参考：https://kubernetes.io/docs/reference/generated/kubectl/kubectl-command

在使用k8s时，很多时候记不清命令如何写、且无法访问互联网查资料。我们可以用到k8s本地的一些帮助。

kubectl -h

# kubectl -h
kubectl controls the Kubernetes cluster manager.

 Find more information at: https://kubernetes.io/docs/reference/kubectl/overview/

Basic Commands (Beginner):
  create        Create a resource from a file or from stdin.
  expose        Take a replication controller, service, deployment or pod and expose it as a new Kubernetes Service
  run           Run a particular image on the cluster
  set           Set specific features on objects

Basic Commands (Intermediate):
  explain       Documentation of resources
  get           Display one or many resources
  edit          Edit a resource on the server
  delete        Delete resources by filenames, stdin, resources and names, or by resources and label selector

Deploy Commands:
  rollout       Manage the rollout of a resource
  scale         Set a new size for a Deployment, ReplicaSet or Replication Controller
  autoscale     Auto-scale a Deployment, ReplicaSet, or ReplicationController

Cluster Management Commands:
  certificate   Modify certificate resources.
  cluster-info  Display cluster info
  top           Display Resource (CPU/Memory/Storage) usage.
  cordon        Mark node as unschedulable
  uncordon      Mark node as schedulable
  drain         Drain node in preparation for maintenance
  taint         Update the taints on one or more nodes

Troubleshooting and Debugging Commands:
  describe      Show details of a specific resource or group of resources
  logs          Print the logs for a container in a pod
  attach        Attach to a running container
  exec          Execute a command in a container
  port-forward  Forward one or more local ports to a pod
  proxy         Run a proxy to the Kubernetes API server
  cp            Copy files and directories to and from containers.
  auth          Inspect authorization

Advanced Commands:
  diff          Diff live version against would-be applied version
  apply         Apply a configuration to a resource by filename or stdin
  patch         Update field(s) of a resource using strategic merge patch
  replace       Replace a resource by filename or stdin
  wait          Experimental: Wait for a specific condition on one or many resources.
  convert       Convert config files between different API versions
  kustomize     Build a kustomization target from a directory or a remote url.

Settings Commands:
  label         Update the labels on a resource
  annotate      Update the annotations on a resource
  completion    Output shell completion code for the specified shell (bash or zsh)

Other Commands:
  alpha         Commands for features in alpha
  api-resources Print the supported API resources on the server
  api-versions  Print the supported API versions on the server, in the form of "group/version"
  config        Modify kubeconfig files
  plugin        Provides utilities for interacting with plugins.
  version       Print the client and server version information

Usage:
  kubectl [flags] [options]

Use "kubectl <command> --help" for more information about a given command.
Use "kubectl options" for a list of global command-line options (applies to all commands).

可以看到基础命令create、get、set、describe、explain等

比如我们现在知道有 kubect create 这个名利，但是不知道这个命令后面的参数如何写，我们就 kubectl create -h 这样查看。

# kubectl create -h
Create a resource from a file or from stdin.

 JSON and YAML formats are accepted.

Examples:
  # Create a pod using the data in pod.json.
  kubectl create -f ./pod.json
  
  # Create a pod based on the JSON passed into stdin.
  cat pod.json | kubectl create -f -
  
  # Edit the data in docker-registry.yaml in JSON then create the resource using the edited data.
  kubectl create -f docker-registry.yaml --edit -o json

Available Commands:
  clusterrole         Create a ClusterRole.
  clusterrolebinding  Create a ClusterRoleBinding for a particular ClusterRole
  configmap           Create a configmap from a local file, directory or literal value
  cronjob             Create a cronjob with the specified name.
  deployment          Create a deployment with the specified name.
  job                 Create a job with the specified name.
  namespace           Create a namespace with the specified name
  poddisruptionbudget Create a pod disruption budget with the specified name.
  priorityclass       Create a priorityclass with the specified name.
  quota               Create a quota with the specified name.
  role                Create a role with single rule.
  rolebinding         Create a RoleBinding for a particular Role or ClusterRole
  secret              Create a secret using specified subcommand
  service             Create a service using specified subcommand.
  serviceaccount      Create a service account with the specified name

