Metacontroller介绍及使用
简介
Metacontroller是GKE为k8s开发的一个附加组件，用简单的脚本便可以方便的管理自定义控制器。
概念
- CRD 自定义资源
- Metacontroller Metacontroller控制器本身
- DecoratorController Metacontroller中用于向现有资源添加新行为
- CompositeController Metacontroller中用于通过父对象管理子对象
安装
# 创建命名空间
kubectl create namespace metacontroller
# 创建serviceaccount和rolebiding
kubectl apply -f https://raw.githubusercontent.com/GoogleCloudPlatform/metacontroller/master/manifests/metacontroller-rbac.yaml
# 创建metacontroller crd 和 metacontroller statefulset
kubectl apply -f https://raw.githubusercontent.com/GoogleCloudPlatform/metacontroller/master/manifests/metacontroller.yaml
创建一个控制器
目标
通过HelloWorld自定义资源来创建pod，打印hello
创建HelloWorld CRD
cat << EOF | kubectl apply -f -
apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
name: helloworlds.example.com
spec:
group: example.com
version: v1
names:
kind: HelloWorld
plural: helloworlds
singular: helloworld
scope: Namespaced
EOF
创建CompositeController
cat << EOF | kubectl apply -f -
apiVersion: metacontroller.k8s.io/v1alpha1
kind: CompositeController
metadata:
name: hello-controller
spec:
# 生成标签，模拟内置job，防止夸资源共享pod
generateSelector: true
# watch的父资源
parentResource:
apiVersion: example.com/v1
resource: helloworlds
# 生成的子资源
childResources:
- apiVersion: v1
resource: pods
updateStrategy:
method: Recreate
# 钩子
hooks:
sync:
webhook:
url: http://hello-controller.hello/sync
EOF
实现自己的webhook
webhook流程
创建crd resource –>metacontroller收到变化通知—>发送crd和期望pod数量到webhook —> webhook解析crd返回pod列表,及请求状态（pod数量）—>metacontroller判断状态正常—>创建pod
webhook示例：
from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer
import json
class Controller(BaseHTTPRequestHandler):
def sync(self, parent, children):
# Compute status based on observed state.
desired_status = {
"pods": len(children["Pod.v1"])
}
# Generate the desired child object(s).
who = parent.get("spec", {}).get("who", "World")
desired_pods = [
{
"apiVersion": "v1",
"kind": "Pod",
"metadata": {
"name": parent["metadata"]["name"]
},
"spec": {
"restartPolicy": "OnFailure",
"containers": [
{
"name": "hello",
"image": "busybox",
"command": ["echo", "Hello, %s!" % who]
}
]
}
}
]
return {"status": desired_status, "children": desired_pods}
def do_POST(self):
# Serve the sync() function as a JSON webhook.
observed = json.loads(self.rfile.read(int(self.headers.getheader("content-length"))))
desired = self.sync(observed["parent"], observed["children"])
self.send_response(200)
self.send_header("Content-type", "application/json")
self.end_headers()
self.wfile.write(json.dumps(desired))
HTTPServer(("", 80), Controller).serve_forever()本文参与 腾讯云自媒体分享计划，分享自微信公众号。
原始发表：2019-06-28，如有侵权请联系 cloudcommunity@tencent.com 删除
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