kubernetes自定義資源對象再極大程度提升了API Server的可擴展性,讓企業可以根據業務需求經過CRD編寫controller或者operator來實現生產中各類特殊場景。隨着k8s的版本升級,CRD的功能也愈來愈完善,下面對其中幾點進行說明。html
如下驗證kubernetes版本爲1.13.2,docker版本:18.09.5前端
在項目中用自定義資源對象時,若是建立自定義資源時某些字段不符合要求,會致使監聽該資源對象的controller或者operator出現異常,解析結構體報錯,因此Validation這個功能很是實用,在建立時就進行校驗,減小後面的排錯和異常處理的麻煩。java
能夠經過 OpenAPI v3 schema驗證自定義對象是否符合標準 。此外,如下限制適用於 schema:node
default
、nullable
、discriminator
、readOnly
、writeOnly
、xml
、 deprecated
和 $ref
不能設置。 uniqueItems
不能設置爲 true。 additionalProperties
不能設置爲 false。 可使用 kube-apiserverCustomResourceValidation
上的功能門(feature gate)禁用此功能:python
--feature-gates=CustomResourceValidation=false複製代碼
從如下特性門參數說明地址,能夠看到Validation功能在k8s 1.8版本就已經有了,可是CustomResourceValidation特性門是默認false,1.9Beta以後版本默認爲truegit
如下示例將大概對該功能進行應用和說明,在如下示例中,CustomResourceDefinition 對自定義對象應用如下驗證:github
spec.replicas
爲必填項,類型爲integer,值爲大於等於0小於50的偶數(2的倍數); spec.repository
爲必填項; spec.version
爲必填項; spec.pause
爲boolean類型; spec.updateStrategy
爲object類型,該object中有type、pipeline、assignStrategies屬性; spec.updateStrategy.type
爲string類型,並且只能爲"AssignReceive", "AutoReceive"兩個枚舉值; spec.updateStrategy.pipeline
爲string類型,並且爲正整數的字符串,符合正則表達式^([1-9][0-9]*){1,3}$
; spec.updateStrategy.assignStrategies
爲array類型,其元素爲object類型(包含slots和fromReplicas屬性); spec.updateStrategy.assignStrategies.slots
爲1-16384的正整數; spec.updateStrategy.assignStrategies.fromReplicas
爲字符串,符合正則表達式^[a-z0-9,]{3,}$
,即至少匹配3位a-z或者0-9或者逗號的字符串; spec.pod
爲array類型,其元素爲object類型(包含configmap、monitorImage、initImage、middlewareImage字段); spec.pod.configmap
、spec.pod.monitorImage
、spec.pod.initImage
、spec.pod.middlewareImage
爲string類型;且用required指定configmap、initImage、middlewareImage字段爲必填項。 將如下內容保存到 redis-cluster-crd.yaml
:golang
apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
name: redisclusters.redis.middleware.hc.cn
spec:
group: redis.middleware.hc.cn
versions:
