kubebuilder实战之二：初次体验kubebuilder

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本篇概览

本文是《kubebuilder实战》系列的第二篇，前文将kubebuilder环境准备完毕，今天咱们在此环境创建CRD和Controller，再部署到kubernetes环境并且验证是否生效，整篇文章由以下内容组成：

创建API(CRD和Controller)
构建和部署CRD
编译和运行controller
创建CRD对应的实例
删除实例并停止controller
将controller制作成docker镜像
卸载和清理

创建helloworld项目

执行以下命令，创建helloworld项目：

mkdir -p $GOPATH/src/helloworld
cd $GOPATH/src/helloworld
kubebuilder init --domain com.bolingcavalry

控制台输出类似以下内容：

[root@kubebuilder helloworld]# kubebuilder init --domain com.bolingcavalry
Writing scaffold for you to edit...
Get controller runtime:
$ go get sigs.k8s.io/[email protected]
Update go.mod:
$ go mod tidy
Running make:
$ make
/root/gopath/bin/controller-gen object:headerFile="hack/boilerplate.go.txt" paths="./..."
go fmt ./...
go vet ./...
go build -o bin/manager main.go
Next: define a resource with:
$ kubebuilder create api

等待数分钟后创建完成，在$GOPATH/src/helloworld目录下新增以下内容，可见这是个标准的go module工程：

[root@kubebuilder ~]# tree $GOPATH/src/helloworld
/root/gopath/src/helloworld
├── bin
│   └── manager
├── config
│   ├── certmanager
│   │   ├── certificate.yaml
│   │   ├── kustomization.yaml
│   │   └── kustomizeconfig.yaml
│   ├── default
│   │   ├── kustomization.yaml
│   │   ├── manager_auth_proxy_patch.yaml
│   │   ├── manager_webhook_patch.yaml
│   │   └── webhookcainjection_patch.yaml
│   ├── manager
│   │   ├── kustomization.yaml
│   │   └── manager.yaml
│   ├── prometheus
│   │   ├── kustomization.yaml
│   │   └── monitor.yaml
│   ├── rbac
│   │   ├── auth_proxy_client_clusterrole.yaml
│   │   ├── auth_proxy_role_binding.yaml
│   │   ├── auth_proxy_role.yaml
│   │   ├── auth_proxy_service.yaml
│   │   ├── kustomization.yaml
│   │   ├── leader_election_role_binding.yaml
│   │   ├── leader_election_role.yaml
│   │   └── role_binding.yaml
│   └── webhook
│       ├── kustomization.yaml
│       ├── kustomizeconfig.yaml
│       └── service.yaml
├── Dockerfile
├── go.mod
├── go.sum
├── hack
│   └── boilerplate.go.txt
├── main.go
├── Makefile
└── PROJECT

9 directories, 30 files

创建API(CRD和Controller)

接下来要要创建资源相关的内容了，group/version/kind这三部分可以确定资源的唯一身份，命令如下：

cd $GOPATH/src/helloworld
kubebuilder create api \
--group webapp \
--version v1 \
--kind Guestbook

控制台会提醒是否创建资源(Create Resource [y/n])，输入y
接下来控制台会提醒是否创建控制器(Create Controller [y/n])，输入y
kubebuilder会根据上述命令新增多个文件，如下图红框所示：

构建和部署CRD

kubebuilder提供的Makefile将构建和部署工作大幅度简化，执行以下命令会将最新构建的CRD部署在kubernetes上：

cd $GOPATH/src/helloworld
make install

控制台输出如下内容，提示部署成功：

[root@kubebuilder helloworld]# make install
/root/gopath/bin/controller-gen "crd:trivialVersions=true" rbac:roleName=manager-role webhook paths="./..." output:crd:artifacts:config=config/crd/bases
kustomize build config/crd | kubectl apply -f -
Warning: apiextensions.k8s.io/v1beta1 CustomResourceDefinition is deprecated in v1.16+, unavailable in v1.22+; use apiextensions.k8s.io/v1 CustomResourceDefinition
customresourcedefinition.apiextensions.k8s.io/guestbooks.webapp.com.bolingcavalry created

