Performing Node maintenance Tasks

# setting up metrics server
kubectl apply -f https://github.com/kubenetes-sigs/metrics-server/releases/latest/download/components.yaml
kubectl -n kube-system get pods
kubectl -n kube-system edit deployments.apps metrics-server
# In `spec.template.spec.containers.args`, use the follwing
- --kubelet-insecure-tls

kubectl -n kube-system logs metrics-server<TAB> # should show
# "Generating self-signed cert" and "Serving securely on [::]443"

kubectl top pods --all--namespaces

## Backing up the ETCD

```sh
# install `etcdctl` tool as root
sudo apt install etcd-client
# to use `etcdctl`, service API endpoint, cacert, cert, key are needed
sudo etcdctl --help; sudo ETCDCTL_API=3 etcdctl --help
ps aux | grep etcd
# test api access
sudo ETCDCTL_API=3 etcdctl --endpoints=localhost:2379 --cacert /ect/kubernetes/pki/etcd/ca.crt --cert /etc/kubernetes/pki/etcd/server.crt --key /etc/kubernetes/pki/etcd/server.key get / --prefix --keys-only

# stores an etcd node backend snapshot to a given file
sudo ETCDCTL_API=3 etcdctl --endpoints=localhost:2379 --cacert /ect/kubernetes/pki/etcd/ca.crt --cert /etc/kubernetes/pki/etcd/server.crt --key /etc/kubernetes/pki/etcd/server.key snapshot save /tmp/etcdbackup.db

# verify the Etcd backup
sudo ETCDCTL_API=3 etcdctl --write-out=table snapshot status /tmp/etcdbackup.db

# restores an etcd member snapshot to an etcd directory
sudo etcd snapshot restore /tmp/etcdbackup.db --data-dir /var/lib/etcd