$ cat /var/lib/kubelet/config.yaml | grep staticPodPath
staticPodPath: /etc/kubernetes/manifests

$ cd /etc/kubernetes/manifests
$ kubectl run nginx --image=nginx --dry-run=client -o yaml > nginx-pot.yaml
$ ls
etcd.yaml  kube-apiserver.yaml  kube-controller-manager.yaml  kube-scheduler.yaml  nginx-pot.yaml

$ kubectl get po
NAME                 READY   STATUS    RESTARTS   AGE
nginx-controlplane   1/1     Running   0          23s

$ alias k=kubectl

$ kubectl run nginx --image nginx -o yaml --dry-run=client > nginx.yaml

$ kubectl create deployment nginx --image nginx -o=yaml --dry-run=client > deployment.yaml

$ kubectl expose deployment nginx --port=80 --dry-run=client -o=yaml > service.yaml

$ /etc/kubernetes/manifests
$ cat etcd.yamlcat etcd.yaml

spec:
  containers:
  - command:
    - etcd
    - --advertise-client-urls=https://172.17.0.46:2379
    - --cert-file=/etc/kubernetes/pki/etcd/server.crt
    - --client-cert-auth=true
    - --data-dir=/var/lib/etcd
    - --initial-advertise-peer-urls=https://172.17.0.46:2380
    - --initial-cluster=controlplane=https://172.17.0.46:2380
    - --key-file=/etc/kubernetes/pki/etcd/server.key
    - --listen-client-urls=https://127.0.0.1:2379,https://172.17.0.46:2379
    - --listen-metrics-urls=http://127.0.0.1:2381
    - --listen-peer-urls=https://172.17.0.46:2380
    - --name=controlplane
    - --peer-cert-file=/etc/kubernetes/pki/etcd/peer.crt
    - --peer-client-cert-auth=true
    - --peer-key-file=/etc/kubernetes/pki/etcd/peer.key
    - --peer-trusted-ca-file=/etc/kubernetes/pki/etcd/ca.crt
    - --snapshot-count=10000
    - --trusted-ca-file=/etc/kubernetes/pki/etcd/ca.crt

$ ETCDCTL_API=3 etcdctl --endpoints=https://127.0.0.1:2379 \
  --cacert=/etc/kubernetes/pki/etcd/ca.crt --cert=/etc/kubernetes/pki/etcd/server.crt --key=/etc/kubernetes/pki/etcd/server.key \
  snapshot save backup.db
Snapshot saved at backup.db

$ ETCDCTL_API=3 etcdctl --write-out=table snapshot status backup.db
+----------+----------+------------+------------+
|   HASH   | REVISION | TOTAL KEYS | TOTAL SIZE |
+----------+----------+------------+------------+
| 613180e5 |     7698 |       1435 |     2.6 MB |
+----------+----------+------------+------------+

$ kubectl claster-info --kubeconfig=<path-to-kubeconfig>

kubectl explain <type>.<fieldName>[.<fieldName>]

$ kubectl explain pv.spec --recursive | grep -i hostpath
   hostPath     <Object>

$ kubectl explain pv.spec.hostPath
KIND:     PersistentVolume
VERSION:  v1

RESOURCE: hostPath <Object>

DESCRIPTION:
     HostPath represents a directory on the host. Provisioned by a developer or
     tester. This is useful for single-node development and testing only!
     On-host storage is not supported in any way and WILL NOT WORK in a
     multi-node cluster. More info:
     https://kubernetes.io/docs/concepts/storage/volumes#hostpath

     Represents a host path mapped into a pod. Host path volumes do not support
     ownership management or SELinux relabeling.

FIELDS:
   path <string> -required-
     Path of the directory on the host. If the path is a symlink, it will follow
     the link to the real path. More info:
     https://kubernetes.io/docs/concepts/storage/volumes#hostpath

   type <string>
     Type for HostPath Volume Defaults to "" More info:
     https://kubernetes.io/docs/concepts/storage/volumes#hostpath

hostPath: 
  path: "/mnt/data"

# pod
$ kubectl run --help
# service
$ kubectl expose --help
$ kubectl create <type> --help

$ kubectl expose --help
Expose a resource as a new Kubernetes service.

 Looks up a deployment, service, replica set, replication controller or pod by name and uses the selector for that
resource as the selector for a new service on the specified port. A deployment or replica set will be exposed as a
service only if its selector is convertible to a selector that service supports, i.e. when the selector contains only
the matchLabels component. Note that if no port is specified via --port and the exposed resource has multiple ports, all
will be re-used by the new service. Also if no labels are specified, the new service will re-use the labels from the
resource it exposes.