编译和运行controller

kubebuilder自动生成的controller源码地址是：$GOPATH/src/helloworld/controllers/guestbook_controller.go ，内容如下：

package controllers

import (
    "context"

    "github.com/go-logr/logr"
    "k8s.io/apimachinery/pkg/runtime"
    ctrl "sigs.k8s.io/controller-runtime"
    "sigs.k8s.io/controller-runtime/pkg/client"

    webappv1 "helloworld/api/v1"
)

// GuestbookReconciler reconciles a Guestbook object
type GuestbookReconciler struct {
    client.Client
    Log    logr.Logger
    Scheme *runtime.Scheme
}

// +kubebuilder:rbac:groups=webapp.com.bolingcavalry,resources=guestbooks,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=webapp.com.bolingcavalry,resources=guestbooks/status,verbs=get;update;patch

func (r *GuestbookReconciler) Reconcile(req ctrl.Request) (ctrl.Result, error) {
    _ = context.Background()
    _ = r.Log.WithValues("guestbook", req.NamespacedName)

    // your logic here

    return ctrl.Result{}, nil
}

func (r *GuestbookReconciler) SetupWithManager(mgr ctrl.Manager) error {
    return ctrl.NewControllerManagedBy(mgr).
        For(&webappv1.Guestbook{}).
        Complete(r)
}

本文以体验基本流程为主，不深入研究源码，所以对上面的代码仅做少量修改，用于验证是否能生效，改动如下图红框所示：

执行以下命令，会编译并启动刚才修改的controller：

cd $GOPATH/src/helloworld
make run

此时控制台输出以下内容，这里要注意，controller是在kubebuilder电脑上运行的，一旦使用Ctrl+c中断控制台，就会导致controller停止：

[root@kubebuilder helloworld]# make run
/root/gopath/bin/controller-gen object:headerFile="hack/boilerplate.go.txt" paths="./..."
go fmt ./...
go vet ./...
/root/gopath/bin/controller-gen "crd:trivialVersions=true" rbac:roleName=manager-role webhook paths="./..." output:crd:artifacts:config=config/crd/bases
go run ./main.go
2021-01-23T20:58:35.107+0800    INFO    controller-runtime.metrics    metrics server is starting to listen    {"addr": ":8080"}
2021-01-23T20:58:35.108+0800    INFO    setup    starting manager
2021-01-23T20:58:35.108+0800    INFO    controller-runtime.manager    starting metrics server    {"path": "/metrics"}
2021-01-23T20:58:35.108+0800    INFO    controller-runtime.controller    Starting EventSource    {"controller": "guestbook", "source": "kind source: /, Kind="}
2021-01-23T20:58:35.208+0800    INFO    controller-runtime.controller    Starting Controller    {"controller": "guestbook"}
2021-01-23T20:58:35.209+0800    INFO    controller-runtime.controller    Starting workers    {"controller": "guestbook", "worker count": 1}

创建Guestbook资源的实例

现在kubernetes已经部署了Guestbook类型的CRD，而且对应的controller也已正在运行中，可以尝试创建Guestbook类型的实例了(相当于有了pod的定义后，才可以创建pod)；
kubebuilder已经自动创建了一个类型的部署文件：$GOPATH/src/helloworld/config/samples/webapp_v1_guestbook.yaml ，内容如下，很简单，接下来咱们就用这个文件来创建Guestbook实例：

apiVersion: webapp.com.bolingcavalry/v1
kind: Guestbook
metadata:
  name: guestbook-sample
spec:
  # Add fields here
  foo: bar

重新打开一个控制台，登录kubebuilder电脑，执行以下命令即可创建Guestbook类型的实例：

cd $GOPATH/src/helloworld
kubectl apply -f config/samples/

如下所示，控制台提示资源创建成功：

[root@kubebuilder helloworld]# kubectl apply -f config/samples/
guestbook.webapp.com.bolingcavalry/guestbook-sample created

用kubectl get命令可以看到实例已经创建：

[root@kubebuilder helloworld]# kubectl get Guestbook
NAME               AGE
guestbook-sample   112s

