简单的controller

也可以参考官方的sample：https://github.com/kubernetes/sample-controller

实现步骤

1.向k8s集群提交CRD模板和其实例化对象，使k8s能识别

1 官方文档了解下CRD 
https://kubernetes.io/docs/tasks/access-kubernetes-api/custom-resources/custom-resource-definitions/#create-a-customresourcedefinition
2 登录可以执行kubectl命令的机器，创建student.yaml文件
[root@localhost student]# kubectl apply -f student.yaml
customresourcedefinition.apiextensions.k8s.io/students.stable.k8s.io created
[root@localhost student]# kubectl get crd
NAME                          CREATED AT
crontabs.stable.example.com   2019-03-26T01:48:32Z
students.stable.k8s.io        2019-04-12T02:42:08Z
3 通过模板student.yaml来实例一个Student对象，创建test1.yaml，同理实例test2.yaml
[root@localhost student]# kubectl apply -f test1.yaml
student.stable.k8s.io/test1 created
4 kubectl describe std test1

2.自动生成代码前的准备工作

1 在samplecontroller目录下新建目录，并添加以下文件
[root@localhost studentcontroller]# tree pkg
pkg
├── apis
│   └── stable
│       ├── register.go
│       └── v1
│           ├── doc.go
│           ├── register.go
│           ├── types.go
主要是为代码生成工具准备好资源对象的声明和注册接口
2 下载依赖
go get -u k8s.io/apimachinery/pkg/apis/meta/v1
go get -u k8s.io/code-generator/...

3.自动生成Client、Informer、WorkQueue相关的代码

[root@localhost code-generator]# export GOPATH=/root/mygolang
[root@localhost code-generator]# ./generate-groups.sh all "github.com/gfandada/samplecontroller/pkg/client" "github.com/gfandada/samplecontroller/pkg/apis" "stable:v1"
Generating deepcopy funcs
Generating clientset for stable:v1 at github.com/gfandada/samplecontroller/pkg/client/clientset
Generating listers for stable:v1 at github.com/gfandada/samplecontroller/pkg/client/listers
Generating informers for stable:v1 at github.com/gfandada/samplecontroller/pkg/client/informers
[root@localhost samplecontroller]# tree pkg
pkg
├── apis
│   └── stable
│       ├── register.go
│       └── v1
│           ├── doc.go
│           ├── register.go
│           ├── types.go
│           └── zz_generated.deepcopy.go
├── client
│   ├── clientset
│   │   └── versioned
│   │       ├── clientset.go
│   │       ├── doc.go
│   │       ├── fake
│   │       │   ├── clientset_generated.go
│   │       │   ├── doc.go
│   │       │   └── register.go
│   │       ├── scheme
│   │       │   ├── doc.go
│   │       │   └── register.go
│   │       └── typed
│   │           └── stable
│   │               └── v1
│   │                   ├── doc.go
│   │                   ├── fake
│   │                   │   ├── doc.go
│   │                   │   ├── fake_stable_client.go
│   │                   │   └── fake_student.go
│   │                   ├── generated_expansion.go
│   │                   ├── stable_client.go
│   │                   └── student.go
│   ├── informers
│   │   └── externalversions
│   │       ├── factory.go
│   │       ├── generic.go
│   │       ├── internalinterfaces
│   │       │   └── factory_interfaces.go
│   │       └── stable
│   │           ├── interface.go
│   │           └── v1
│   │               ├── interface.go
│   │               └── student.go
│   └── listers
│       └── stable
│           └── v1
│               ├── expansion_generated.go
│               └── student.go

4.编写controller的业务逻辑

参考sample-controller工程，写的比较简单

5.启动controller

[root@localhost samplecontroller]# ./samplecontroller
这是一个简易的自定制的k8s controller，用来演示k8s的终态运维的思想，
https://github.com/gfandada/samplecontroller，
gfandada@gmail.com
Usage:
  samplecontroller [command]
Available Commands:
  help        Help about any command
  run         run config=[kubeConfig的路径]
Flags:
      --config string   config file (default is $HOME/.samplecontroller.yaml)
  -h, --help            help for samplecontroller
  -t, --toggle          Help message for toggle
Use "samplecontroller [command] --help" for more information about a command.
[root@localhost samplecontroller]# ./samplecontroller run config=/root/.kube/config 
ERROR: logging before flag.Parse: I0415 15:02:28.619121  109337 samplecontroller.go:59] 创建事件广播器
ERROR: logging before flag.Parse: I0415 15:02:28.619246  109337 samplecontroller.go:76] 监听student的add/update/delete事件
ERROR: logging before flag.Parse: I0415 15:02:28.619264  109337 samplecontroller.go:102] 开始controller业务，开始一次缓存数据同步
ERROR: logging before flag.Parse: I0415 15:02:28.719511  109337 samplecontroller.go:107] 启动10个worker
ERROR: logging before flag.Parse: I0415 15:02:28.719547  109337 samplecontroller.go:112] worker已经全部启动
......
FIMXE ERROR: logging before flag.Parse多个flag库有些冲突，不影响本项目，正式开发可以考虑去掉cobra，打开flag.Parse()

6.修改crd实例文件观察controller

........
kubectl apply -f test1.yaml
kubectl describe std test1