SpringCloud实战之Kubernetes项目运行示例
全文速览：
文章背景：
2019年开始 SpringCloud 开始向 K8S容器化流程演变，逐步诞生了【Spring-Cloud-Kubernetes】
环境要求：
- maven 3.+
- jdk17
获取源码并加载环境
从github仓库获取源码
git clone https://github.com/spring-cloud/spring-cloud-kubernetes.git
导入IDEA后，确认以下构建环境
- maven 3.+
- jdk17
- 当前springcloudkubernetes版本：3.1.0-SNAPSHOT
- spring-cloud-build 4.1.0-SNAPSHOT
由于代码涉及snapshot库的代码拉取（体现Spring全家桶的协同），需要关注项目根目录下的.setting文件，作为一般本地maven文件的补充，主要关注仓库部分，构建的时候可以直接选定这个setting文件，消除全项目红波浪线的问题。
确认以上环境后
./mvnw clean package -Dmaven.test.skip=true
保持网络通畅，期间会需要连接docker，现在打包工具，确定JRE版本，下载JRE版本，打包到镜像仓库等动作。
spring-cloud-kubernetes下的示例
使用spring-cloud-kubernetes下的example体验springcloud与kubernetes的融合与互动
/spring-cloud-kubernetes/spring-cloud-kubernetes-examples/kubernetes-leader-election-example
mvn spring-boot:build-image -Dspring-boot.build-image.imageName=org/kubernetes-leader-election-example
:~$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
busybox latest a416a98b71e2 4 weeks ago 4.26MB
registry.cn-hangzhou.aliyuncs.com/google_containers/kube-apiserver v1.24.1 e9f4b425f919 15 months ago 130MB
registry.cn-hangzhou.aliyuncs.com/google_containers/kube-scheduler v1.24.1 18688a72645c 15 months ago 51MB
registry.cn-hangzhou.aliyuncs.com/google_containers/kube-proxy v1.24.1 beb86f5d8e6c 15 months ago 110MB
registry.cn-hangzhou.aliyuncs.com/google_containers/kube-controller-manager v1.24.1 b4ea7e648530 15 months ago 119MB
registry.cn-hangzhou.aliyuncs.com/google_containers/etcd 3.5.3-0 aebe758cef4c 16 months ago 299MB
registry.cn-hangzhou.aliyuncs.com/google_containers/pause 3.7 221177c6082a 17 months ago 711kB
registry.cn-hangzhou.aliyuncs.com/google_containers/coredns v1.8.6 a4ca41631cc7 22 months ago 46.8MB
k8s.gcr.io/pause 3.6 6270bb605e12 24 months ago 683kB
registry.cn-hangzhou.aliyuncs.com/google_containers/storage-provisioner v5 6e38f40d628d 2 years ago 31.5MB
org/kubernetes-leader-election-example
eval $(minikube docker-env)
Mac minikube 本地构建执行 SpringCloud-Kubernetes-Example
Mac 安装 minikube 此处不描述。
本文主要参照官方流程，依据源码构建实践示例代码。
依赖版本说明：
docker 20.10.20minikube v1.28.0k8s 1.24.1maven 3.6jdk17spring-cloud-kubernetes 3.1.0-SNAPSHOTspring-cloud-build 4.1.0-SNAPSHOT
以上maven和jdk是必要条件，注意版本的对应
基础条件准备
- 安装
maven3+环境 - 安装
JDK17环境 - 启动
docker - 启动
minikubeminikube start
查看 minikube 访问的 docker 环境
minikube docker-env
:~$ minikube docker-env
export DOCKER_TLS_VERIFY="1"
export DOCKER_HOST="tcp://127.0.0.1:54965"
export DOCKER_CERT_PATH="~/.minikube/certs"
export MINIKUBE_ACTIVE_DOCKERD="minikube"
# To point your shell to minikube's docker-daemon, run:
# eval $(minikube -p minikube docker-env)
如果本地docker没有habor等私仓环境,注意这行注释，需要让当前shell去访问minikube的docker 需要执行 eval $(minikube -p minikube docker-env)。官方文档也很细心地写明了这个指令哦，对于小白还是比较友好
指令执行后，即可在当前这个shell直接docker images看到仓库中的镜像了
以下开始执行示例项目的部署
进入example项目文件夹下，为项目创建role和role-binding
kubectl apply -f leader-role.yml
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
name: leader
labels:
app: kubernetes-leader-election-example
group: org.springframework.cloud
rules:
- apiGroups:
- ""
resources:
- pods
verbs:
- watch
- get
- apiGroups:
- ""
resources:
- configmaps
verbs:
- watch
- get
- update
# resourceNames:
# - <config-map name>
----