用命令kubectl edit Guestbook guestbook-sample编辑该实例，修改的内容如下图红框所示：

此时去controller所在控制台，可以看到新增和修改的操作都有日志输出，咱们新增的日志都在里面，代码调用栈一目了然：

2021-01-24T09:51:50.418+0800    INFO    controllers.Guestbook    1. default/guestbook-sample
2021-01-24T09:51:50.418+0800    INFO    controllers.Guestbook    2. goroutine 188 [running]:
runtime/debug.Stack(0xc0002a1808, 0xc0002fc600, 0x1b)
    /root/go/src/runtime/debug/stack.go:24 +0x9f
helloworld/controllers.(*GuestbookReconciler).Reconcile(0xc0003c9dd0, 0xc0002d02f9, 0x7, 0xc0002d02e0, 0x10, 0x12f449647b, 0xc000456f30, 0xc000456ea8, 0xc000456ea0)
    /root/gopath/src/helloworld/controllers/guestbook_controller.go:49 +0x1a9
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).reconcileHandler(0xc00022a480, 0x1430e00, 0xc0003e7560, 0x0)
    /root/gopath/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:256 +0x166
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).processNextWorkItem(0xc00022a480, 0xc000469600)
    /root/gopath/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:232 +0xb0
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).worker(0xc00022a480)
    /root/gopath/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:211 +0x2b
k8s.io/apimachinery/pkg/util/wait.JitterUntil.func1(0xc000292980)
    /root/gopath/pkg/mod/k8s.io/[email protected]/pkg/util/wait/wait.go:152 +0x5f
k8s.io/apimachinery/pkg/util/wait.JitterUntil(0xc000292980, 0x3b9aca00, 0x0, 0x1609101, 0xc000102480)
    /root/gopath/pkg/mod/k8s.io/[email protected]/pkg/util/wait/wait.go:153 +0x105
k8s.io/apimachinery/pkg/util/wait.Until(0xc000292980, 0x3b9aca00, 0xc000102480)
    /root/gopath/pkg/mod/k8s.io/[email protected]/pkg/util/wait/wait.go:88 +0x4d
created by sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func1
    /root/gopath/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:193 +0x32d

2021-01-24T09:51:50.418+0800    DEBUG    controller-runtime.controller    Successfully Reconciled    {"controller": "guestbook", "request": "default/guestbook-sample"}


2021-01-24T09:52:33.632+0800    INFO    controllers.Guestbook    1. default/guestbook-sample
2021-01-24T09:52:33.633+0800    INFO    controllers.Guestbook    2. goroutine 188 [running]:
runtime/debug.Stack(0xc0002a1808, 0xc0003fa5e0, 0x1b)
    /root/go/src/runtime/debug/stack.go:24 +0x9f
helloworld/controllers.(*GuestbookReconciler).Reconcile(0xc0003c9dd0, 0xc0002d02f9, 0x7, 0xc0002d02e0, 0x10, 0x1d0410fe42, 0xc000456f30, 0xc000456ea8, 0xc000456ea0)
    /root/gopath/src/helloworld/controllers/guestbook_controller.go:49 +0x1a9
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).reconcileHandler(0xc00022a480, 0x1430e00, 0xc0003d24c0, 0x0)
    /root/gopath/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:256 +0x166
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).processNextWorkItem(0xc00022a480, 0xc000469600)
    /root/gopath/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:232 +0xb0
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).worker(0xc00022a480)
    /root/gopath/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:211 +0x2b
k8s.io/apimachinery/pkg/util/wait.JitterUntil.func1(0xc000292980)
    /root/gopath/pkg/mod/k8s.io/[email protected]/pkg/util/wait/wait.go:152 +0x5f
k8s.io/apimachinery/pkg/util/wait.JitterUntil(0xc000292980, 0x3b9aca00, 0x0, 0x1609101, 0xc000102480)
    /root/gopath/pkg/mod/k8s.io/[email protected]/pkg/util/wait/wait.go:153 +0x105
k8s.io/apimachinery/pkg/util/wait.Until(0xc000292980, 0x3b9aca00, 0xc000102480)
    /root/gopath/pkg/mod/k8s.io/[email protected]/pkg/util/wait/wait.go:88 +0x4d
created by sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func1
    /root/gopath/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:193 +0x32d

