CustomResourceDefinition（CRD）是 v1.7 + 新增的无需改变代码就可以扩展 Kubernetes API 的机制，用来管理自定义对象。它实际上是 ThirdPartyResources（TPR） 的升级版本，而 TPR 已经在 v1.8 中删除。
一些使用场景：
提供/管理外部数据存储/数据库(例如 CloudSQL/RDS 实例)
对k8s基础资源进行更高层次的抽象(比如定义一个etcd集群)
其实crd在很多k8s周边开源项目中有使用，比如ingress-controller和众多的operator
1. 目录结构
pkg
|--apis
|--samplecontroller
|--v1alpha1
|--doc.go
|--register.go
|--types.go
|--register.go
|--client
2. 配置Gopkg.toml:
配置完成后执行dep ensure -v 下载依赖
required = [
"k8s.io/code-generator/cmd/client-gen"
]
[[constraint]]
name = "k8s.io/client-go"
version = "v6.0.0"
[[constraint]]
name = "k8s.io/api"
version = "kubernetes-1.10.4"
[[constraint]]
name = "k8s.io/apimachinery"
version = "kubernetes-1.10.4"
[[constraint]]
name = "k8s.io/code-generator"
version = "kubernetes-1.10.4"
[prune]
non-go = true
go-tests = true
unused-packages = true
[[prune.project]]
name = "k8s.io/code-generator"
unused-packages = false
non-go = false
go-tests = false
[[prune.project]]
name = "k8s.io/gengo"
unused-packages = false
non-go = false
go-tests = false
3. 生成crd客户端代码
1.1 先编写 doc.go ，types.go ,register.go 代码
doc.go
// +k8s:deepcopy-gen=package
// Package v1alpha1 is the v1alpha1 version of the API.
// +groupName=samplecontroller.k8s.io
package v1alpha1
types.go
package v1alpha1
import (
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
)
// +genclient
// +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object
// Foo is a specification for a Foo resource
type Foo struct {
metav1.TypeMeta `json:",inline"`
metav1.ObjectMeta `json:"metadata,omitempty"`
Spec FooSpec `json:"spec"`
Status FooStatus `json:"status"`
}
// FooSpec is the spec for a Foo resource
type FooSpec struct {
DeploymentName string `json:"deploymentName"`
Replicas *int32 `json:"replicas"`
}
// FooStatus is the status for a Foo resource
type FooStatus struct {
AvailableReplicas int32 `json:"availableReplicas"`
}
// +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object
// FooList is a list of Foo resources
type FooList struct {
metav1.TypeMeta `json:",inline"`
metav1.ListMeta `json:"metadata"`
Items []Foo `json:"items"`
}
register.go
package v1alpha1
import (
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/runtime"
"k8s.io/apimachinery/pkg/runtime/schema"
samplecontroller "github.com/hidevopsio/hioak/pkg/apis/samplecontroller"
)
// SchemeGroupVersion is group version used to register these objects
var SchemeGroupVersion = schema.GroupVersion{Group: samplecontroller.GroupName, Version: "v1alpha1"}
// Kind takes an unqualified kind and returns back a Group qualified GroupKind
func Kind(kind string) schema.GroupKind {
return SchemeGroupVersion.WithKind(kind).GroupKind()
}
// Resource takes an unqualified resource and returns a Group qualified GroupResource
func Resource(resource string) schema.GroupResource {
return SchemeGroupVersion.WithResource(resource).GroupResource()
}
var (
SchemeBuilder = runtime.NewSchemeBuilder(addKnownTypes)
AddToScheme = SchemeBuilder.AddToScheme
)
// Adds the list of known types to Scheme.
