K8s Aggregation API体验

环境

OS: CentOS 7.5
Kubernetes v1.11.6
Etcd 3.3.10
Docker 1.13.1

什么是Aggregation API

Aggregation API和crd都可以在不修改k8s核心代码前提下，并扩展k8s api，是一种实现方式.

什么时候考虑用Aggregation API

考虑使用Aggregation API	考虑使用stand-alone API
Your API is Declarative.	Your API does not fit the Declarative model.
You want your new types to be readable and writable using kubectl.	kubectl support is not required
You want to view your new types in a Kubernetes UI, such as dashboard, alongside built-in types.	Kubernetes UI support is not required.
You are developing a new API.	You already have a program that serves your API and works well.
You are willing to accept the format restriction that Kubernetes puts on REST resource paths, such as API Groups and Namespaces. (See the API Overview.)	You need to have specific REST paths to be compatible with an already defined REST API.
Your resources are naturally scoped to a cluster or to namespaces of a cluster.	Cluster or namespace scoped resources are a poor fit; you need control over the specifics of resource paths.
You want to reuse Kubernetes API support features.	You don’t need those features.

CRD和Aggregation API差异对比

易用程度、高级功能及灵活性、公共点：

见https://kubernetes.io/docs/concepts/extend-kubernetes/api-extension/custom-resources/

demo操作

kube-apiserver增加如下配置：

--requestheader-client-ca-file=/etc/kubernetes/ssl/ca.pem
--proxy-client-cert-file=/etc/kubernetes/ssl/admin.pem
--proxy-client-key-file=/etc/kubernetes/ssl/admin-key.pem

如果kube-proxy没在master上运行，增加如下配置

--enable-aggregator-routing=true

用sample-apiserver这个项目来体验Aggregation API，此外apiserver-builder也可以生成Aggregation API的框架

mkdir -p $GOPATH/src/k8s.io/
cd $GOPATH/src/k8s.io/

克隆项目

git clone https://github.com/kubernetes/sample-apiserver.git
cd sample-apiserver
go mod vendor

编译

CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -a -o artifacts/simple-image/kube-sample-apiserver

编译镜像

docker build -t kube-sample-apiserver ./artifacts/simple-image

In-cluster部署

kubectl apply -f artifacts/example

查看Aggregation API是否生效

kubectl get apiservices.apiregistration.k8s.io

验证

kubectl apply -f  artifacts/flunders/01-flunder.yaml
kubectl get flunders.wardle.k8s.io

参考链接

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