2021-01-24T09:52:33.633+0800    DEBUG    controller-runtime.controller    Successfully Reconciled    {"controller": "guestbook", "request": "default/guestbook-sample"}

删除实例并停止controller

不再需要Guestbook实例的时候，执行以下命令即可删除：

cd $GOPATH/src/helloworld
kubectl delete -f config/samples/

不再需要controller的时候，去它的控制台使用Ctrl+c中断即可；

将controller制作成docker镜像

至此，咱们已经体验过了kubebuilder的基本功能，不过实际生产环境中controller一般都会运行在kubernetes环境内，像上面这种运行在kubernetes之外的方式就不合适了，咱们来试试将其做成docker镜像然后在kubernetes环境运行；
这里有个要求，就是您要有个kubernetes可以访问的镜像仓库，例如局域网内的Harbor，或者公共的hub.docker.com，我这为了操作方便选择了hub.docker.com，使用它的前提是拥有hub.docker.com的注册帐号；
在kubebuilder电脑上，打开一个控制台，执行docker login命令登录，根据提示输入hub.docker.com的帐号和密码，这样就可以在当前控制台上执行docker push命令将镜像推送到hub.docker.com上了（这个网站的网络很差，可能要登录好几次才能成功）；
执行以下命令构建docker镜像并推送到hub.docker.com，镜像名为bolingcavalry/guestbook:002：

cd $GOPATH/src/helloworld
make docker-build docker-push IMG=bolingcavalry/guestbook:002

hub.docker.com的网络状况不是一般的差，kubebuilder电脑上的docker一定要设置镜像加速，上述命令如果遭遇超时失败，请重试几次，此外，构建过程中还会下载诸多go模块的依赖，也需要您耐心等待，也很容易遇到网络问题，需要多次重试，所以，最好是使用局域网内搭建的Habor服务；
最终，命令执行成功后输出如下：

[root@kubebuilder helloworld]# make docker-build docker-push IMG=bolingcavalry/guestbook:002
/root/gopath/bin/controller-gen object:headerFile="hack/boilerplate.go.txt" paths="./..."
go fmt ./...
go vet ./...
/root/gopath/bin/controller-gen "crd:trivialVersions=true" rbac:roleName=manager-role webhook paths="./..." output:crd:artifacts:config=config/crd/bases
go test ./... -coverprofile cover.out
?       helloworld    [no test files]
?       helloworld/api/v1    [no test files]
ok      helloworld/controllers    8.604s    coverage: 0.0% of statements
docker build . -t bolingcavalry/guestbook:002
Sending build context to Docker daemon  40.27MB
Step 1/14 : FROM golang:1.13 as builder
 ---> d6f3656320fe
Step 2/14 : WORKDIR /workspace
 ---> Using cache
 ---> 83d05ead1041
Step 3/14 : COPY go.mod go.mod
 ---> Using cache
 ---> ae3e15a529f4
Step 4/14 : COPY go.sum go.sum
 ---> Using cache
 ---> 082223532ccc
Step 5/14 : RUN go mod download
 ---> Using cache
 ---> bcdcfa1d65ca
Step 6/14 : COPY main.go main.go
 ---> Using cache
 ---> 81d6a629ca98
Step 7/14 : COPY api/ api/
 ---> Using cache
 ---> 75f99b174e97
Step 8/14 : COPY controllers/ controllers/
 ---> b130d9f47903
Step 9/14 : RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 GO111MODULE=on go build -a -o manager main.go
 ---> Running in 768880aca19f
Removing intermediate container 768880aca19f
 ---> bb4a494d3b43
Step 10/14 : FROM gcr.io/distroless/static:nonroot
 ---> 947e6f3ed7c1
Step 11/14 : WORKDIR /
 ---> Using cache
 ---> 22cc43cef8fb
Step 12/14 : COPY --from=builder /workspace/manager .
 ---> 2137778f22c0
Step 13/14 : USER nonroot:nonroot
 ---> Running in 18295673073d
Removing intermediate container 18295673073d
 ---> f7545379ab1f
Step 14/14 : ENTRYPOINT ["/manager"]
 ---> Running in 550c47dd61dc
Removing intermediate container 550c47dd61dc
 ---> 31cb31a6b03f
Successfully built 31cb31a6b03f
Successfully tagged bolingcavalry/guestbook:002
docker push bolingcavalry/guestbook:002
The push refers to repository [docker.io/bolingcavalry/guestbook]
99035107a955: Pushed 
728501c5607d: Layer already exists 
002: digest: sha256:54f8ec88511cce5b04c5d65cc15e0f7a7b4a8afb6b235904a638bff79e3c5784 size: 739

