3.15 Helm功能

比眉伴天荒 2022-12-22 09:06 98阅读 0赞

### 文章目录 ###

*  一、什么是Helm
 *  二、Helm的安装
 *  三、helm自定义模板
 *  四、helm基本操作

# 一、什么是Helm #

在未使用helm之前，k8s部署deployment、service等资源需要分别定义资源清单文件，每一个单独进行部署，尤其是微服务多应用后，步骤繁多，helm通过使用一键打包方式，支持版本已经发布部署以及管理，简化了k8s的应用部署和管理。  
helm是官方提供的类似于linux中yum包管理，对整个部署流程进行封装。helm包含两个重要概念：chart和release。chart即为把k8s部署步骤进行打包，release即为执行chart生成的版本。  
其实，helm可以类比docker，docker是把应用打包成镜像，helm是把k8s的部署步骤打包成chart；docker运行镜像创建容器，helm执行chart，生成release。  
Helm包含两个组件：Helm客户端和Tiller服务器  
Helm客户端负责chart和release的创建和管理以及与Tiller的交互；  
Tiller服务器运行在k8s的pod中，它会处理Helm客户端的请求，Tiller负责与API Server交互。

# 二、Helm的安装 #

**1、下载helm安装包以及准备工作**  
安装Helm的客户端，[下载][Link 1]helm安装包并解压赋可执行权限

tar -zxvf helm-v2.13.1-linux-amd64.tar.gz 	#解压helm安装包
    cp -a linux-amd64/helm /usr/local/bin/ 		#把解压包中的helm目录copy到/usr/local/bin/目录下
    chmod a+x /usr/local/bin/helm 				#为heml赋可执行权限

**2、为Tiller赋RBAC权限**  
Helm的服务端Tiller是运行在pod中的，那么该pod要与API Server通信的权限就需要API Server授权，而pod与API通信是采用的ServiceAccount机制，所以API需要通过RBAC为Tiller所在的pod中绑定的ServiceAccount授予访问权限。

下面创建名字为tiller的ServiceAccount，名称空间为kube-system，然后创建名为tiller的ClusterRoleBinding，通过ClusterRoleBindind把集群管理员角色cluster-admin绑定到了名为tiller的ServiceAccount中。

apiVersion: v1
    kind: ServiceAccount
    metadata:
      name: tiller
      namespace: kube-system
    ---
    apiVersion: rbac.authorization.k8s.io/v1beta1
    kind: ClusterRoleBinding
    metadata:
      name: tiller
    roleRef:
      apiGroup: rbac.authorization.k8s.io
      kind: ClusterRole
      name: cluster-admin   #cluster-admin是k8s中默认的管理员集群角色
    subjects:
    - kind: ServiceAccount
      name: tiller
      namespace: kube-system

kubectl apply -f teller-rbac-config.yaml

**3、安装tiller**  
安装Helm的服务器端Tiller，安装tiller，把tiller安装到pod中

helm init --service-account tiller --skip-refresh

执行上述命令后，tiller的pod已经创建完毕，在kube-system命名空间中，查看如下

[root@k8s-master01 teller]# kubectl get pod -n kube-system
    NAME                                   READY   STATUS    RESTARTS   AGE
    .......省略其它不相关pod
    tiller-deploy-58565b5464-6hdjz         0/1     ImagePullBackOff   0          1h

发现tiller的pod为启动成功，状态为ImagePullBackOff，说明镜像下载不成功，无法访问谷歌网站，下面通过导入镜像处理。

**4、下载Tiller镜像**  
[下载Tiller镜像][Tiller]到master节点的/root/work/image目录下，并分别把master主节点中的/root/work/image下的tiller镜像下发至k8s-node01和k8s-node02(本案例只有一个master和两个node节点)

scp helm-tiller.tar root@k8s-node01:/root/work/image
    scp helm-tiller.tar root@k8s-node02:/root/work/image

然后两个Node节点上分别执行docker导入tiller镜像

docker load -i helm-tiller.tar

执行上述命令后再次查询tiller的pod，发现已经运行成功

[root@k8s-master01 helm]# kubectl get pod -n kube-system
    NAME                                   READY   STATUS    RESTARTS   AGE
    .....省略不相关pod
    tiller-deploy-58565b5464-6hdjz         1/1     Running   0          23h