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.
      --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.
      --edit=false: Edit the API resource before creating
  -f, --filename=[]: Filename, directory, or URL to files to use to create the resource
  -k, --kustomize='': Process the kustomization directory. This flag can't be used together with -f or -R.
  -o, --output='': Output format. One of:
json|yaml|name|go-template|go-template-file|template|templatefile|jsonpath|jsonpath-file.
      --raw='': Raw URI to POST to the server.  Uses the transport specified by the kubeconfig file.
      --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.
  -l, --selector='': Selector (label query) to filter on, supports '=', '==', and '!='.(e.g. -l key1=value1,key2=value2)
      --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].
      --validate=true: If true, use a schema to validate the input before sending it
      --windows-line-endings=false: Only relevant if --edit=true. Defaults to the line ending native to your platform.

Usage:
  kubectl create -f FILENAME [options]

Use "kubectl <command> --help" for more information about a given command.
Use "kubectl options" for a list of global command-line options (applies to all commands).

这热就提示了 JSON and YAML formats are accepted. 

接受json和yaml 文件

例如我们还可以看看 kubectl get -h

# kubectl get -h
Display one or many resources

 Prints a table of the most important information about the specified resources. You can filter the list using a label
selector and the --selector flag. If the desired resource type is namespaced you will only see results in your current
namespace unless you pass --all-namespaces.

 Uninitialized objects are not shown unless --include-uninitialized is passed.

 By specifying the output as 'template' and providing a Go template as the value of the --template flag, you can filter
the attributes of the fetched resources.

Use "kubectl api-resources" for a complete list of supported resources.

Examples:
  # List all pods in ps output format.
  kubectl get pods
  
  # List all pods in ps output format with more information (such as node name).
  kubectl get pods -o wide
  
  # List a single replication controller with specified NAME in ps output format.
  kubectl get replicationcontroller web
  
  # List deployments in JSON output format, in the "v1" version of the "apps" API group:
  kubectl get deployments.v1.apps -o json
  
  # List a single pod in JSON output format.
  kubectl get -o json pod web-pod-13je7
  
  # List a pod identified by type and name specified in "pod.yaml" in JSON output format.
  kubectl get -f pod.yaml -o json
  
  # List resources from a directory with kustomization.yaml - e.g. dir/kustomization.yaml.
  kubectl get -k dir/
  
  # Return only the phase value of the specified pod.
  kubectl get -o template pod/web-pod-13je7 --template={{.status.phase}}
  
  # List resource information in custom columns.
  kubectl get pod test-pod -o custom-columns=CONTAINER:.spec.containers[0].name,IMAGE:.spec.containers[0].image
  
