etcd 是一个很好的例子，对于我们来说，我们只需要知道怎么把值放进去，然后怎么取出来，至于怎么认证，怎么升级，怎么管理，我们并不关心，所以，我们不关心的部分Operator帮我们管理
想要运行这个operator，首先我们要先创建一个CRD ，也就是说，Kuberntes 原生是不知道什么etcd的，也不知道该怎么帮你创建（原生支持的pod,例如你告诉kubernetes创建一个pod，它知道怎么创建，但是如果你如果什么都不做，直接让kubernetes创建一个etcd 资源，它就傻了），所以，我们首先要告诉Kubernetes 我们的etcd是怎么定义的
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cat etcd-operator-crd.yaml apiVersion: apiextensions.k8s.io/v1beta1 kind: CustomResourceDefinition metadata: name: etcdclusters.etcd.database.coreos.com spec: group: etcd.database.coreos.com names: kind: EtcdCluster listKind: EtcdClusterList plural: etcdclusters shortNames: - etcdclus - etcd singular: etcdcluster scope: Namespaced version: v1beta2 versions: - name: v1beta2 served: true storage: true kubectl create -f etcd-operator-crd.yaml customresourcedefinition.apiextensions.k8s.io/etcdclusters.etcd.database.coreos.com created kubectl get crd NAME CREATED AT etcdclusters.etcd.database.coreos.com 2020-07-18T13:45:18Z |
然后，我们还需要一个serviceaccount ， 因为我们要有权限能够运行一个etcd Operator（因为资源是新的，kubernetes也没有提前帮你分配相应的权限）
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cat etcd-operator-sa.yaml apiVersion: v1 kind: ServiceAccount metadata: name: etcd-operator-sa kubectl create -f etcd-operator-sa.yaml serviceaccount/etcd-operator-sa created |
接下来，我们就要分配给我们刚刚的serviceaacount分配权限，kubernetes的权限管理RBAC之前也整理过，
role 部分（定义了谁挂载了这个role就有权限对etcdclusters ,etcdbackups,etcdresores有*的权限，当然下边还额外给了Pod ，service等权限）
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cat etcd-operator-role.yaml apiVersion: rbac.authorization.k8s.io/v1 kind: Role metadata: name: etcd-operator-role rules: - apiGroups: - etcd.database.coreos.com resources: - etcdclusters - etcdbackups - etcdrestores verbs: - '*' - apiGroups: - "" resources: - pods - services - endpoints - persistentvolumeclaims - events verbs: - '*' - apiGroups: - apps resources: - deployments verbs: - '*' - apiGroups: - "" resources: - secrets verbs: - get |
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kubectl create -f etcd-operator-role.yaml role.rbac.authorization.k8s.io/etcd-operator-role created |
Role binding部分（这地方把我们的serviceaccount和role绑定了）
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cat etcd-operator-rolebinding.yaml apiVersion: rbac.authorization.k8s.io/v1 kind: RoleBinding metadata: name: etcd-operator-rolebinding roleRef: apiGroup: rbac.authorization.k8s.io kind: Role name: etcd-operator-role subjects: - kind: ServiceAccount name: etcd-operator-sa namespace: default |
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kubectl create -f etcd-operator-rolebinding.yaml rolebinding.rbac.authorization.k8s.io/etcd-operator-rolebinding created |
准备工作这里就结束了，这个时候,我们已经教会了Kubernetes 认识我们自定义的资源，这个时候我们就要把Operator启动起来，Operator就是一个pod， 这个pod会监听所有的资源创建，如果有人说自己要创建一个etcd，它就会和kubernetes说我来创建，这个pod里边写了如何备份，如何启动，如何调整集群相关的业务逻辑代码
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cat etcd-operator-deployment.yaml apiVersion: apps/v1 kind: Deployment metadata: name: etcd-operator spec: selector: matchLabels: app: etcd-operator replicas: 1 template: metadata: labels: app: etcd-operator spec: containers: - name: etcd-operator image: quay.io/coreos/etcd-operator:v0.9.4 command: - etcd-operator - --create-crd=false env: - name: MY_POD_NAMESPACE valueFrom: fieldRef: fieldPath: metadata.namespace - name: MY_POD_NAME valueFrom: fieldRef: fieldPath: metadata.name imagePullPolicy: IfNotPresent serviceAccountName: etcd-operator-sa |
这个就是operator pod的定义，所有核心的代码都在image 中，我们要做的就是，把这个pod 资源run起来
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$kubectl create -f etcd-operator-deployment.yaml deployment.apps/etcd-operator created $kubectl get deployments NAME READY UP-TO-DATE AVAILABLE AGE brazen-bee-mysql 1/1 1 1 219d etcd-operator 0/1 1 0 12s $kubectl get pods NAME READY STATUS RESTARTS AGE brazen-bee-mysql-7c5bb846c5-krbdf 1/1 Running 1 219d etcd-operator-6f6bbc45c-wc7tn 0/1 ContainerCreating 0 21s |
这个时候，所有的准备工作就完成了，这个时候我们就可以和创建deployment一样创建一个etcd cluster了
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$cat etcd-cluster-cr.yaml apiVersion: etcd.database.coreos.com/v1beta2 kind: EtcdCluster metadata: name: example-etcd-cluster spec: size: 3 version: 3.1.10 $kubectl create -f etcd-cluster-cr.yaml etcdcluster.etcd.database.coreos.com/example-etcd-cluster created |
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