- name: v1alpha1
# Each version can be enabled/disabled by Served flag.
served: true
# One and only one version must be marked as the storage version.
storage: true
scope: Namespaced
names:
kind: RedisCluster
singular: rediscluster
listKind: RedisClusterList
plural: redisclusters
shortNames:
- rec
# 執行kubectl get all時會查到pod、service、該crd等屬於all categories的資源對象
categories:
- all
validation:
# openAPIV3Schema 適用於驗證自定義對象的 schema。
openAPIV3Schema:
properties:
spec:
required: ["replicas", "repository", "version"]
properties:
pause:
type: boolean
replicas:
type: integer
minimum: 0
maximum: 50
# 偶數
multipleOf: 2
updateStrategy:
type: object
properties:
type:
type: string
# 枚舉
enum: ["AssignReceive", "AutoReceive"]
pipeline:
type: string
pattern: '^([1-9][0-9]*){1,3}$'
assignStrategies:
type: array
items:
type: object
properties:
slots:
type: integer
minimum: 1
maximum: 16384
fromReplicas:
type: string
# 至少匹配3位,a-z或者0-9或者,
pattern: '^[a-z0-9,]{3,}$'
pod:
type: array
items:
type: object
required: ["configmap", "middlewareImage", "initImage"]
properties:
configmap:
type: string
monitorImage:
type: string
initImage:
type: string
middlewareImage:
type: string複製代碼
建立它:面試
kubectl create -f redis-cluster-crd.yaml複製代碼
默認不加validation時,在建立自定義資源對象時,不會校驗,有些字段沒有了(如spec.replicas
)均可以正常被建立,爲了減小排錯的難度和operator、controller的麻煩的檢驗,因此在建立自定義資源定義時,就把validation加上。以上的檢驗應該覆蓋到了常見的檢驗場景,其餘場景能夠本身摸索。具體還能夠參考kubernetes源碼,1.13.2版本kubernetes源碼位於types.go第327行CustomResourceValidation結構體:正則表達式
$GOPATH/src/k8s.io/kubernetes/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/types.go複製代碼
將如下YAML保存到redis-cluster-cr.yaml
:
apiVersion: redis.middleware.hc.cn/v1alpha1
kind: RedisCluster
metadata:
name: example000-redis-cluster
namespace: kube-system
spec:
# 表明redis集羣的個數
replicas: 3
# 表明是否進入維修狀態
pause: true
repository: library/redis
# 鏡像版本,便於後續多版本特化支持
version: 3.2.6
#redis集羣升級策略
updateStrategy:
# 升級類型爲AutoReceive(自動分配,不用AssignStrategies), AssignReceive(指定值分配,須要用AssignStrategies)
type: AssignReceive1
pipeline: "100a"
assignStrategies:
-
slots: 0
fromReplicas: nodeId1
-
# 從nodeId3,nodeId4一共分配1000個卡槽
slots: 1000
# 多個nodeId用逗號分隔
fromReplicas: nodeId3,nodeId4
# redis 實例配置詳情
pod:
# 配置文件模板名
- configmap: example000-redis-cluster-config
# 監控鏡像
monitorImage: redis-exporter:v1
# 初始化鏡像
#initImage: redis-init:v1
# 中間件容器鏡像
middlewareImage: redis-trib:3.2.6複製代碼
並建立它:
kubectl create -f redis-cluster-cr.yaml複製代碼
會發現報如下錯誤:
# kubectl apply -f redis-cluster-cr.yaml
The RedisCluster "example000-redis-cluster" is invalid: []: Invalid value: map[string]interface {}{"apiVersion":"redis.middleware.hc.cn/v1alpha1", "kind":"RedisCluster", "metadata":map[string]interface {}{"namespace":"kube-system", "uid":"b0946031-766b-11e9-b457-000c295db389", "resourceVersion":"44231", "generation":19, "creationTimestamp":"2019-05-14T17:14:10Z", "annotations":map[string]interface {}{"kubectl.kubernetes.io/last-applied-configuration":"{\"apiVersion\":\"redis.middleware.hc.cn/v1alpha1\",\"kind\":\"RedisCluster\",\"metadata\":{\"annotations\":{},\"name\":\"example000-redis-cluster\",\"namespace\":\"kube-system\"},\"spec\":{\"pause\":true,\"pod\":[{\"configmap\":\"example000-redis-cluster-config\",\"middlewareImage\":\"redis-trib:3.2.6\",\"monitorImage\":\"redis-exporter:v1\"}],\"replicas\":3,\"repository\":\"library/redis\",\"updateStrategy\":{\"assignStrategies\":[{\"fromReplicas\":\"nodeId1\",\"slots\":0},{\"fromReplicas\":\"nodeId3,nodeId4\",\"slots\":1000}],\"pipeline\":\"100a\",\"type\":\"AssignReceive1\"},\"version\":\"3.2.6\"}}\n"}, "name":"example000-redis-cluster"}, "spec":map[string]interface {}{"version":"3.2.6", "pause":true, "pod":[]interface {}{map[string]interface {}{"middlewareImage":"redis-trib:3.2.6", "monitorImage":"redis-exporter:v1", "configmap":"example000-redis-cluster-config"}}, "replicas":3, "repository":"library/redis", "updateStrategy":map[string]interface {}{"assignStrategies":[]interface {}{map[string]interface {}{"fromReplicas":"nodeId1", "slots":0}, map[string]interface {}{"fromReplicas":"nodeId3,nodeId4", "slots":1000}}, "pipeline":"100a", "type":"AssignReceive1"}}}: validation failure list:
spec.updateStrategy.assignStrategies.fromReplicas in body should match '^[a-z0-9,]{3,}$'
spec.updateStrategy.assignStrategies.slots in body should be greater than or equal to 1
spec.updateStrategy.pipeline in body should match '^([1-9][0-9]*){1,3}$'
spec.updateStrategy.type in body should be one of [AssignReceive AutoReceive]
spec.pod.initImage in body is required
spec.replicas in body should be a multiple of 2複製代碼
若是全部字段都符合校驗邏輯,才能夠建立對象。
將如下 YAML 保存到 redis-cluster-cr.yaml
:
apiVersion: redis.middleware.hc.cn/v1alpha1
kind: RedisCluster
metadata:
name: example000-redis-cluster
namespace: kube-system
spec:
# 表明redis集羣的個數
replicas: 6
# 表明是否進入維修狀態
pause: true
repository: library/redis
# 鏡像版本,便於後續多版本特化支持
version: 3.2.6
#redis集羣升級策略
updateStrategy:
# 升級類型爲AutoReceive(自動分配,不用AssignStrategies), AssignReceive(指定值分配,須要用AssignStrategies)
type: AssignReceive
pipeline: "100"
assignStrategies:
-
slots: 1
fromReplicas: all
-
# 從nodeId3,nodeId4一共分配1000個卡槽
slots: 1000
# 多個nodeId用逗號分隔
fromReplicas: node1,node2
# redis 實例配置詳情
pod:
# 配置文件模板名
- configmap: example000-redis-cluster-config
# 監控鏡像
monitorImage: redis-exporter:v1
# 初始化鏡像
initImage: redis-init:v1
# 中間件容器鏡像
middlewareImage: redis-trib:3.2.6複製代碼
並建立它,發現才能夠建立:
# kubectl apply -f redis-cluster-cr.yaml
rediscluster.redis.middleware.hc.cn/example000-redis-cluster configured複製代碼
類別是自定義資源所屬的分組資源的列表(例如 all
)。您可使用 kubectl get
列出屬於該類別的資源。此功能可用於 v1.10 及以上k8s版本自定義資源。
如下示例添加 all
CustomResourceDefinition 中的類別列表,並說明如何使用 kubectl get all
輸出自定義資源 。
將如下 內容保存到 redis-cluster-crd.yaml
中執行kubectl apply -f redis-cluster-crd.yaml
:
apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
name: redisclusters.redis.middleware.hc.cn
spec:
group: redis.middleware.hc.cn
versions:
- name: v1alpha1
# Each version can be enabled/disabled by Served flag.
served: true
# One and only one version must be marked as the storage version.
storage: true
scope: Namespaced
names:
kind: RedisCluster
singular: rediscluster
listKind: RedisClusterList
plural: redisclusters
shortNames:
- rec
# 執行kubectl get all時會查到pod、service、該crd等屬於all categories的資源對象
categories:
- all複製代碼
將如下內容保存到redis-cluster-cr.yaml
中執行kubectl apply -f redis-cluster-cr.yaml
:
apiVersion: redis.middleware.hc.cn/v1alpha1
kind: RedisCluster
metadata:
name: example000-redis-cluster
namespace: kube-system
spec:
# 表明redis集羣的個數
replicas: 6
# 表明是否進入維修狀態
pause: true
repository: library/redis
# 鏡像版本,便於後續多版本特化支持
version: 3.2.6
#redis集羣升級策略
updateStrategy:
# 升級類型爲AutoReceive(自動分配,不用AssignStrategies), AssignReceive(指定值分配,須要用AssignStrategies)
type: AssignReceive
pipeline: "100"
assignStrategies:
-
slots: 2000
fromReplicas: nodeId1
-
# 從nodeId3,nodeId4一共分配1000個卡槽
slots: 1000
# 多個nodeId用逗號分隔
fromReplicas: nodeId3,nodeId4
# redis 實例配置詳情
pod:
# 配置文件模板名
- configmap: example000-redis-cluster-config
# 監控鏡像
monitorImage: redis-exporter:v1
# 初始化鏡像
initImage: redis-init:v1
# 中間件容器鏡像
middlewareImage: redis-trib:3.2.6複製代碼
執行kubectl get all時會查到pod、service、該crd等屬於all categories的資源對象。(這個可能得等幾分鐘才能生效)
啓用狀態子資源後,將公開自定義資源的子資源 /status
。
.status
和 .spec
JSONPath 表示。 PUT /status
對子資源的請求採用自定義資源對象,並忽略除狀態節以外的任何更改。 PUT /status
對子資源的請求僅驗證自定義資源的狀態節。 PUT/ POST/ PATCH
請求自定義資源忽略更改狀態節。 .metadata.generation
的值。 在code-generator生成代碼時會生成,以下方法:
// RedisClusterInterface has methods to work with RedisCluster resources.
