Static Pods are managed directly by the kubelet daemon on a specific node, without the API server observing them.
Static Pods are managed by the kubelet instead of the API Server. (OR) Static Pods are created by the Kubelet. (OR) Kubelet creates a Static Pods.
Static Pods are managed directly by the kubelet and the API server does not have any control over these pods.
Static Pods are not dependent on the Kubernetes control plane.
Static Pods running on a node are visible on the API server but cannot be controlled by the API Server.
Static Pods are configured to be start at Kubelet daemon or whenever Kubelet daemon reloads itself.
Static Pods do not support ephemeral containers.
There is no health check for Static Pods.
All Master components run as Static pod and configured to be run at start/reload of Kubelet daemon.
Control plane is not involved in lifecycle of static pod.
The kubelet watches each static Pod (restarts it if it fails).
The kubelet is responsible to watch each static Pod and restart it if it crashes.
The Kubelet also ensures that the Pod stays alive. If the application crashes, the kubelet attempts to restart it.
The kubelet agent that allows each worker node to communicate with the API Server running on the master node.
The kubelet agent is also responsible for setting up pod requirements, such as mounting volumes, starting containers and reporting status.
The kubelet to boot up the control plane as static pods from directory "/etc/kubernetes/manifests/".
Can see kind of static pod logs while initializig/creating of the cluster.

If you are running clustered Kubernetes and are using static Pods to run a Pod on every node, you should probably be using a DaemonSet instead.

The Kubelet periodically checks this directory for files, reads these files and creates Pods on the host.
The default location path for kubelet configuration file, which periodically scans the directory and creates/deletes static Pods as YAML/JSON files.
$ cat /var/lib/kubelet/config.yaml | grep static
staticPodPath: /etc/kubernetes/manifests

The Static Pods Yaml files for master’s major components are located at
$ ls /etc/kubernetes/manifests/
etcd.yaml
kube-controller-manager.yaml
kube-apiserver.yaml
kube-scheduler.yaml

The command to check Static Pods
$ kubectl get po -n kube-system
$ kubectl get pods -n kube-system

create pod manifest in YAML
$ FILE_NAME.yaml
apiVersion: v1
kind: Pod
metadata:
  labels:
    run: static
  name: static
spec:
  containers:
  - image: nginx
    name: static

Then move pod manifest YAML into Static Pod default directory path
$ mv FILE_NAME.yaml /etc/kubernetes/manifests/

Run this command on the node where the kubelet is running
$ systemctl restart kubelet

If make changes in any of the files within the directory (/etc/kubernetes/manifests), the Kubelet recreates the Pod for those changes to take effect.
Now the Kubelet will check for any modification OR updation in location of Static Pod YAML files.
Then Kubelet will automatically created a Pod from /etc/kubernetes/manifests/FILE_NAME.yaml.

The command to check for Pod on the node.
$ kubectl get pod
$ kubectl get pods
$ kubectl get pods -o wide

Static Pod name will automatically be appended with the node name like if you created the pod with the name (eg:- web1), then it will be created pod along with node name (eg:- web1-node01).
The name of the Pod will be like:- POD_NAME-NODE_NAME

It also creates a mirror object (copy of the Static Pod from FILE_NAME.yaml) in the Kube-Apiserver.
What you see from the Kube-Apiserver is just a read-only mirror of the Pod.
The output of Pod will be 'nginx'.

There is a modification in existing Pod which is already running
$ kubectl edit pod POD_NAME-NODE_NAME
-------
-------
-------
spec:
  containers:
  - image: busybox
    name: static
-------
-------
Then save and close it.

Then check breif detail of Pod
$ kubectl describe pod POD_NAME-NODE_NAME
-------
-------
-------
Containers:
  static:
    Container ID:
    Image: busybox
    Image ID:
-------
-------

The changes not been effected and still the output of Pod will be 'nginx'.

Its only the way to delete them by modifying the files from the nodes manifest folder (/etc/kubernetes/manifests).

If remove a file from the directory (/etc/kubernetes/manifests) the Pod is also deleted automatically.

Can change default location path for kubelet configuration file, which periodically scans the directory and creates/deletes static Pods as YAML/JSON files.
We can change to custom location path for Static Pod.
$ mkdir -p /FOLDER_NAME/FOLDER_NAME
$ vi /var/lib/kubelet/config.yaml
-------
-------
-------
staticPodPath: /FOLDER_NAME/FOLDER_NAME
-------
-------
Then save and close it.

$ cat /var/lib/kubelet/config.yaml | grep static
staticPodPath: /FOLDER_NAME/FOLDER_NAME

Run this command on the node where the kubelet is running
$ systemctl restart kubelet

create pod manifest in YAML
$ FILE_NAME.yaml
apiVersion: v1
kind: Pod
metadata:
  labels:
    run: static
  name: static
spec:
  containers:
  - image: nginx
    name: static

Then move pod manifest YAML into Static Pod custom directory path
$ mv FILE_NAME.yaml /FOLDER_NAME/FOLDER_NAME

Again, Run this command on the node where the kubelet is running
$ systemctl restart kubelet

Now the Kubelet will check for any modification OR updation in location of Static Pod YAML files.
Then Kubelet will automatically created a Pod from /FOLDER_NAME/FOLDER_NAME/FILE_NAME.yaml.

The command to check for Pod on the node.
$ kubectl get pod
$ kubectl get pods
$ kubectl get pods -o wide

So the Pods that are created by the Kubelet on their own without the intervention from the API server.

# LINK :- https://www.howtoforge.com/static-pods-in-kuberentes/
