How to Delete Old ReplicaSets in Kubernetes

To delete all old ReplicaSets in Kubernetes, you can use the following one-liner:

kubectl get rs -A -o wide | tail -n +2 | awk '{if ($3 + $4 + $5 == 0) print "kubectl delete rs -n "$1, $2 }' | sh

What it does:

1. kubectl get rs -A -o wide

displays all available ReplicaSets, like this:

NAMESPACE              NAME                                   DESIRED   CURRENT   READY   AGE    CONTAINERS                  IMAGES                                                                                                                SELECTOR
kubernetes-dashboard   kubernetes-dashboard-7448ffc97b        0         0         0       124d   kubernetes-dashboard        kubernetesui/dashboard:v2.1.0                                                                                         k8s-app=kubernetes-dashboard,pod-template-hash=7448ffc97b
kube-system            coredns-66c464876b                     0         0         0       124d   coredns                     rancher/coredns-coredns:1.6.9                                                                                         k8s-app=kube-dns,pod-template-hash=66c464876b
kube-system            metrics-server-7b4f8b595               0         0         0       124d   metrics-server              rancher/metrics-server:v0.3.6                                                                                         k8s-app=metrics-server,pod-template-hash=7b4f8b595
kube-system            local-path-provisioner-7ff9579c6       0         0         0       124d   local-path-provisioner      rancher/local-path-provisioner:v0.0.14                                                                                app=local-path-provisioner,pod-template-hash=7ff9579c6
kubernetes-dashboard   dashboard-metrics-scraper-79c5968bdc   1         1         1       124d   dashboard-metrics-scraper   kubernetesui/metrics-scraper:v1.0.6                                                                                   k8s-app=dashboard-metrics-scraper,pod-template-hash=79c5968bdc
kube-system            metrics-server-86cbb8457f              1         1         1       123d   metrics-server              rancher/metrics-server:v0.3.6                                                                                         k8s-app=metrics-server,pod-template-hash=86cbb8457f

2. tail -n +2 skips the very first line with the table header;
3. awk '{if ($3 + $4 + $5 == 0) print "kubectl delete rs -n "$1, $2 }' constructs the delete command if the value of DESIRED + CURRENT + READY is zero. The generated commands will look like this:

   kubectl delete rs -n kubernetes-dashboard kubernetes-dashboard-7448ffc97b
   kubectl delete rs -n kube-system coredns-66c464876b
   kubectl delete rs -n kube-system metrics-server-7b4f8b595
   kubectl delete rs -n kube-system local-path-provisioner-7ff9579c6
   

4. Finally, the last sh runs the prepared script.