spring-cloud-kubernetes是springcloud官方推出的开源项目，用于将spring cloud和spring boot应用运行在kubernetes环境，并且提供了通用的接口来调用kubernetes服务，github上官方地址是：https://github.com/spring-cloud/spring-cloud-kubernetes
本文是《spring-cloud-kubernetes实战系列》的第一篇，全文链接如下：
官方提供了简单的demo用于快速了解spring-cloud-kubernetes，但是成功运行此demo需要做一些设置和修改，这也是此文的意义所在，接下来我们一起实战这个demo；
本次实战的环境和版本信息如下：
上面提到的linux、minikube、java、maven，请确保已全部准备好，关于linux环境下minikube的安装和启动请参考《linux安装minikube指南 》。
官方demo包含在整个spring-cloud-kubernetes开源项目中，因此要下载整个开源项目，由于主干的提交一直很活跃，因此最好下载个release版本，我这里下载的是v1.0.1.release，如下图红框所示，地址是：https://github.com/spring-cloud/spring-cloud-kubernetes/releases
需要事先修改maven的设置，否则编译构建的时候会报错：
我要评论<plugingroups>
<plugingroup>io.fabric8</plugingroup>
<plugingroup>org.springframework.boot</plugingroup>
</plugingroups>
如果您想了解该错误的细节，请参考文章《使用fabric8-maven-plugin插件的错误处理(no plugin found for prefix 'fabric8')》；
[info] reactor summary for spring cloud kubernetes 1.0.1.release: [info] [info] spring cloud kubernetes :: dependencies ............ success [ 0.077 s] [info] spring cloud kubernetes ............................ success [ 2.575 s] [info] spring cloud kubernetes :: core .................... success [01:51 min] [info] spring cloud kubernetes :: config .................. success [ 21.357 s] [info] spring cloud kubernetes :: discovery ............... success [ 6.473 s] [info] spring cloud kubernetes :: ribbon .................. success [ 31.616 s] [info] spring cloud kubernetes :: starter ................. success [ 0.558 s] [info] spring cloud kubernetes :: starter :: config ....... success [ 0.569 s] [info] spring cloud kubernetes :: starter :: ribbon ....... success [ 0.595 s] [info] spring cloud kubernetes :: starter :: all .......... success [ 0.571 s] [info] spring cloud kubernetes :: examples ................ success [ 0.558 s] [info] spring cloud kubernetes :: examples :: reload configmap success [ 9.077 s] [info] spring cloud kubernetes :: examples :: hello world . success [ 1.323 s] [info] spring cloud kubernetes :: leader .................. success [ 7.395 s] [info] spring cloud kubernetes :: examples :: leader election success [ 0.594 s] [info] spring cloud kubernetes :: istio ................... success [ 12.788 s] [info] spring cloud kubernetes :: integration tests ....... success [ 0.574 s] [info] spring cloud kubernetes :: integration tests :: simple core success [02:14 min] [info] spring cloud kubernetes :: integration tests :: simple configmap success [ 0.646 s] [info] spring cloud kubernetes :: integration tests :: istio success [ 0.623 s] [info] spring cloud kubernetes :: integration tests :: discovery parent success [ 0.564 s] [info] spring cloud kubernetes :: integration tests :: discovery service a success [ 0.605 s] [info] spring cloud kubernetes :: integration tests :: discovery service b success [ 0.625 s] [info] spring cloud kubernetes :: integration tests :: discovery client success [ 0.608 s] [info] spring cloud kubernetes :: integration tests :: discovery tests success [ 1.440 s] [info] spring cloud kubernetes docs ....................... success [ 0.583 s] [info] ------------------------------------------------------------------------ [info] build success [info] ------------------------------------------------------------------------ [info] total time: 05:53 min [info] finished at: 2019-06-08t19:32:19+08:00 [info] ------------------------------------------------------------------------
