explain¶
我们可以通过编写一个yaml的配置清单来创建一个内容丰富的对象，而各种对象的都有些什么字段呢？ 也就是都有哪些属性呢？我们可以通过explain来查看
查看pod有哪些字段¶
[alvin@k8s1 ~]$ kubectl explain pods
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/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/api-conventions.md#types-kinds
metadata <Object>
Standard object's metadata. More info:
https://git.k8s.io/community/contributors/devel/api-conventions.md#metadata
spec <Object>
Specification of the desired behavior of the pod. More info:
https://git.k8s.io/community/contributors/devel/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/api-conventions.md#spec-and-status
查看pod下的metadata有哪些字段¶
那么如果我们想知道pod里的metadata又有哪些字段呢？那么我们可以进行如下操作
[alvin@k8s1 ~]$ kubectl explain pods.metadata
KIND: Pod
VERSION: v1
RESOURCE: metadata <Object>
DESCRIPTION:
Standard object's metadata. More info:
https://git.k8s.io/community/contributors/devel/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/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/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.
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/api-conventions.md#idempotency
generation <integer>
A sequence number representing a specific generation of the desired state.
Populated by the system. Read-only.
initializers <Object>
An initializer is a controller which enforces some system invariant at
object creation time. This field is a list of initializers that have not
yet acted on this object. If nil or empty, this object has been completely
initialized. Otherwise, the object is considered uninitialized and is
hidden (in list/watch and get calls) from clients that haven't explicitly
asked to observe uninitialized objects. When an object is created, the
system will populate this list with the current set of initializers. Only
privileged users may set or modify this list. Once it is empty, it may not
be modified further by any user.
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
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/api-conventions.md#concurrency-control-and-consistency
selfLink <string>
SelfLink is a URL representing this object. Populated by the system.
Read-only.
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
[alvin@k8s1 ~]$
查看更深的字段，如pods.spec.containers.livenessProbe¶
那如果是更深一点的字段呢？ 比如pods.spec.containers.livenessProbe
[alvin@k8s1 ~]$ kubectl explain pods.spec.containers.livenessProbe
KIND: Pod
VERSION: v1
RESOURCE: livenessProbe <Object>
DESCRIPTION:
Periodic probe of container liveness. Container will be restarted if the
probe fails. Cannot be updated. More info:
https://kubernetes.io/docs/concepts/workloads/pods/pod-lifecycle#container-probes
Probe describes a health check to be performed against a container to
determine whether it is alive or ready to receive traffic.
FIELDS:
exec <Object>
One and only one of the following should be specified. Exec specifies the
action to take.
failureThreshold <integer>
Minimum consecutive failures for the probe to be considered failed after
having succeeded. Defaults to 3. Minimum value is 1.
httpGet <Object>
HTTPGet specifies the http request to perform.
initialDelaySeconds <integer>
Number of seconds after the container has started before liveness probes
are initiated. More info:
https://kubernetes.io/docs/concepts/workloads/pods/pod-lifecycle#container-probes
periodSeconds <integer>
How often (in seconds) to perform the probe. Default to 10 seconds. Minimum
value is 1.
successThreshold <integer>
Minimum consecutive successes for the probe to be considered successful
after having failed. Defaults to 1. Must be 1 for liveness. Minimum value
is 1.
tcpSocket <Object>
TCPSocket specifies an action involving a TCP port. TCP hooks not yet
supported
timeoutSeconds <integer>
Number of seconds after which the probe times out. Defaults to 1 second.
Minimum value is 1. More info:
https://kubernetes.io/docs/concepts/workloads/pods/pod-lifecycle#container-probes