s/kube_node_info/kube_node_role

Use kube_node_role{role="control-plane"} (see [1] and [2]) to estimate if the cluster is HA or not.
* [1]: https://github.com/search?q=repo%3Akubernetes%2Fkube-state-metrics%20kube_node_role&type=code
* [2]: https://kubernetes.io/docs/reference/labels-annotations-taints/#node-role-kubernetes-io-control-plane

Also drop any thresholds as they would lead to false positives.

Author: rexagod

alerts/resource_alerts.libsonnet

@@ -37,9 +37,9 @@ local utils = import '../lib/utils.libsonnet';
           if $._config.showMultiCluster then {
             expr: |||
               (sum(namespace_cpu:kube_pod_container_resource_requests:sum{%(ignoringOverprovisionedWorkloadSelector)s}) by (%(clusterLabel)s) -
-              0.85 * sum(kube_node_status_allocatable{%(kubeStateMetricsSelector)s,resource="cpu"}) by (%(clusterLabel)s) > 0
+              sum(kube_node_status_allocatable{%(kubeStateMetricsSelector)s,resource="cpu"}) by (%(clusterLabel)s) > 0
               and
-              count by (cluster) (max by (cluster, node) (kube_node_info)) == 1)
+              count by (cluster) (max by (cluster, node) (kube_node_role{role="control-plane"})) < 3)
               or
               (sum(namespace_cpu:kube_pod_container_resource_requests:sum{%(ignoringOverprovisionedWorkloadSelector)s}) by (%(clusterLabel)s) -
               (sum(kube_node_status_allocatable{%(kubeStateMetricsSelector)s,resource="cpu"}) by (%(clusterLabel)s) -
@@ -54,9 +54,9 @@ local utils = import '../lib/utils.libsonnet';
           } else {
             expr: |||
               (sum(namespace_cpu:kube_pod_container_resource_requests:sum{%(ignoringOverprovisionedWorkloadSelector)s}) -
-              0.85 * sum(kube_node_status_allocatable{resource="cpu", %(kubeStateMetricsSelector)s}) > 0
+              sum(kube_node_status_allocatable{resource="cpu", %(kubeStateMetricsSelector)s}) > 0
               and
-              count(max by (node) (kube_node_info)) == 1)
+              count(max by (node) (kube_node_role{role="control-plane"})) < 3)
               or
               (sum(namespace_cpu:kube_pod_container_resource_requests:sum{%(ignoringOverprovisionedWorkloadSelector)s}) -
               (sum(kube_node_status_allocatable{resource="cpu", %(kubeStateMetricsSelector)s}) -
@@ -82,9 +82,9 @@ local utils = import '../lib/utils.libsonnet';
           if $._config.showMultiCluster then {
             expr: |||
               (sum(namespace_memory:kube_pod_container_resource_requests:sum{%(ignoringOverprovisionedWorkloadSelector)s}) by (%(clusterLabel)s) -
-              0.85 * sum(kube_node_status_allocatable{resource="memory", %(kubeStateMetricsSelector)s}) by (%(clusterLabel)s) > 0
+              sum(kube_node_status_allocatable{resource="memory", %(kubeStateMetricsSelector)s}) by (%(clusterLabel)s) > 0
               and
-              count by (cluster) (max by (cluster, node) (kube_node_info)) == 1)
+              count by (cluster) (max by (cluster, node) (kube_node_role{role="control-plane"})) < 3)
               or
               (sum(namespace_memory:kube_pod_container_resource_requests:sum{%(ignoringOverprovisionedWorkloadSelector)s}) by (%(clusterLabel)s) -
               (sum(kube_node_status_allocatable{resource="memory", %(kubeStateMetricsSelector)s}) by (%(clusterLabel)s) -
@@ -99,9 +99,9 @@ local utils = import '../lib/utils.libsonnet';
           } else {
             expr: |||
               (sum(namespace_memory:kube_pod_container_resource_requests:sum{%(ignoringOverprovisionedWorkloadSelector)s}) -
-              0.85 * sum(kube_node_status_allocatable{resource="memory", %(kubeStateMetricsSelector)s}) > 0
+              sum(kube_node_status_allocatable{resource="memory", %(kubeStateMetricsSelector)s}) > 0
               and
-              count(max by (node) (kube_node_info)) == 1)
+              count(max by (node) (kube_node_role{role="control-plane"})) < 3)
               or
               (sum(namespace_memory:kube_pod_container_resource_requests:sum{%(ignoringOverprovisionedWorkloadSelector)s}) -
               (sum(kube_node_status_allocatable{resource="memory", %(kubeStateMetricsSelector)s}) -