去hub.docker.com网站看看，如下图，新镜像已经上传，这样只要任何机器只要能上网就能pull此镜像到本地使用了：

镜像准备好之后，执行以下命令即可在kubernetes环境部署controller：

cd $GOPATH/src/helloworld
make deploy IMG=bolingcavalry/guestbook:002

控制台会提示各类资源被创建（rbac居多）：

[root@kubebuilder ~]# cd $GOPATH/src/helloworld
[root@kubebuilder helloworld]# make deploy IMG=bolingcavalry/guestbook:002
/root/gopath/bin/controller-gen "crd:trivialVersions=true" rbac:roleName=manager-role webhook paths="./..." output:crd:artifacts:config=config/crd/bases
cd config/manager && kustomize edit set image controller=bolingcavalry/guestbook:002
kustomize build config/default | kubectl apply -f -
namespace/helloworld-system created
Warning: apiextensions.k8s.io/v1beta1 CustomResourceDefinition is deprecated in v1.16+, unavailable in v1.22+; use apiextensions.k8s.io/v1 CustomResourceDefinition
customresourcedefinition.apiextensions.k8s.io/guestbooks.webapp.com.bolingcavalry configured
role.rbac.authorization.k8s.io/helloworld-leader-election-role created
clusterrole.rbac.authorization.k8s.io/helloworld-manager-role created
clusterrole.rbac.authorization.k8s.io/helloworld-proxy-role created
Warning: rbac.authorization.k8s.io/v1beta1 ClusterRole is deprecated in v1.17+, unavailable in v1.22+; use rbac.authorization.k8s.io/v1 ClusterRole
clusterrole.rbac.authorization.k8s.io/helloworld-metrics-reader created
rolebinding.rbac.authorization.k8s.io/helloworld-leader-election-rolebinding created
clusterrolebinding.rbac.authorization.k8s.io/helloworld-manager-rolebinding created
clusterrolebinding.rbac.authorization.k8s.io/helloworld-proxy-rolebinding created
service/helloworld-controller-manager-metrics-service created
deployment.apps/helloworld-controller-manager created

此时去看kubernetes环境的pod，发现确实已经新增了controller，如下图红框：

11.细心的您应该会发现上图黄框中显示这个pod实际上有两个容器，用kubectl describe命令细看，分别是kube-rbac-proxy和manager，如下图：

由于有两个容器，那么查看日志时就要指定其中一个了，咱们的controller对应的是manager容器，因此查看日志的命令是：

kubectl logs -f \
helloworld-controller-manager-689d4b6f5b-h9pzg \
-n helloworld-system \
-c manager

再次创建Guestbook资源的实例，依旧是kubectl apply -f config/samples/命令，再去看manager容器的日志，可见咱们修改的内容已经打印出来了：

卸载和清理

体验完毕后，如果想把前面创建的资源和CRD全部清理掉，可以执行以下命令：

cd $GOPATH/src/helloworld
make uninstall

至此，通过kubebuilder创建Operator相关资源的基本流程，咱们已经体验过一遍了，本篇以熟悉工具和流程为主，并未体验到Operator实质性的强大功能，这些都留待后面的章节吧，咱们逐步深入学习实践；

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