编写Kubernetes中编写yaml文件,Pod模板详解
K8s的yaml文件功能十分强大,对于新手来说,想要快速照掌握且灵活运用就显得有些困难。下文将给出Pod模板常用的一些代码及解释,如何快速运用。
Pod中 yaml 的详解
注意:都是以两个空格为递进,而非tab
apiVersion: v1
kind: Pod
metadata:
name: string
namespace: string
labels:
- name: string
spec:
containers:
- name: string
image: string
imagePullPolicy: [ Always| Never| IfNotPresent ]
command: [string]
args: [string]
workingDir: string
volumeMounts:
- name: string
mountPath: string
readOnly: boolean
volumes:
- name: string
emptyDir: { }
hostPath: string
path: string
secret:
scretname: string
items:
- key: string
path: string
configMap:
name: string
items:
- key: string
path: string
ports:
- name: string
containerPort: int
hostPort: int
protocol: string
env:
- name: string
value: string
resources:
limits:
cpu: string
memory: string
requests:
cpu: string
memory: string
lifecycle:
postStart:
preStop:
livenessProbe:
exec:
command: [string]
initialDelaySeconds
timeoutSeconds
periodSeconds
failureThreshold
successThreshold
httpGet:
path: string
port: number
host: string
scheme: string
HttpHeaders:
- name: string
value: string
tcpSocket:
port: number
initialDelaySeconds: 0
timeoutSeconds: 0
periodSeconds: 0
successThreshold: 0
failureThreshold: 0
securityContext:
privileged: false
restartPolicy: [Always | Never | OnFailure]
nodeName:
nodeSelector: obeject
imagePullSecrets:
- name: string
hostNetwork: false
在编写yaml的时候,可结合帮助,灵活运用,找到所需的那个代码。 k8s查看yaml文件帮助的命令
构建pod,ns,rs,rc等等,只需在后面加上即可出现对应模板
kubectl explain pod/ns/rs/rc/networkpolicy/hpa
以pod为例
以pod为例
[ root@master ~]
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
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
metadata < Object>
Standard object's metadata. More info:
https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md
spec < Object>
Specification of the desired behavior of the pod. More info:
https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md
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
逐层往下查看
以pod中的spec为例 它会给出spec下的所有可写的代码,可以 . 为分隔符依此往下查阅
[root@master ~]
KIND: Pod
VERSION: v1
RESOURCE: spec
DESCRIPTION:
Specification of the desired behavior of the pod. More info:
https:/ / git. k8s. io/ community/ contributors/ devel/ sig- architecture/ api- conventions. md
PodSpec is a description of a pod.
FIELDS:
activeDeadlineSeconds
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
If specified, the pod's scheduling constraints
automountServiceAccountToken
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
Specifies the DNS parameters of a pod. Parameters specified here will be
merged to the generated DNS configuration based on DNSPolicy.
dnsPolicy
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
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
Use the host's ipc namespace. Optional: Default to false.
hostNetwork
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
Use the host's pid namespace. Optional: Default to false.
hostname
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
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
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 [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
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
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
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
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
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/
runtimeClassName
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
If specified, the pod will be dispatched by specified scheduler. If not
specified, the pod will be dispatched by default scheduler.
securityContext
SecurityContext holds pod- level security attributes and common container
settings. Optional: Defaults to empty. See type description for default
values of each field.
serviceAccount
DeprecatedServiceAccount is a depreciated alias for ServiceAccountName.
Deprecated: Use serviceAccountName instead.
serviceAccountName
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
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
If specified, the fully qualified Pod hostname will be
"...svc." . If not
specified, the pod will not have a domainname at all.
terminationGracePeriodSeconds
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
例1
yaml中的实战pod案例,先写个简单的
使用该yaml文件创建Pod要求如下: 1.Pod名称:nginx-pod; 2.使用:nginx 镜像; 3.拉取策略为:IfNotPresent; 4.容器名称:mynginx; 5.容器端口:80
其yaml文件如下
[ root@master ~]
apiVersion : v1
kind : Pod
metadata :
name : nginx- pod
spec :
containers :
- name : mynginx
image : nginx: latest
imagePullPolicy : IfNotPresent
ports :
- containerPort : 80
将其启动,且访问一下,试看是否能够访问到nginx首页
启动编写好的yaml文件
[root@master ~]
pod/ nginx- pod created
查看pod列表
[root@master ~]
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx- pod 1/ 1 Running 0 28s 10. 244. 1. 21 node
访问pod
[root@master ~]
<! DOCTYPE html>
Welcome to nginx! </ title>