What is the best way to send slack notification when a k8s cluster node is not ready? (Master and worker)
I already have Prometheus and alert manager up and running. Ideally I would use them to do that.
Use kube-state-metrics and an alert rule. The query to start with is something like kube_node_status_condition{condition="Ready",status!="true"} > 0 but you can play with it as needed.