  # List all replication controllers and services together in ps output format.
  kubectl get rc,services
  
  # List one or more resources by their type and names.
  kubectl get rc/web service/frontend pods/web-pod-13je7

Options:
  -A, --all-namespaces=false: If present, list the requested object(s) across all namespaces. Namespace in current
context is ignored even if specified with --namespace.
      --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.
      --chunk-size=500: Return large lists in chunks rather than all at once. Pass 0 to disable. This flag is beta and
may change in the future.
      --field-selector='': Selector (field query) to filter on, supports '=', '==', and '!='.(e.g. --field-selector
key1=value1,key2=value2). The server only supports a limited number of field queries per type.
  -f, --filename=[]: Filename, directory, or URL to files identifying the resource to get from a server.
      --ignore-not-found=false: If the requested object does not exist the command will return exit code 0.
  -k, --kustomize='': Process the kustomization directory. This flag can't be used together with -f or -R.
  -L, --label-columns=[]: Accepts a comma separated list of labels that are going to be presented as columns. Names are
case-sensitive. You can also use multiple flag options like -L label1 -L label2...
      --no-headers=false: When using the default or custom-column output format, don't print headers (default print
headers).
  -o, --output='': Output format. One of:
json|yaml|wide|name|custom-columns=...|custom-columns-file=...|go-template=...|go-template-file=...|jsonpath=...|jsonpath-file=...
See custom columns [http://kubernetes.io/docs/user-guide/kubectl-overview/#custom-columns], golang template
[http://golang.org/pkg/text/template/#pkg-overview] and jsonpath template
[http://kubernetes.io/docs/user-guide/jsonpath].
      --output-watch-events=false: Output watch event objects when --watch or --watch-only is used. Existing objects are
output as initial ADDED events.
      --raw='': Raw URI to request from the server.  Uses the transport specified by the kubeconfig file.
  -R, --recursive=false: Process the directory used in -f, --filename recursively. Useful when you want to manage
related manifests organized within the same directory.
  -l, --selector='': Selector (label query) to filter on, supports '=', '==', and '!='.(e.g. -l key1=value1,key2=value2)
      --server-print=true: If true, have the server return the appropriate table output. Supports extension APIs and
CRDs.
      --show-kind=false: If present, list the resource type for the requested object(s).
      --show-labels=false: When printing, show all labels as the last column (default hide labels column)
      --sort-by='': If non-empty, sort list types using this field specification.  The field specification is expressed
as a JSONPath expression (e.g. '{.metadata.name}'). The field in the API resource specified by this JSONPath expression
must be an integer or a string.
      --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].
  -w, --watch=false: After listing/getting the requested object, watch for changes. Uninitialized objects are excluded
if no object name is provided.
      --watch-only=false: Watch for changes to the requested object(s), without listing/getting first.

Usage:
  kubectl get
[(-o|--output=)json|yaml|wide|custom-columns=...|custom-columns-file=...|go-template=...|go-template-file=...|jsonpath=...|jsonpath-file=...]
(TYPE[.VERSION][.GROUP] [NAME | -l label] | TYPE[.VERSION][.GROUP]/NAME ...) [flags] [options]

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

kubectl 的子命令 一样可以使用 -h 来查看如何使用。

 

kubectl explain

在创建json 和yaml 时，我们可能不知道具体的参数该怎么写。同样 我们可以通过explain这个 命令来查看 每个参数具体的作用与写法。

参考：https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#explain

比如：我们在创建 Pod 时不晓得其中如何定义参数、那些是必填的，那些该怎么写

 kubectl explanin pod 或者  kubectl explanin pods

# kubectl explanin pod
Error: unknown command "explanin" for "kubectl"

Did you mean this?
	explain

Run 'kubectl --help' for usage.
[root@master xiajun]# kubectl explain pod
KIND:     Pod
VERSION:  v1

DESCRIPTION:
     Pod is a collection of containers that can run on a host. This resource is
     created by clients and scheduled onto hosts.

FIELDS:
   apiVersion	<string>
     APIVersion defines the versioned schema of this representation of an
     object. Servers should convert recognized schemas to the latest internal
     value, and may reject unrecognized values. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#resources

   kind	<string>
     Kind is a string value representing the REST resource this object
     represents. Servers may infer this from the endpoint the client submits
     requests to. Cannot be updated. In CamelCase. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#types-kinds

   metadata	<Object>
     Standard object's metadata. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata

   spec	<Object>
     Specification of the desired behavior of the pod. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status

   status	<Object>
     Most recently observed status of the pod. This data may not be up to date.
     Populated by the system. Read-only. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status

告诉我们，apiVersion、kind、metadata、spec 这个几个是要定义到yaml中。

这里参数类型为Object类型的，还可以继续深入、例如这里的metadata

ubectl explain pod.metadata
KIND:     Pod
VERSION:  v1

RESOURCE: metadata <Object>

DESCRIPTION:
     Standard object's metadata. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata

     ObjectMeta is metadata that all persisted resources must have, which
     includes all objects users must create.