mvn clean package fabric8:deploy -pkubernetes
构建和部署完成后，控制台输出以下信息：
... [info] installing /usr/local/work/demo/spring-cloud-kubernetes-1.0.1.release/spring-cloud-kubernetes-examples/kubernetes-hello-world-example/target/kubernetes-hello-world-1.0.1.release-sources.jar to /root/.m2/repository/org/springframework/cloud/kubernetes-hello-world/1.0.1.release/kubernetes-hello-world-1.0.1.release-sources.jar [info] [info] <<< fabric8-maven-plugin:3.5.37:deploy (default-cli) < install @ kubernetes-hello-world <<< [info] [info] [info] --- fabric8-maven-plugin:3.5.37:deploy (default-cli) @ kubernetes-hello-world --- [info] f8: using kubernetes at https://192.168.121.133:8443/ in namespace default with manifest /usr/local/work/demo/spring-cloud-kubernetes-1.0.1.release/spring-cloud-kubernetes-examples/kubernetes-hello-world-example/target/classes/meta-inf/fabric8/kubernetes.yml [info] using namespace: default [info] creating a service from kubernetes.yml namespace default name kubernetes-hello-world [info] created service: spring-cloud-kubernetes-examples/kubernetes-hello-world-example/target/fabric8/applyjson/default/service-kubernetes-hello-world.json [info] using namespace: default [info] creating a deployment from kubernetes.yml namespace default name kubernetes-hello-world [info] created deployment: spring-cloud-kubernetes-examples/kubernetes-hello-world-example/target/fabric8/applyjson/default/deployment-kubernetes-hello-world.json [info] f8: hint: use the command `kubectl get pods -w` to watch your pods start up [info] ------------------------------------------------------------------------ [info] build success [info] ------------------------------------------------------------------------ [info] total time: 16.047 s [info] finished at: 2019-06-08t19:50:50+08:00 [info] ------------------------------------------------------------------------
[root@minikube kubernetes-hello-world-example]# kubectl get services name type cluster-ip external-ip port(s) age kubernetes clusterip 10.96.0.1 <none> 443/tcp 10h kubernetes-hello-world nodeport 10.108.214.207 <none> 8080:30700/tcp 4m
[root@minikube kubernetes-hello-world-example]# kubectl get deployments name ready up-to-date available age kubernetes-hello-world 0/1 1 0 4m46s
[root@minikube kubernetes-hello-world-example]# kubectl get pods name ready status restarts age kubernetes-hello-world-7578f45c5d-hr4r7 0/1 running 1 6m
从上面的信息可以看出，部署虽然已经完成，但是pod是不可用的，访问网页试试，如下图，果然无法访问：
@restcontroller
public class hellocontroller {
private static final log log = logfactory.getlog(hellocontroller.class);
@autowired
private discoveryclient discoveryclient;
@requestmapping("/")
public string hello() {
return "hello world";
}
@requestmapping("/services")
public list<string> services() {
return this.discoveryclient.getservices();
}
}
现在真相大白了：部署到minikube上的pod，配置了探针地址是/health，但是服务中并没有此路径，因此探针检查一直无法通过；
搞清楚问题之后就可以动手解决问题了，这里有两种解决方式：
第一种，修改hellocontroller.java，增加一个方法，对应的地址是/health的服务；
第二种，修改deployment的配置，将探针地址改为现有的服务，例如"/"，这是个可用的服务；
第一种方法很简单，留给读者您来完成吧，我们来试试第二种：
kubectl edit deployment kubernetes-hello-world
[root@minikube examples]# kubectl get pods name ready status restarts age kubernetes-hello-world-6c5f75ff74-dnm2q 1/1 running 0 15s
访问地址http://192.168.121.133:30700 ，服务正常(192.168.121.133是宿主机ip地址)，如下图：
