enhancement: relax kube_.+_created to allow namespaces

Signed-off-by: Pranshu Srivastava <rexagod@gmail.com>

Author: rexagod

docs/customizations/kube-state-metrics-custom-denylist.md

@@ -0,0 +1,27 @@
+### Supplying a custom deny-list to Kube State Metrics (KSM)
+
+Users can supply their own custom deny-list that replaces the default one and filters out the specified metrics from being generated by KSM.
+
+The following example shows how to supply a custom deny-list:
+
+```yaml mdox-exec="cat examples/jsonnet-snippets/kube-state-metrics-custom-denylist.jsonnet"
+(import 'kube-prometheus/addons/ksm-lite.libsonnet') {
+  ksmConfig: {
+    ksmDenyList: [
+      '^kube_(?=namespace).*_created$',
+      '^kube_.+_metadata_resource_version$',
+      '^kube_replicaset_metadata_generation$',
+      '^kube_replicaset_status_observed_generation$',
+      '^kube_pod_restart_policy$',
+      '^kube_pod_init_container_status_terminated$',
+      '^kube_pod_init_container_status_running$',
+      '^kube_pod_container_status_terminated$',
+      '^kube_pod_container_status_running$',
+      '^kube_pod_completion_time$',
+      '^kube_pod_status_scheduled$',
+    ],
+  },
+}
+```
+
+The example above makes use of a [feature](https://github.com/kubernetes/kube-state-metrics/pull/2616) introduced in the v2.16.0 release of KSM, which allows users to utilize lookarounds within regular expressions. As such, it keeps almost all of the default deny-list, but filters out only the `kube_namespace_created` metric allowing that to be generated.

examples/jsonnet-snippets/kube-state-metrics-custom-denylist.jsonnet

@@ -0,0 +1,17 @@
+(import 'kube-prometheus/addons/ksm-lite.libsonnet') {
+  ksmConfig: {
+    ksmDenyList: [
+      '^kube_(?=namespace).*_created$',
+      '^kube_.+_metadata_resource_version$',
+      '^kube_replicaset_metadata_generation$',
+      '^kube_replicaset_status_observed_generation$',
+      '^kube_pod_restart_policy$',
+      '^kube_pod_init_container_status_terminated$',
+      '^kube_pod_init_container_status_running$',
+      '^kube_pod_container_status_terminated$',
+      '^kube_pod_container_status_running$',
+      '^kube_pod_completion_time$',
+      '^kube_pod_status_scheduled$',
+    ],
+  },
+}

jsonnet/kube-prometheus/addons/ksm-lite.libsonnet

@@ -1,33 +1,39 @@
-local addArgs(args, name, containers) = std.map(
-  function(c) if c.name == name then
-    c {
-      args+: args,
-    }
-  else c,
-  containers,
-);
+local addArgs(args, name, containers) =
+  std.map(
+    function(c)
+      if c.name == name then
+        c {
+          args+: args,
+        }
+      else
+        c,
+    containers,
+  );
 
 {
+  ksmConfig+:: {
+    ksmDenyList: [
+      '^kube_.+_created$',
+      '^kube_.+_metadata_resource_version$',
+      '^kube_replicaset_metadata_generation$',
+      '^kube_replicaset_status_observed_generation$',
+      '^kube_pod_restart_policy$',
+      '^kube_pod_init_container_status_terminated$',
+      '^kube_pod_init_container_status_running$',
+      '^kube_pod_container_status_terminated$',
+      '^kube_pod_container_status_running$',
+      '^kube_pod_completion_time$',
+      '^kube_pod_status_scheduled$',
+    ],
+  },
+
   kubeStateMetrics+: {
     deployment+: {
       spec+: {
         template+: {
           spec+: {
             containers: addArgs(
-              [|||
-                --metric-denylist=
-                ^kube_.+_created$,
-                ^kube_.+_metadata_resource_version$,
-                ^kube_replicaset_metadata_generation$,
-                ^kube_replicaset_status_observed_generation$,
-                ^kube_pod_restart_policy$,
-                ^kube_pod_init_container_status_terminated$,
-                ^kube_pod_init_container_status_running$,
-                ^kube_pod_container_status_terminated$,
-                ^kube_pod_container_status_running$,
-                ^kube_pod_completion_time$,
-                ^kube_pod_status_scheduled$
-              |||],
+              ['--metric-denylist=\n' + std.join(',\n', $.ksmConfig.ksmDenyList) + '\n'],
               'kube-state-metrics',
               super.containers
             ),