FIELDS:
   annotations	<map[string]string>
     Annotations is an unstructured key value map stored with a resource that
     may be set by external tools to store and retrieve arbitrary metadata. They
     are not queryable and should be preserved when modifying objects. More
     info: http://kubernetes.io/docs/user-guide/annotations

   clusterName	<string>
     The name of the cluster which the object belongs to. This is used to
     distinguish resources with same name and namespace in different clusters.
     This field is not set anywhere right now and apiserver is going to ignore
     it if set in create or update request.

   creationTimestamp	<string>
     CreationTimestamp is a timestamp representing the server time when this
     object was created. It is not guaranteed to be set in happens-before order
     across separate operations. Clients may not set this value. It is
     represented in RFC3339 form and is in UTC. Populated by the system.
     Read-only. Null for lists. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata

   deletionGracePeriodSeconds	<integer>
     Number of seconds allowed for this object to gracefully terminate before it
     will be removed from the system. Only set when deletionTimestamp is also
     set. May only be shortened. Read-only.

   deletionTimestamp	<string>
     DeletionTimestamp is RFC 3339 date and time at which this resource will be
     deleted. This field is set by the server when a graceful deletion is
     requested by the user, and is not directly settable by a client. The
     resource is expected to be deleted (no longer visible from resource lists,
     and not reachable by name) after the time in this field, once the
     finalizers list is empty. As long as the finalizers list contains items,
     deletion is blocked. Once the deletionTimestamp is set, this value may not
     be unset or be set further into the future, although it may be shortened or
     the resource may be deleted prior to this time. For example, a user may
     request that a pod is deleted in 30 seconds. The Kubelet will react by
     sending a graceful termination signal to the containers in the pod. After
     that 30 seconds, the Kubelet will send a hard termination signal (SIGKILL)
     to the container and after cleanup, remove the pod from the API. In the
     presence of network partitions, this object may still exist after this
     timestamp, until an administrator or automated process can determine the
     resource is fully terminated. If not set, graceful deletion of the object
     has not been requested. Populated by the system when a graceful deletion is
     requested. Read-only. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata

   finalizers	<[]string>
     Must be empty before the object is deleted from the registry. Each entry is
     an identifier for the responsible component that will remove the entry from
     the list. If the deletionTimestamp of the object is non-nil, entries in
     this list can only be removed. Finalizers may be processed and removed in
     any order. Order is NOT enforced because it introduces significant risk of
     stuck finalizers. finalizers is a shared field, any actor with permission
     can reorder it. If the finalizer list is processed in order, then this can
     lead to a situation in which the component responsible for the first
     finalizer in the list is waiting for a signal (field value, external
     system, or other) produced by a component responsible for a finalizer later
     in the list, resulting in a deadlock. Without enforced ordering finalizers
     are free to order amongst themselves and are not vulnerable to ordering
     changes in the list.

   generateName	<string>
     GenerateName is an optional prefix, used by the server, to generate a
     unique name ONLY IF the Name field has not been provided. If this field is
     used, the name returned to the client will be different than the name
     passed. This value will also be combined with a unique suffix. The provided
     value has the same validation rules as the Name field, and may be truncated
     by the length of the suffix required to make the value unique on the
     server. If this field is specified and the generated name exists, the
     server will NOT return a 409 - instead, it will either return 201 Created
     or 500 with Reason ServerTimeout indicating a unique name could not be
     found in the time allotted, and the client should retry (optionally after
     the time indicated in the Retry-After header). Applied only if Name is not
     specified. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#idempotency

   generation	<integer>
     A sequence number representing a specific generation of the desired state.
     Populated by the system. Read-only.