官方的demo无法在minikube上正常运行，还要我们自己去修改配置或者源码，官方的demo不应该会这样，在kubernetes-hello-world-example工程内的readme.md文档中发现了对此问题的说明，如下图红框所示，fabric8的maven插件在生成探针配置的是时候配错了url，因此官方建议我们去修改deployment的配置，将探针的地址从"/health"改为"/actuator/heath"，这个问题已经被提交到了fabric8社区，并且贴出了链接：
message: forbidden!configured service account doesn't have access. service account may have been revoked. services is forbidden: user "system:serviceaccount:default:default" cannot list resource "services" in api group "" in the namespace "default"
也就是说当前的system:serviceaccount账号是没有权限通过api server访问"services"资源的，此时最快的解决办法是提升账号权限：
kubectl create clusterrolebinding permissive-binding \ --clusterrole=cluster-admin \ --user=admin \ --user=kubelet \ --group=system:serviceaccounts
注意：以上办法只能用于开发和测试环境，不要用在生产环境，在生产环境应该参考kubernetes的rbac授权相关设置来处理。
如果您想尝试修改demo的源码并且部署上去，在编译阶段可能遇到以下问题：
[root@minikube kubernetes-hello-world-example]# mvn clean package fabric8:deploy -pkubernetes [info] scanning for projects... [info] [info] ----------< org.springframework.cloud:kubernetes-hello-world >---------- [info] building spring cloud kubernetes :: examples :: hello world 1.0.1.release [info] --------------------------------[ jar ]--------------------------------- [info] [info] --- maven-clean-plugin:2.5:clean (default-clean) @ kubernetes-hello-world --- [info] deleting /usr/local/work/demo/spring-cloud-kubernetes-1.0.1.release/spring-cloud-kubernetes-examples/kubernetes-hello-world-example/target [info] [info] --- maven-checkstyle-plugin:3.0.0:check (checkstyle-validation) @ kubernetes-hello-world --- [info] 开始检查…… [error] /usr/local/work/demo/spring-cloud-kubernetes-1.0.1.release/spring-cloud-kubernetes-examples/kubernetes-hello-world-example/src/main/java/org/springframework/cloud/kubernetes/examples/hellocontroller.java:33: 当前行匹配非法表达式： 'trailing whitespace'。 [regexp] 检查完成。 [info] ------------------------------------------------------------------------ [info] build failure [info] ------------------------------------------------------------------------ [info] total time: 2.976 s [info] finished at: 2019-06-08t22:15:37+08:00 [info] ------------------------------------------------------------------------ [error] failed to execute goal org.apache.maven.plugins:maven-checkstyle-plugin:3.0.0:check (checkstyle-validation) on project kubernetes-hello-world: failed during checkstyle execution: there is 1 error reported by checkstyle 8.12 with checkstyle.xml ruleset. -> [help 1] [error] [error] to see the full stack trace of the errors, re-run maven with the -e switch. [error] re-run maven using the -x switch to enable full debug logging. [error] [error] for more information about the errors and possible solutions, please read the following articles: [error] [help 1] http://cwiki.apache.org/confluence/display/maven/mojoexecutionexception
出现上述问题的原因是maven-checkstyle-plugin插件检查代码的style没有通过，我试过在mvn命令中添加skip参数，也试过在pom.xml中添加maven-checkstyle-plugin节点并且配置为skip，结果都没有用，最终用以下方法成功规避了此问题：
<properties>
<maven-checkstyle-plugin.failsonerror>false</maven-checkstyle-plugin.failsonerror>
<maven-checkstyle-plugin.failsonviolation>false</maven-checkstyle-plugin.failsonviolation>
<maven-checkstyle-plugin.includetestsourcedirectory>false</maven-checkstyle-plugin.includetestsourcedirectory></properties>
至此，官方demo的部署和运行都完成了，对spring-cloud-kubernetes算是有了初步认识，接下来的实战中，我们一起去深入的了解spring-cloud-kubernetes，看看kubernetes上的springcloud应用怎么开发；
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