type RedisClusterInterface interface {
Create(*v1alpha1.RedisCluster) (*v1alpha1.RedisCluster, error)
Update(*v1alpha1.RedisCluster) (*v1alpha1.RedisCluster, error)
UpdateStatus(*v1alpha1.RedisCluster) (*v1alpha1.RedisCluster, error)
......
}複製代碼
啓用 scale 子資源後,將公開自定義資源的子資源 /scale
。該 autoscaling/v1.Scale 對象做爲有效負載發送 /scale。
要啓用 scale 子資源,CustomResourceDefinition 中須要定義如下值。
在如下示例中,啓用了status 和 scale 子資源。
將如下內容保存到redis-cluster-crd.yaml
並建立 kubectl apply -f redis-cluster-crd.yaml
:
apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
name: redisclusters.redis.middleware.hc.cn
spec:
group: redis.middleware.hc.cn
versions:
- name: v1alpha1
# Each version can be enabled/disabled by Served flag.
served: true
# One and only one version must be marked as the storage version.
storage: true
scope: Namespaced
names:
kind: RedisCluster
singular: rediscluster
listKind: RedisClusterList
plural: redisclusters
shortNames:
- rec
# 執行kubectl get all時會查到pod、service、該crd等屬於all categories的資源對象
categories:
- all
subresources:
# status enables the status subresource.
status: {}
scale:
# specReplicasPath defines the JSONPath inside of a custom resource that corresponds to Scale.Spec.Replicas.
specReplicasPath: .spec.replicas
# statusReplicasPath defines the JSONPath inside of a custom resource that corresponds to Scale.Status.Replicas.
statusReplicasPath: .status.replicas
# labelSelectorPath defines the JSONPath inside of a custom resource that corresponds to Scale.Status.Selector.
labelSelectorPath: .status.labelSelector複製代碼
建立 CustomResourceDefinition 對象後,您能夠建立自定義對象。
若是您將如下 YAML 保存到 redis-cluster-cr.yaml
:
apiVersion: redis.middleware.hc.cn/v1alpha1
kind: RedisCluster
metadata:
name: example000-redis-cluster
namespace: kube-system
spec:
# 表明redis集羣的個數
replicas: 6
# 表明是否進入維修狀態
pause: true
repository: library/redis
# 鏡像版本,便於後續多版本特化支持
version: 3.2.6
#redis集羣升級策略
updateStrategy:
# 升級類型爲AutoReceive(自動分配,不用AssignStrategies), AssignReceive(指定值分配,須要用AssignStrategies)
type: AssignReceive
pipeline: "100"
assignStrategies:
-
slots: 2000
fromReplicas: nodeId1
-
# 從nodeId3,nodeId4一共分配1000個卡槽
slots: 1000
# 多個nodeId用逗號分隔
fromReplicas: nodeId3,nodeId4
# redis 實例配置詳情
pod:
# 配置文件模板名
- configmap: example000-redis-cluster-config
# 監控鏡像
monitorImage: redis-exporter:v1
# 初始化鏡像
initImage: redis-init:v1
# 中間件容器鏡像
middlewareImage: redis-trib:3.2.6複製代碼
並建立它:
kubectl create -f redis-cluster-cr.yaml複製代碼
而後在如下位置建立新的命名空間 RESTful API 端點:
/apis/redis.middleware.hc.cn/v1alpha1/namespaces/kube-system/redisclusters/example000-redis-cluster/status複製代碼
和
/apis/redis.middleware.hc.cn/v1alpha1/namespaces/kube-system/redisclusters/example000-redis-cluster/scale複製代碼
可使用該 kubectl scale
命令縮放自定義資源。例如,以上建立的自定義資源的的 .spec.replicas
設置爲 10:
# kubectl get rec --all-namespaces
NAMESPACE NAME DESIRED PAUSE AGE
kube-system example000-redis-cluster 6 true 10h