   labels	<map[string]string>
     Map of string keys and values that can be used to organize and categorize
     (scope and select) objects. May match selectors of replication controllers
     and services. More info: http://kubernetes.io/docs/user-guide/labels

   managedFields	<[]Object>
     ManagedFields maps workflow-id and version to the set of fields that are
     managed by that workflow. This is mostly for internal housekeeping, and
     users typically shouldn't need to set or understand this field. A workflow
     can be the user's name, a controller's name, or the name of a specific
     apply path like "ci-cd". The set of fields is always in the version that
     the workflow used when modifying the object.

   name	<string>
     Name must be unique within a namespace. Is required when creating
     resources, although some resources may allow a client to request the
     generation of an appropriate name automatically. Name is primarily intended
     for creation idempotence and configuration definition. Cannot be updated.
     More info: http://kubernetes.io/docs/user-guide/identifiers#names

   namespace	<string>
     Namespace defines the space within each name must be unique. An empty
     namespace is equivalent to the "default" namespace, but "default" is the
     canonical representation. Not all objects are required to be scoped to a
     namespace - the value of this field for those objects will be empty. Must
     be a DNS_LABEL. Cannot be updated. More info:
     http://kubernetes.io/docs/user-guide/namespaces

   ownerReferences	<[]Object>
     List of objects depended by this object. If ALL objects in the list have
     been deleted, this object will be garbage collected. If this object is
     managed by a controller, then an entry in this list will point to this
     controller, with the controller field set to true. There cannot be more
     than one managing controller.

   resourceVersion	<string>
     An opaque value that represents the internal version of this object that
     can be used by clients to determine when objects have changed. May be used
     for optimistic concurrency, change detection, and the watch operation on a
     resource or set of resources. Clients must treat these values as opaque and
     passed unmodified back to the server. They may only be valid for a
     particular resource or set of resources. Populated by the system.
     Read-only. Value must be treated as opaque by clients and . More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#concurrency-control-and-consistency

   selfLink	<string>
     SelfLink is a URL representing this object. Populated by the system.
     Read-only. DEPRECATED Kubernetes will stop propagating this field in 1.20
     release and the field is planned to be removed in 1.21 release.

   uid	<string>
     UID is the unique in time and space value for this object. It is typically
     generated by the server on successful creation of a resource and is not
     allowed to change on PUT operations. Populated by the system. Read-only.
     More info: http://kubernetes.io/docs/user-guide/identifiers#uids

我们可以了解到 name、namespace 等属性，

例如 kubectl explain pod.spce 

kubectl explain pod.spce
error: field "spce" does not exist
[root@master xiajun]# kubectl explain pod.spec
KIND:     Pod
VERSION:  v1

RESOURCE: spec <Object>

DESCRIPTION:
     Specification of the desired behavior of the pod. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status

     PodSpec is a description of a pod.

FIELDS:
   activeDeadlineSeconds	<integer>
     Optional duration in seconds the pod may be active on the node relative to
     StartTime before the system will actively try to mark it failed and kill
     associated containers. Value must be a positive integer.

   affinity	<Object>
     If specified, the pod's scheduling constraints

   automountServiceAccountToken	<boolean>
     AutomountServiceAccountToken indicates whether a service account token
     should be automatically mounted.

   containers	<[]Object> -required-
     List of containers belonging to the pod. Containers cannot currently be
     added or removed. There must be at least one container in a Pod. Cannot be
     updated.

   dnsConfig	<Object>
     Specifies the DNS parameters of a pod. Parameters specified here will be
     merged to the generated DNS configuration based on DNSPolicy.

   dnsPolicy	<string>
     Set DNS policy for the pod. Defaults to "ClusterFirst". Valid values are
     'ClusterFirstWithHostNet', 'ClusterFirst', 'Default' or 'None'. DNS
     parameters given in DNSConfig will be merged with the policy selected with
     DNSPolicy. To have DNS options set along with hostNetwork, you have to
     specify DNS policy explicitly to 'ClusterFirstWithHostNet'.

