feat: Append existing Pod labels to all Pod related metrics

Author: alen-z

docs/cli-arguments.md

@@ -56,6 +56,7 @@ Flags:
       --metric-annotations-allowlist string        Comma-separated list of Kubernetes annotations keys that will be used in the resource' labels metric. By default the metric contains only name and namespace labels. To include additional annotations provide a list of resource names in their plural form and Kubernetes annotation keys you would like to allow for them (Example: '=namespaces=[kubernetes.io/team,...],pods=[kubernetes.io/team],...)'. A single '*' can be provided per resource instead to allow any annotations, but that has severe performance implications (Example: '=pods=[*]').
       --metric-denylist string                     Comma-separated list of metrics not to be enabled. This list comprises of exact metric names and/or regex patterns. The allowlist and denylist are mutually exclusive.
       --metric-labels-allowlist string             Comma-separated list of additional Kubernetes label keys that will be used in the resource' labels metric. By default the metric contains only name and namespace labels. To include additional labels provide a list of resource names in their plural form and Kubernetes label keys you would like to allow for them (Example: '=namespaces=[k8s-label-1,k8s-label-n,...],pods=[app],...)'. A single '*' can be provided per resource instead to allow any labels, but that has severe performance implications (Example: '=pods=[*]'). Additionally, an asterisk (*) can be provided as a key, which will resolve to all resources, i.e., assuming '--resources=deployments,pods', '=*=[*]' will resolve to '=deployments=[*],pods=[*]'.
+      --metric-labels-append string                Comma-separated list of additional Kubernetes label keys that will be added with their corresponding values to all metrics. By default the metric contains only name and namespace labels. Use of regex is supported (Example: '=regex=meta.example.com/(.*),product').
       --metric-opt-in-list string                  Comma-separated list of metrics which are opt-in and not enabled by default. This is in addition to the metric allow- and denylists
       --namespaces string                          Comma-separated list of namespaces to be enabled. Defaults to ""
       --namespaces-denylist string                 Comma-separated list of namespaces not to be enabled. If namespaces and namespaces-denylist are both set, only namespaces that are excluded in namespaces-denylist will be used.

internal/store/builder.go

@@ -85,6 +85,7 @@ type Builder struct {
 	buildCustomResourceStoresFunc ksmtypes.BuildCustomResourceStoresFunc
 	allowAnnotationsList          map[string][]string
 	allowLabelsList               map[string][]string
+	appendLabelsList              string
 	useAPIServerCache             bool
 	utilOptions                   *options.Options
 }
@@ -455,7 +456,8 @@ func (b *Builder) buildStorageClassStores() []cache.Store {
 }
 
 func (b *Builder) buildPodStores() []cache.Store {
-	return b.buildStoresFunc(podMetricFamilies(b.allowAnnotationsList["pods"], b.allowLabelsList["pods"]), &v1.Pod{}, createPodListWatch, b.useAPIServerCache)
+	b.appendLabelsList = b.utilOptions.LabelsAppend
+	return b.buildStoresFunc(podMetricFamilies(b.allowAnnotationsList["pods"], b.allowLabelsList["pods"], b.appendLabelsList), &v1.Pod{}, createPodListWatch, b.useAPIServerCache)
 }
 
 func (b *Builder) buildCsrStores() []cache.Store {