func addKnownTypes(scheme *runtime.Scheme) error {
scheme.AddKnownTypes(SchemeGroupVersion,
&Foo{},
&FooList{},
)
metav1.AddToGroupVersion(scheme, SchemeGroupVersion)
return nil
}
register.go(此文件是在samplecontroller目录下)
package samplecontroller
const (
GroupName = "samplecontroller.k8s.io"
)
1.2 执行生成代码的命令
- 1.进入project目录
GOPATH/src/github.com/openshift-evangelists/crd-code-generation/vendor/k8s.io/code-generator
- 2.给generate-groups.sh 添加执行权限 $chmod +x generate-groups.sh
- 3.在当前目录执行以下命令
./generate-groups.sh all \
github.com/hidevopsio/hioak/pkg/client \
github.com/hidevopsio/hioak/pkg/apis \
samplecontroller:v1alpha1
四个参数：
- 第一个 参数：all, 是说，要生成所有的模块，如clientset,informers,listers等
- 第二个参数：github.com/hidevopsio/hioak/pkg/client 这个是你要生成代码的目录，目录的名称是client, 也有叫generated的
- 第三个参数：github.com/hidevopsio/hioak/pkg/apis 这个目录就是你自己创建的，里面至少包括types.go那个目录
- 第四个参数："samplecontroller:v1alpha1"： 这个就是目录，samplecontroller是apis下的目录，v1beta1是samplecontroller下面的目录
运行generate-groups.sh后，会在gopath目录的bin目录下，生成5个工具，如client-gen,deepcopy-gen等
就是利用这几个工具，来生成代码的
生成代码可能遇到的问题:
1.提示 ./generate-groups.sh: line 65: /Users/mac/.gvm/pkgsets/go1.10/vpcloud:/Users/mac/.gvm/pkgsets/go1.10/global/bin/deepcopy-gen: No such file or directory
原因是我的GOPATH有两个目录，脚本默认是获取GOPATH对应的字符串未路径
解决方法:export GOPATH=/Users/mac/.gvm/pkgsets/go1.10/vpcloud
如果还是此类报错就要按照提示进入deepcopy-gen所在目录，查看deepcopy-gen是否存在并执行deepcopy-gen 来分析更加精准的异常
1.3代码生成后的目录结构
pkg
|--apis
|--samplecontroller
|--v1alpha1
|--doc.go
|--register.go
|--types.go
|--zz_generated.deepcopy.go
|--register.go
|--client
|--clientset
|--informers
|--listers
4. 使用生成的代码
4.1 创建FOO类型的crd及使用
kubectl create -f crd.yaml
crd.yaml:
apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
name: foos.samplecontroller.k8s.io
spec:
group: samplecontroller.k8s.io
version: v1alpha1
names:
kind: Foo
plural: foos
scope: Namespaced
kubectl create -f example-foo.yaml
example-foo.yaml:
apiVersion: samplecontroller.k8s.io/v1alpha1
kind: Foo
metadata:
name: example-foo
spec:
deploymentName: example-foo
replicas: 1
4.2 创建一个main.go 文件直接使用
main.go
package main
import (
"flag"
"fmt"
"github.com/golang/glog"
clientset "hidevops.io/sample-controller/pkg/client/clientset/versioned"
"k8s.io/client-go/tools/clientcmd"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
)
var (
masterURL string
kubeconfig string
)
func init() {
flag.StringVar(&kubeconfig, "kubeconfig", "/Users/mac/.kube/config", "Path to a kubeconfig. Only required if out-of-cluster.")
flag.StringVar(&masterURL, "master", "", "The address of the Kubernetes API server. Overrides any value in kubeconfig. Only required if out-of-cluster.")
}
func main() {
flag.Parse()
cfg, err := clientcmd.BuildConfigFromFlags(masterURL, kubeconfig)
if err != nil {
glog.Fatalf("Error building kubeconfig: %s", err.Error())
}
exampleClient, err := clientset.NewForConfig(cfg)
if err != nil {
glog.Fatalf("Error building example clientset: %s", err.Error())
}
fooList,err := exampleClient.SamplecontrollerV1alpha1().Foos("defaule").List(metav1.ListOptions{})
if err != nil {
fmt.Printf("Error %v",err)
return
}
fmt.Println("fooList ",fooList)
}
参考资料:
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