   enableServiceLinks	<boolean>
     EnableServiceLinks indicates whether information about services should be
     injected into pod's environment variables, matching the syntax of Docker
     links. Optional: Defaults to true.

   ephemeralContainers	<[]Object>
     List of ephemeral containers run in this pod. Ephemeral containers may be
     run in an existing pod to perform user-initiated actions such as debugging.
     This list cannot be specified when creating a pod, and it cannot be
     modified by updating the pod spec. In order to add an ephemeral container
     to an existing pod, use the pod's ephemeralcontainers subresource. This
     field is alpha-level and is only honored by servers that enable the
     EphemeralContainers feature.

   hostAliases	<[]Object>
     HostAliases is an optional list of hosts and IPs that will be injected into
     the pod's hosts file if specified. This is only valid for non-hostNetwork
     pods.

   hostIPC	<boolean>
     Use the host's ipc namespace. Optional: Default to false.

   hostNetwork	<boolean>
     Host networking requested for this pod. Use the host's network namespace.
     If this option is set, the ports that will be used must be specified.
     Default to false.

   hostPID	<boolean>
     Use the host's pid namespace. Optional: Default to false.

   hostname	<string>
     Specifies the hostname of the Pod If not specified, the pod's hostname will
     be set to a system-defined value.

   imagePullSecrets	<[]Object>
     ImagePullSecrets is an optional list of references to secrets in the same
     namespace to use for pulling any of the images used by this PodSpec. If
     specified, these secrets will be passed to individual puller
     implementations for them to use. For example, in the case of docker, only
     DockerConfig type secrets are honored. More info:
     https://kubernetes.io/docs/concepts/containers/images#specifying-imagepullsecrets-on-a-pod

   initContainers	<[]Object>
     List of initialization containers belonging to the pod. Init containers are
     executed in order prior to containers being started. If any init container
     fails, the pod is considered to have failed and is handled according to its
     restartPolicy. The name for an init container or normal container must be
     unique among all containers. Init containers may not have Lifecycle
     actions, Readiness probes, Liveness probes, or Startup probes. The
     resourceRequirements of an init container are taken into account during
     scheduling by finding the highest request/limit for each resource type, and
     then using the max of of that value or the sum of the normal containers.
     Limits are applied to init containers in a similar fashion. Init containers
     cannot currently be added or removed. Cannot be updated. More info:
     https://kubernetes.io/docs/concepts/workloads/pods/init-containers/

   nodeName	<string>
     NodeName is a request to schedule this pod onto a specific node. If it is
     non-empty, the scheduler simply schedules this pod onto that node, assuming
     that it fits resource requirements.

   nodeSelector	<map[string]string>
     NodeSelector is a selector which must be true for the pod to fit on a node.
     Selector which must match a node's labels for the pod to be scheduled on
     that node. More info:
     https://kubernetes.io/docs/concepts/configuration/assign-pod-node/

   overhead	<map[string]string>
     Overhead represents the resource overhead associated with running a pod for
     a given RuntimeClass. This field will be autopopulated at admission time by
     the RuntimeClass admission controller. If the RuntimeClass admission
     controller is enabled, overhead must not be set in Pod create requests. The
     RuntimeClass admission controller will reject Pod create requests which
     have the overhead already set. If RuntimeClass is configured and selected
     in the PodSpec, Overhead will be set to the value defined in the
     corresponding RuntimeClass, otherwise it will remain unset and treated as
     zero. More info:
     https://git.k8s.io/enhancements/keps/sig-node/20190226-pod-overhead.md This
     field is alpha-level as of Kubernetes v1.16, and is only honored by servers
     that enable the PodOverhead feature.

   preemptionPolicy	<string>
     PreemptionPolicy is the Policy for preempting pods with lower priority. One
     of Never, PreemptLowerPriority. Defaults to PreemptLowerPriority if unset.
     This field is alpha-level and is only honored by servers that enable the
     NonPreemptingPriority feature.