kubectl apply -f leader-rolebinding.yml
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
labels:
app: kubernetes-leader-election-example
group: org.springframework.cloud
name: leader
roleRef:
apiGroup: ""
kind: Role
name: leader
subjects:
- kind: ServiceAccount
name: default
apiGroup: ""
在example目录下通过maven组件构建docker镜像
./mvnw spring-boot:build-image -Dspring-boot.build-image.imageName=org/kubernetes-leader-election-example
通过以下yaml构建服务
---
apiVersion: v1
kind: List
items:
- apiVersion: v1
kind: Service
metadata:
labels:
app: kubernetes-leader-election-example
name: kubernetes-leader-election-example
spec:
ports:
- name: http
port: 80
targetPort: 8080
selector:
app: kubernetes-leader-election-example
type: ClusterIP
- apiVersion: v1
kind: ServiceAccount
metadata:
labels:
app: kubernetes-leader-election-example
name: kubernetes-leader-election-example
- apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
labels:
app: kubernetes-leader-election-example
name: kubernetes-leader-election-example:view
roleRef:
kind: Role
apiGroup: rbac.authorization.k8s.io
name: namespace-reader
subjects:
- kind: ServiceAccount
name: kubernetes-leader-election-example
- apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
namespace: default
name: namespace-reader
rules:
- apiGroups: ["", "extensions", "apps"]
resources: ["configmaps", "pods", "services", "endpoints", "secrets"]
verbs: ["get", "list", "watch"]
- apiVersion: apps/v1
kind: Deployment
metadata:
name: kubernetes-leader-election-example
spec:
selector:
matchLabels:
app: kubernetes-leader-election-example
template:
metadata:
labels:
app: kubernetes-leader-election-example
spec:
serviceAccountName: kubernetes-leader-election-example
containers:
- name: kubernetes-leader-election-example
image: org/kubernetes-leader-election-example:latest
imagePullPolicy: IfNotPresent
readinessProbe:
httpGet:
port: 8080
path: /actuator/health/readiness
livenessProbe:
httpGet:
port: 8080
path: /actuator/health/liveness
ports:
- containerPort: 8080
将内部服务的8080映射到ClusterIP的80上，获取本机的代理地址，端口未指定所以每次启动是随机的
:~$ minikube service kubernetes-leader-election-example --url
😿 service default/kubernetes-leader-election-example has no node port
http://127.0.0.1:57562
❗ Because you are using a Docker driver on darwin, the terminal needs to be open to run it.
访问地址 http://127.0.0.1:57562 就能获取响应，由于只有一个节点，所以这个节点就是主节点
curl http://127.0.0.1:57562
I am 'kubernetes-leader-election-example-5fbf89948f-gf8gd' and I am the leader of the 'world'
增加实例数增加到2个
kubectl scale --replicas=2 deployment.apps/kubernetes-leader-election-example
NAMESPACE NAME READY STATUS RESTARTS AGE
default kubernetes-leader-election-example-5fbf89948f-427xs 1/1 Running 4 (25m ago) 3d21h
default kubernetes-leader-election-example-5fbf89948f-gf8gd 1/1 Running 4 (25m ago) 3d21h
由于节点数增加，两个服务也就开始存在负载均衡的效果，依赖k8s调度，此时请求目标地址 http://127.0.0.1:57562, 请求一般都是落在从节点上，反复请求节点会交替但都是到从节点
I am 'kubernetes-leader-election-example-5fbf89948f-427xs' but I am not a leader of the 'world'
I am 'kubernetes-leader-election-example-5fbf89948f-gf8gd' but I am not a leader of the 'world'
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