	// `.GroupBy` is the comma-separated expected group-by label names. The delimeters
 	// are `<<` and `>>`.
 	MetricsQuery string `yaml:"metricsQuery,omitempty"`
+	// Options specifies additional parameters that are taken into account
+	// when configuring a rule. These can be used to fine-tune the retrieval of metrics
+	Options Options `yaml:"options,omitempty"`
 }
 
 // RegexFilter is a filter that matches positively or negatively against a regex.
@@ -80,6 +83,13 @@ type NameMapping struct {
 	As string `yaml:"as"`
 }
 
+// Option describes a set of customisations for retrieving metrics
+type Options struct {
+	// option to allow cross-namespace metrics. Used to determine whether to
+	// append the namespace as a label selector when retrieving metrics
+	DetatchFromNamespace bool `yaml:"detachFromNamespace,omitempty"`
+}
+
 // ResourceRules describe the rules for querying resource metrics
 // API results.  It's assumed that the same metrics can be used
 // to aggregate across different resources.

pkg/naming/metric_namer.go

@@ -104,6 +104,8 @@ type metricNamer struct {
 	seriesMatchers []*ReMatcher
 
 	ResourceConverter
+
+	options config.Options
 }
 
 // queryTemplateArgs are the arguments for the metrics query template.
@@ -133,7 +135,7 @@ func (n *metricNamer) QueryForSeries(series string, resource schema.GroupResourc
 func (n *metricNamer) QueryForExternalSeries(series string, namespace string, metricSelector labels.Selector) (prom.Selector, error) {
 	//test := prom.Selector()
 	//return test, nil
-	return n.metricsQuery.BuildExternal(series, namespace, "", []string{}, metricSelector)
+	return n.metricsQuery.BuildExternal(series, namespace, "", []string{}, metricSelector, n.options)
 }
 
 func (n *metricNamer) MetricNameForSeries(series prom.Series) (string, error) {
@@ -208,6 +210,7 @@ func NamersFromConfig(cfg []config.DiscoveryRule, mapper apimeta.RESTMapper) ([]
 			nameAs:            nameAs,
 			seriesMatchers:    seriesMatchers,
 			ResourceConverter: resConv,
+			options:           rule.Options,
 		}
 
 		namers[i] = namer

pkg/naming/metrics_query.go

@@ -28,6 +28,7 @@ import (
 	"k8s.io/apimachinery/pkg/selection"
 
 	prom "github.com/directxman12/k8s-prometheus-adapter/pkg/client"
+	"github.com/directxman12/k8s-prometheus-adapter/pkg/config"
 )
 
 // MetricsQuery represents a compiled metrics query for some set of
@@ -40,7 +41,7 @@ type MetricsQuery interface {
 	// where we need to scope down more specifically than just the group-resource
 	// (e.g. container metrics).
 	Build(series string, groupRes schema.GroupResource, namespace string, extraGroupBy []string, resourceNames ...string) (prom.Selector, error)
-	BuildExternal(seriesName string, namespace string, groupBy string, groupBySlice []string, metricSelector labels.Selector) (prom.Selector, error)
+	BuildExternal(seriesName string, namespace string, groupBy string, groupBySlice []string, metricSelector labels.Selector, options config.Options) (prom.Selector, error)
 }
 
 // NewMetricsQuery constructs a new MetricsQuery by compiling the given Go template.
@@ -136,13 +137,13 @@ func (q *metricsQuery) Build(series string, resource schema.GroupResource, names
 	return prom.Selector(queryBuff.String()), nil
 }
 
-func (q *metricsQuery) BuildExternal(seriesName string, namespace string, groupBy string, groupBySlice []string, metricSelector labels.Selector) (prom.Selector, error) {
+func (q *metricsQuery) BuildExternal(seriesName string, namespace string, groupBy string, groupBySlice []string, metricSelector labels.Selector, options config.Options) (prom.Selector, error) {
 	queryParts := []queryPart{}
 
 	// Build up the query parts from the selector.
 	queryParts = append(queryParts, q.createQueryPartsFromSelector(metricSelector)...)
 
-	if namespace != "" {
+	if namespace != "" && options.DetatchFromNamespace != true {
 		namespaceLbl, err := q.resConverter.LabelForResource(NsGroupResource)
 		if err != nil {
 			return "", err

pkg/naming/metrics_query_test.go

@@ -21,6 +21,7 @@ import (
 	"testing"
 
 	prom "github.com/directxman12/k8s-prometheus-adapter/pkg/client"
+	"github.com/directxman12/k8s-prometheus-adapter/pkg/config"
 	pmodel "github.com/prometheus/common/model"
 	labels "k8s.io/apimachinery/pkg/labels"
 	"k8s.io/apimachinery/pkg/runtime/schema"
@@ -261,6 +262,7 @@ func TestBuildExternalSelector(t *testing.T) {
 		groupBy        string
 		groupBySlice   []string
 		metricSelector labels.Selector
+		options        config.Options
 
 		check checkFunc
 	}{
@@ -340,6 +342,36 @@ func TestBuildExternalSelector(t *testing.T) {
 				hasSelector(`foo="bar",namespaces="default"`),
 			),
 		},
+		{
+			name: "single LabelMatchers value with namespace - detached namespace",
+
+			mq:        mustNewQuery(`<<.LabelMatchers>>`),
+			namespace: "default",
+			options:   config.Options{DetatchFromNamespace: true},
+			metricSelector: labels.NewSelector().Add(
+				*mustNewLabelRequirement("foo", selection.Equals, []string{"bar"}),
+			),
+
+			check: checks(
+				hasError(nil),
+				hasSelector(`foo="bar"`),
+			),
+		},
+		{
+			name: "single LabelMatchers value with namespace - explicit attached namespace",
+
+			mq:        mustNewQuery(`<<.LabelMatchers>>`),
+			namespace: "default",
+			options:   config.Options{DetatchFromNamespace: false},
+			metricSelector: labels.NewSelector().Add(
+				*mustNewLabelRequirement("foo", selection.Equals, []string{"bar"}),
+			),
+
+			check: checks(
+				hasError(nil),
+				hasSelector(`foo="bar",namespaces="default"`),
+			),
+		},
 		{
 			name: "multiple LabelMatchers value",
 
@@ -384,7 +416,7 @@ func TestBuildExternalSelector(t *testing.T) {
 
 	for _, tc := range tests {
 		t.Run(tc.name, func(t *testing.T) {
-			selector, err := tc.mq.BuildExternal(tc.series, tc.namespace, tc.groupBy, tc.groupBySlice, tc.metricSelector)
+			selector, err := tc.mq.BuildExternal(tc.series, tc.namespace, tc.groupBy, tc.groupBySlice, tc.metricSelector, tc.options)
 			t.Logf("selector: '%v'", selector)
 
 			if err := tc.check(selector, err); err != nil {