spring-cloud-kubernetes官方demo运行实战
关于spring-cloud-kubernetes
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
系列文章列表
本文是《spring-cloud-kubernetes实战系列》的第一篇,全文链接如下:
官方demo
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;
环境信息
本次实战的环境和版本信息如下:
- 操作系统:centos linux release 7.6.1810
- minikube:1.1.1
- java:1.8.0_191
- maven:3.6.0
- fabric8-maven-plugin插件:3.5.37
- spring-cloud-kubernetes:1.0.1.release
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 》。
下载源码
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
修改maven设置
需要事先修改maven的设置,否则编译构建的时候会报错:
- 打开maven的配置文件settings.xml,完整路径是apache-maven-3.6.0/conf/settings.xm;
- 在settings.xml文件内,找到plugingroups节点,在里面增加两行,修改完成后效果如下:
<plugingroups> <plugingroup>io.fabric8</plugingroup> <plugingroup>org.springframework.boot</plugingroup> </plugingroups>
- 修改完毕保存退出,maven设置完成;
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')》;
编译项目源码
- 将上图中的源码下载解压,得到一个新的文件夹spring-cloud-kubernetes-1.0.1.release;
- 进入文件夹spring-cloud-kubernetes-1.0.1.release,执行命令mvn clean compile -u,完全编译整个工程,由于要下载大量依赖库所以较为耗时,我这里是二十分钟以上(这一步不是必须的,看个人爱好吧),构建通过后如下所示:
[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] ------------------------------------------------------------------------
- 进入目录spring-cloud-kubernetes-1.0.1.release/spring-cloud-kubernetes-examples/kubernetes-hello-world-example,这里面就是官方的入门demo,执行以下命令开始构建并且会部署到minikube:
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] ------------------------------------------------------------------------
- 查看服务,已经创建了,类型是nodeport ,并且将8080端口映射到宿主机的30700端口,说明可以用http://宿主机ip:30700来访问此服务:
[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
- 查看部署,发现始终未能进入ready状态:
[root@minikube kubernetes-hello-world-example]# kubectl get deployments name ready up-to-date available age kubernetes-hello-world 0/1 1 0 4m46s
- 查看pod,发现新建的pod始终未能进入ready状态:
[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:
检查问题
- 执行命令kubectl describe pod kubernetes-hello-world-7578f45c5d-hr4r7检查pod的具体情况,如下图红框所示,两个探针检查都失败了:
- 再看看控制台输出的pod基本情况,里面有探针的信息,如下图所示,两个探针的地址都是/health:
- 打开demo的源码,如下所示,根本就没有路径为/health的服务:
@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;
解决问题
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:
- 执行以下命令,开始编辑deployment:
kubectl edit deployment kubernetes-hello-world
- 在编辑页面上找到两个探针的配置,都从"/health"改成"/",如下图两个红框所示:
- 修改完毕后,像普通vim操作一样"wq"保存退出,配置会立即生效,稍等一会儿再看pod情况,发现pod的name已经变了,并且状态已经成为ready,证明旧的pod已经销毁,新的pod被创建并且探针测试通过:
[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:
官方解释
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:
权限问题
刚才我们看过了hellocontroller.java的源码,里面还有个路径为"/services"的接口,在minikube环境下访问此接口可以成功返回,内容是当前minikube环境的服务信息,但是如果部署在正式的kubernetes环境,访问此接口会返回以下错误:
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。
修改源码时遇到的错误怎么规避
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:
- 打开pom.xml文件;
- 找到节点properties(如果没有就创建),增加以下三个属性配置,这样配置的作用是在style检查失败、校验失败、单元测试代码检查失败这三种情况下,都不会导致整个maven构建的失败:
<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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