# kubectl scale --replicas=10 rec/example000-redis-cluster -nkube-system
rediscluster.redis.middleware.hc.cn/example000-redis-cluster scaled
# kubectl get rec --all-namespaces
NAMESPACE NAME DESIRED PAUSE AGE
kube-system example000-redis-cluster 10 true 10h
# kubectl get rec example000-redis-cluster -n kube-system -o jsonpath='{.spec.replicas}'
10複製代碼
從 Kubernetes 1.11 開始,kubectl 使用服務器端打印。服務器決定 kubectl get
命令顯示哪些列。您可使用 CustomResourceDefinition 自定義這些列。下面的示例將輸出 Spec
、Replicas
和 Age
列。
redis-cluster-crd.yaml
。 apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
name: redisclusters.redis.middleware.hc.cn
spec:
group: redis.middleware.hc.cn
versions:
- name: v1alpha1
# Each version can be enabled/disabled by Served flag.
served: true
# One and only one version must be marked as the storage version.
storage: true
scope: Namespaced
names:
kind: RedisCluster
singular: rediscluster
listKind: RedisClusterList
plural: redisclusters
shortNames:
- rec
# 執行kubectl get all時會查到pod、service、該crd等屬於all categories的資源對象
categories:
- all
additionalPrinterColumns:
- name: DESIRED
type: integer
description: The number of statefulset managed by the this redisCluster
JSONPath: .spec.replicas
# boolean,date,integer,number,string
- name: PAUSE
type: boolean
description: Whether this redisCluster's grandson (pod) will not be managed by statefulset
JSONPath: .spec.pause複製代碼
kubectl create -f redis-cluster-crd.yaml複製代碼
redis-cluster-cr.yaml
實例。 kubectl get rec --all-namespaces複製代碼
請注意 NAME
、NAMESPACE
, DESIRED
、PAUSE
和 AGE
在輸出列,而且都被轉成了大寫字母:
[root@master-192 redis-container]# kubectl get rec --all-namespaces
NAMESPACE NAME DESIRED PAUSE AGE
kube-system example000-redis-cluster 6 true 10h複製代碼
NAME
和NAMESPACE
列是隱含的,不須要在 CustomResourceDefinition 中定義。
在golang編寫的operator代碼中建立該結構體:
//建立CRD
func CreateRedisClusterCRD(extensionCRClient *extensionsclient.Clientset) error {
//add CustomResourceValidation due to guarantee redis operator work normally
labelSelectorPath := ".status.labelSelector"
replicasMinimum := float64(0)
replicasMaximum := float64(50)
replicasMultipleOf := float64(2)
slotsMinimum := float64(1)
slotsMaximum := float64(16384)
assignStr := "AssignReceive"
autoStr := "AutoReceive"
assignJson, _ := json.Marshal(assignStr)
autoJson, _ := json.Marshal(autoStr)
crd := &v1beta1.CustomResourceDefinition{
ObjectMeta: metav1.ObjectMeta{
Name: "redisclusters." + v1alpha1.SchemeGroupVersion.Group,
},
Spec: v1beta1.CustomResourceDefinitionSpec{
Group: v1alpha1.SchemeGroupVersion.Group,
Versions: []v1beta1.CustomResourceDefinitionVersion {
{
// Served is a flag enabling/disabling this version from being served via REST APIs
Served: true,
Name: v1alpha1.SchemeGroupVersion.Version,
// Storage flags the version as storage version. There must be exactly one flagged as storage version
Storage: true,
},
},
Scope: v1beta1.NamespaceScoped,
Names: v1beta1.CustomResourceDefinitionNames{
Kind: "RedisCluster",
ListKind: "RedisClusterList",