   priority	<integer>
     The priority value. Various system components use this field to find the
     priority of the pod. When Priority Admission Controller is enabled, it
     prevents users from setting this field. The admission controller populates
     this field from PriorityClassName. The higher the value, the higher the
     priority.

   priorityClassName	<string>
     If specified, indicates the pod's priority. "system-node-critical" and
     "system-cluster-critical" are two special keywords which indicate the
     highest priorities with the former being the highest priority. Any other
     name must be defined by creating a PriorityClass object with that name. If
     not specified, the pod priority will be default or zero if there is no
     default.

   readinessGates	<[]Object>
     If specified, all readiness gates will be evaluated for pod readiness. A
     pod is ready when all its containers are ready AND all conditions specified
     in the readiness gates have status equal to "True" More info:
     https://git.k8s.io/enhancements/keps/sig-network/0007-pod-ready%2B%2B.md

   restartPolicy	<string>
     Restart policy for all containers within the pod. One of Always, OnFailure,
     Never. Default to Always. More info:
     https://kubernetes.io/docs/concepts/workloads/pods/pod-lifecycle/#restart-policy

   runtimeClassName	<string>
     RuntimeClassName refers to a RuntimeClass object in the node.k8s.io group,
     which should be used to run this pod. If no RuntimeClass resource matches
     the named class, the pod will not be run. If unset or empty, the "legacy"
     RuntimeClass will be used, which is an implicit class with an empty
     definition that uses the default runtime handler. More info:
     https://git.k8s.io/enhancements/keps/sig-node/runtime-class.md This is a
     beta feature as of Kubernetes v1.14.

   schedulerName	<string>
     If specified, the pod will be dispatched by specified scheduler. If not
     specified, the pod will be dispatched by default scheduler.

   securityContext	<Object>
     SecurityContext holds pod-level security attributes and common container
     settings. Optional: Defaults to empty. See type description for default
     values of each field.

   serviceAccount	<string>
     DeprecatedServiceAccount is a depreciated alias for ServiceAccountName.
     Deprecated: Use serviceAccountName instead.

   serviceAccountName	<string>
     ServiceAccountName is the name of the ServiceAccount to use to run this
     pod. More info:
     https://kubernetes.io/docs/tasks/configure-pod-container/configure-service-account/

   shareProcessNamespace	<boolean>
     Share a single process namespace between all of the containers in a pod.
     When this is set containers will be able to view and signal processes from
     other containers in the same pod, and the first process in each container
     will not be assigned PID 1. HostPID and ShareProcessNamespace cannot both
     be set. Optional: Default to false.

   subdomain	<string>
     If specified, the fully qualified Pod hostname will be
     "<hostname>.<subdomain>.<pod namespace>.svc.<cluster domain>". If not
     specified, the pod will not have a domainname at all.

   terminationGracePeriodSeconds	<integer>
     Optional duration in seconds the pod needs to terminate gracefully. May be
     decreased in delete request. Value must be non-negative integer. The value
     zero indicates delete immediately. If this value is nil, the default grace
     period will be used instead. The grace period is the duration in seconds
     after the processes running in the pod are sent a termination signal and
     the time when the processes are forcibly halted with a kill signal. Set
     this value longer than the expected cleanup time for your process. Defaults
     to 30 seconds.

   tolerations	<[]Object>
     If specified, the pod's tolerations.

   topologySpreadConstraints	<[]Object>
     TopologySpreadConstraints describes how a group of pods ought to spread
     across topology domains. Scheduler will schedule pods in a way which abides
     by the constraints. This field is only honored by clusters that enable the
     EvenPodsSpread feature. All topologySpreadConstraints are ANDed.

   volumes	<[]Object>
     List of volumes that can be mounted by containers belonging to the pod.
     More info: https://kubernetes.io/docs/concepts/storage/volumes

等等。

我们不可能在较短时间内记住这些命令和参数的用法，但是我们可以利用这些帮助信息快速去查询到怎么使用。

授人以鱼不如授人以渔。