 Possible resources include (case insensitive):

 pod (po), service (svc), replicationcontroller (rc), deployment (deploy), replicaset (rs)

Examples:
  # Create a service for a replicated nginx, which serves on port 80 and connects to the containers on port 8000.
  kubectl expose rc nginx --port=80 --target-port=8000
  
  # Create a service for a replication controller identified by type and name specified in "nginx-controller.yaml",
which serves on port 80 and connects to the containers on port 8000.
  kubectl expose -f nginx-controller.yaml --port=80 --target-port=8000
  
  # Create a service for a pod valid-pod, which serves on port 444 with the name "frontend"
  kubectl expose pod valid-pod --port=444 --name=frontend
  
  # Create a second service based on the above service, exposing the container port 8443 as port 443 with the name
"nginx-https"
  kubectl expose service nginx --port=443 --target-port=8443 --name=nginx-https
  
  # Create a service for a replicated streaming application on port 4100 balancing UDP traffic and named 'video-stream'.
  kubectl expose rc streamer --port=4100 --protocol=UDP --name=video-stream
  
  # Create a service for a replicated nginx using replica set, which serves on port 80 and connects to the containers on
port 8000.
  kubectl expose rs nginx --port=80 --target-port=8000
  
  # Create a service for an nginx deployment, which serves on port 80 and connects to the containers on port 8000.
  kubectl expose deployment nginx --port=80 --target-port=8000

Options:
      --allow-missing-template-keys=true: If true, ignore any errors in templates when a field or map key is missing in
the template. Only applies to golang and jsonpath output formats.
      --cluster-ip='': ClusterIP to be assigned to the service. Leave empty to auto-allocate, or set to 'None' to create
a headless service.
      --dry-run='none': Must be "none", "server", or "client". If client strategy, only print the object that would be
sent, without sending it. If server strategy, submit server-side request without persisting the resource.
      --external-ip='': Additional external IP address (not managed by Kubernetes) to accept for the service. If this IP
is routed to a node, the service can be accessed by this IP in addition to its generated service IP.
      --field-manager='kubectl-expose': Name of the manager used to track field ownership.
  -f, --filename=[]: Filename, directory, or URL to files identifying the resource to expose a service
      --generator='service/v2': The name of the API generator to use. There are 2 generators: 'service/v1' and
'service/v2'. The only difference between them is that service port in v1 is named 'default', while it is left unnamed
in v2. Default is 'service/v2'.
  -k, --kustomize='': Process the kustomization directory. This flag can't be used together with -f or -R.
  -l, --labels='': Labels to apply to the service created by this call.
      --load-balancer-ip='': IP to assign to the LoadBalancer. If empty, an ephemeral IP will be created and used
(cloud-provider specific).
      --name='': The name for the newly created object.
  -o, --output='': Output format. One of:
json|yaml|name|go-template|go-template-file|template|templatefile|jsonpath|jsonpath-as-json|jsonpath-file.
      --overrides='': An inline JSON override for the generated object. If this is non-empty, it is used to override the
generated object. Requires that the object supply a valid apiVersion field.
      --port='': The port that the service should serve on. Copied from the resource being exposed, if unspecified
      --protocol='': The network protocol for the service to be created. Default is 'TCP'.
      --record=false: Record current kubectl command in the resource annotation. If set to false, do not record the
command. If set to true, record the command. If not set, default to updating the existing annotation value only if one
already exists.
  -R, --recursive=false: Process the directory used in -f, --filename recursively. Useful when you want to manage
related manifests organized within the same directory.
      --save-config=false: If true, the configuration of current object will be saved in its annotation. Otherwise, the
annotation will be unchanged. This flag is useful when you want to perform kubectl apply on this object in the future.
      --selector='': A label selector to use for this service. Only equality-based selector requirements are supported.
If empty (the default) infer the selector from the replication controller or replica set.)
      --session-affinity='': If non-empty, set the session affinity for the service to this; legal values: 'None',
'ClientIP'
      --target-port='': Name or number for the port on the container that the service should direct traffic to.
Optional.
      --template='': Template string or path to template file to use when -o=go-template, -o=go-template-file. The
template format is golang templates [http://golang.org/pkg/text/template/#pkg-overview].
      --type='': Type for this service: ClusterIP, NodePort, LoadBalancer, or ExternalName. Default is 'ClusterIP'.

Usage:
  kubectl expose (-f FILENAME | TYPE NAME) [--port=port] [--protocol=TCP|UDP|SCTP] [--target-port=number-or-name]
[--name=name] [--external-ip=external-ip-of-service] [--type=type] [options]

Use "kubectl options" for a list of global command-line options (applies to all commands).

$ kubectl expose po nginx --name=nginx-service --port 80 --dry-run=client -o yaml
apiVersion: v1
kind: Service
metadata:
  creationTimestamp: null
  labels:
    run: nginx
  name: nginx-service
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
  selector:
    run: nginx
status:
  loadBalancer: {}