Represent GVK information as labels

Represent GVK information as labels in the metrics, instead of appending
them to the metric name itself. This would allow users to aggregate
varying GVKs of a CR under the same metric, making operations much more
easier.

Author: rexagod

docs/customresourcestate-metrics.md

@@ -48,6 +48,8 @@ spec:
           - --resources=certificatesigningrequests,configmaps,cronjobs,daemonsets,deployments,endpoints,foos,horizontalpodautoscalers,ingresses,jobs,limitranges,mutatingwebhookconfigurations,namespaces,networkpolicies,nodes,persistentvolumeclaims,persistentvolumes,poddisruptionbudgets,pods,replicasets,replicationcontrollers,resourcequotas,secrets,services,statefulsets,storageclasses,validatingwebhookconfigurations,volumeattachments,verticalpodautoscalers
 ```
 
+NOTE: The `group`, `version`, and `kind` common labels are reserved, and will be overwritten by the values from the `groupVersionKind` field.
+
 ### Examples
 
 The examples in this section will use the following custom resource:
@@ -114,7 +116,7 @@ spec:
 Produces the metric:
 
 ```prometheus
-kube_myteam_io_v1_Foo_uptime 43.21
+uptime{group="myteam.io", kind="Foo", version="v1"} 43.21
 ```
 
 #### Multiple Metrics/Kitchen Sink
@@ -165,8 +167,8 @@ spec:
 Produces the following metrics:
 
 ```prometheus
-kube_myteam_io_v1_Foo_active_count{active="1",custom_metric="yes",foo="bar",name="foo",bar="baz",qux="quxx",type="type-a"} 1
-kube_myteam_io_v1_Foo_active_count{active="3",custom_metric="yes",foo="bar",name="foo",bar="baz",qux="quxx",type="type-b"} 3
+active_count{group="myteam.io", kind="Foo", version="v1", active="1",custom_metric="yes",foo="bar",name="foo",bar="baz",qux="quxx",type="type-a"} 1
+active_count{group="myteam.io", kind="Foo", version="v1", active="3",custom_metric="yes",foo="bar",name="foo",bar="baz",qux="quxx",type="type-b"} 3
 ```
 
 ### Metric types
@@ -201,7 +203,7 @@ spec:
 Produces the metric:
 
 ```prometheus
-kube_myteam_io_v1_Foo_uptime 43.21
+uptime{group="myteam.io", kind="Foo", version="v1"} 43.21
 ```
 
 #### StateSet
@@ -227,15 +229,15 @@ spec:
               list: [Pending, Bar, Baz]
 ```
 
-Metrics of type `SateSet` will generate a metric for each value defined in `list` for each resource.
+Metrics of type `StateSet` will generate a metric for each value defined in `list` for each resource.
 The value will be 1, if the value matches the one in list.
 
 Produces the metric:
 
 ```prometheus
-kube_myteam_io_v1_Foo_status_phase{phase="Pending"} 1
-kube_myteam_io_v1_Foo_status_phase{phase="Bar"} 0
-kube_myteam_io_v1_Foo_status_phase{phase="Baz"} 0
+status_phase{group="myteam.io", kind="Foo", version="v1", phase="Pending"} 1
+status_phase{group="myteam.io", kind="Foo", version="v1", phase="Bar"} 0
+status_phase{group="myteam.io", kind="Foo", version="v1", phase="Baz"} 0
 ```
 
 #### Info
@@ -265,7 +267,7 @@ spec:
 Produces the metric:
 
 ```prometheus
-kube_myteam_io_v1_Foo_version{version="v1.2.3"} 1
+version{group="myteam.io", kind="Foo", version="v1", version="v1.2.3"} 1
 ```
 
 ### Naming
@@ -287,7 +289,7 @@ spec:
 
 Produces:
 ```prometheus
-myteam_foos_uptime 43.21
+myteam_foos_uptime{group="myteam.io", kind="Foo", version="v1"} 43.21
 ```
 
 To omit namespace and/or subsystem altogether, set them to the empty string:

pkg/customresourcestate/config.go

@@ -41,9 +41,8 @@ type MetricsSpec struct {
 // Resource configures a custom resource for metric generation.
 type Resource struct {
 	// MetricNamePrefix defines a prefix for all metrics of the resource.
-	// Falls back to the GroupVersionKind string prefixed with "kube_", with invalid characters replaced by _ if nil.
 	// If set to "", no prefix will be added.
-	// Example: If GroupVersionKind is "my-team.io/v1/MyResource", MetricNamePrefix will be "kube_my_team_io_v1_MyResource".
+	// Example: If set to "foo", MetricNamePrefix will be "foo_<metric>".
 	MetricNamePrefix *string `yaml:"metricNamePrefix" json:"metricNamePrefix"`
 
 	// GroupVersionKind of the custom resource to be monitored.
@@ -63,17 +62,11 @@ type Resource struct {
 
 // GetMetricNamePrefix returns the prefix to use for metrics.
 func (r Resource) GetMetricNamePrefix() string {
-	if r.MetricNamePrefix == nil {
-		return strings.NewReplacer(
-			"/", "_",
-			".", "_",
-			"-", "_",
-		).Replace(fmt.Sprintf("kube_%s_%s_%s", r.GroupVersionKind.Group, r.GroupVersionKind.Version, r.GroupVersionKind.Kind))
-	}
-	if *r.MetricNamePrefix == "" {
+	p := r.MetricNamePrefix
+	if p == nil {
 		return ""
 	}
-	return *r.MetricNamePrefix
+	return *p
 }
 
 // GetResourceName returns the lowercase, plural form of the resource Kind. This is ResourcePlural if it is set.

pkg/customresourcestate/registry_factory.go

@@ -34,6 +34,13 @@ import (
 
 func compile(resource Resource) ([]compiledFamily, error) {
 	var families []compiledFamily
+	// Explicitly add GVK labels to all CR metrics.
+	if resource.CommonLabels == nil {
+		resource.CommonLabels = map[string]string{}
+	}
+	resource.CommonLabels["group"] = resource.GroupVersionKind.Group
+	resource.CommonLabels["version"] = resource.GroupVersionKind.Version
+	resource.CommonLabels["kind"] = resource.GroupVersionKind.Kind
 	for _, f := range resource.Metrics {
 		family, err := compileFamily(f, resource)
 		if err != nil {

pkg/customresourcestate/registry_factory_test.go

@@ -324,7 +324,7 @@ func Test_fullName(t *testing.T) {
 				resource: r(nil),
 				f:        count,
 			},
-			want: "kube_apps_v1_Deployment_count",
+			want: "count",
 		},
 		{
 			name: "no prefix",