Plural: "redisclusters",
Singular: "rediscluster",
ShortNames: []string{"rec"},
Categories: []string{"all"},
},
Subresources: &v1beta1.CustomResourceSubresources {
Status: &v1beta1.CustomResourceSubresourceStatus {},
Scale: &v1beta1.CustomResourceSubresourceScale {
SpecReplicasPath: ".spec.replicas",
StatusReplicasPath: ".status.replicas",
LabelSelectorPath: &labelSelectorPath,
},
},
AdditionalPrinterColumns: []v1beta1.CustomResourceColumnDefinition{
{
Name: "DESIRED",
Type: "integer",
Description: "The number of statefulset managed by the this redisCluster",
JSONPath: ".spec.replicas",
},
{
Name: "PAUSE",
Type: "boolean",
Description: "Whether this redisCluster's grandson (pod) will not be managed by statefulset",
JSONPath: ".spec.pause",
},
{
Name: "AGE",
Type: "date",
JSONPath: ".metadata.creationTimestamp",
},
},
Validation: &v1beta1.CustomResourceValidation {
OpenAPIV3Schema: &v1beta1.JSONSchemaProps {
Properties: map[string]v1beta1.JSONSchemaProps {
"spec": {
Required: []string{"replicas", "repository", "version"},
Properties: map[string]v1beta1.JSONSchemaProps{
"pause": {
Type: "boolean",
},
"replicas": {
Type: "integer",
Minimum: &replicasMinimum,
Maximum: &replicasMaximum,
MultipleOf: &replicasMultipleOf,
},
"updateStrategy": {
Type: "object",
Properties: map[string]v1beta1.JSONSchemaProps{
"type": {
Type: "string",
Enum: []v1beta1.JSON {
{
//這裏必須是JSON格式的字符串
Raw: assignJson,
},
{
Raw: autoJson,
},
},
},
"pipeline": {
Type: "string",
Pattern: `^([1-9][0-9]*){1,3}$`,
},
"assignStrategies": {
Type: "array",
Items: &v1beta1.JSONSchemaPropsOrArray{
Schema: &v1beta1.JSONSchemaProps{
Type: "object",
Properties: map[string]v1beta1.JSONSchemaProps{
"slots": {
Type: "integer",
Minimum: &slotsMinimum,
Maximum: &slotsMaximum,
},
"fromReplicas": {
Type: "string",
Pattern: `^[a-z0-9,]{3,}$`,
},
},
},
},
},
},
},
},
},
"pod": {
Type: "array",
Items: &v1beta1.JSONSchemaPropsOrArray {
Schema: &v1beta1.JSONSchemaProps {
Type: "object",
Required: []string{"replicas", "repository", "version"},
Properties: map[string]v1beta1.JSONSchemaProps{
"configmap": {
Type: "string",
},
"monitorImage": {
Type: "string",
},
"initImage": {
Type: "string",
},
"middlewareImage": {
Type: "string",
},
},
},
},
},
},
},
},
},
}
_, err := extensionCRClient.ApiextensionsV1beta1().CustomResourceDefinitions().Create(crd)
return err
}
複製代碼
官方Extend the Kubernetes API with CustomResourceDefinitions:
https://kubernetes.io/docs/tasks/access-kubernetes-api/custom-resources/custom-resource-definitions/
feature-gates參數說明:
https://kubernetes.io/docs/reference/command-line-tools-reference/feature-gates/
CustomResourceDefinition中文文檔:
https://kubernetes.feisky.xyz/cha-jian-kuo-zhan/api/customresourcedefinition
swagger和openAPI: 數據類型:
https://www.breakyizhan.com/swagger/2969.html
正則表達式:
https://www.cnblogs.com/afarmer/archive/2011/08/29/2158860.html
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