# 三、helm自定义模板 #

**1、自定义helm模板**  
创建nginx为例，以博主目录为例，首先在/root/work/helm/nginx目录下创建Chart.yaml模板文件：

name: nginx
    version: v0.3

然后在nginx目录下创建templates目录，在templates目录下放定义的k8s资源清单模板文件

#部署deployment的资源文件
    apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: mydeployment
      namespace: default
    spec:
      replicas: 3
      selector:
        matchLabels:
          app: myapp
          release: stabel
      template:
        metadata:
          labels:
            app: myapp
            release: stabel
        spec:
          containers:
          - name: myapp
            image: mynginx:v0.3
            imagePullPolicy: IfNotPresent
            ports:
            - name: http
              containerPort: 80

apiVersion: v1
    kind: Service
    metadata:
      name: myservice
      namespace: default
    spec:
      type: ClusterIP
      selector:
        app: myapp
        release: stabel
      ports:
      - name: http
        port: 8080
        targetPort: 80

然后使用helm命令执行上述定义的资源文件，创建当前目录下定义的deployment和service，在/root/work/helm/nginx目录下执行下述命令：

[root@k8s-master01 nginx]# helm install .
    NAME:   opulent-alligator
    LAST DEPLOYED: Sun Nov 22 10:49:15 2020
    NAMESPACE: default
    STATUS: DEPLOYED
    
    RESOURCES:
    ==> v1/Deployment
    NAME          READY  UP-TO-DATE  AVAILABLE  AGE
    mydeployment  0/3    0           0          0s
    
    ==> v1/Pod(related)
    NAME                           READY  STATUS             RESTARTS  AGE
    mydeployment-67667dddf9-5cfpf  0/1    ContainerCreating  0         0s
    mydeployment-67667dddf9-hbx2z  0/1    Pending            0         0s
    mydeployment-67667dddf9-lrz7j  0/1    Pending            0         0s
    
    ==> v1/Service
    NAME       TYPE       CLUSTER-IP     EXTERNAL-IP  PORT(S)   AGE
    myservice  ClusterIP  10.107.191.27  <none>       8080/TCP  0s

**2、在模板中使用配置文件**  
可以把配置资源清单中经常需要变动的一些变量放在配置文件中，随chart一起进行发布。  
例如经常需要改镜像和版本，首先在/root/work/helm/nginx目录下创建一个配置文件，比如values.yaml，在配置文件中进行修改变量，如下所示

image:
      respository: mynginx
      tag: v0.1

部署的deployment需要改成引用变量的形式，如下所示

apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: mydeployment
      namespace: default
    spec:
      replicas: 3
      selector:
        matchLabels:
          app: myapp
          release: stabel
      template:
        metadata:
          labels:
            app: myapp
            release: stabel
        spec:
          containers:
          - name: myapp
            image: { {  .Values.image.repository }}:{ {  .Values.image.tag }}
            imagePullPolicy: IfNotPresent
            ports:
            - name: http
              containerPort: 80

然后再更新修改后的chart

[root@k8s-master01 nginx]# helm upgrade opulent-alligator .
    Release "opulent-alligator" has been upgraded. Happy Helming!
    LAST DEPLOYED: Sun Nov 22 21:58:50 2020
    NAMESPACE: default
    STATUS: DEPLOYED
    
    RESOURCES:
    ==> v1/Deployment
    NAME          READY  UP-TO-DATE  AVAILABLE  AGE
    mydeployment  3/3    1           3          11h
    
    ==> v1/Pod(related)
    NAME                           READY  STATUS             RESTARTS  AGE
    mydeployment-59648694bf-v78fd  0/1    ContainerCreating  0         0s
    mydeployment-847f89d5cb-5s96g  1/1    Running            0         33m
    mydeployment-847f89d5cb-8bkqk  1/1    Running            0         33m
    mydeployment-847f89d5cb-bcxjv  1/1    Running            0         33m
    
    ==> v1/Service
    NAME       TYPE       CLUSTER-IP     EXTERNAL-IP  PORT(S)   AGE
    myservice  ClusterIP  10.107.191.27  <none>       8080/TCP  11h

除了上述方式在在values配置文件中指定变量的值，还可以在执行chart时，通过参数进行指定，例如

[root@k8s-master01 nginx]# helm upgrade opulent-alligator --set image.repository=mynginx --set image.tag=v0.2 .
    Release "opulent-alligator" has been upgraded. Happy Helming!
    LAST DEPLOYED: Sun Nov 22 22:05:35 2020
    NAMESPACE: default
    STATUS: DEPLOYED
    
    RESOURCES:
    ==> v1/Deployment
    NAME          READY  UP-TO-DATE  AVAILABLE  AGE
    mydeployment  3/3    0           3          11h
    
    ==> v1/Pod(related)
    NAME                           READY  STATUS   RESTARTS  AGE
    mydeployment-59648694bf-gqxcw  1/1    Running  0         6m43s
    mydeployment-59648694bf-v78fd  1/1    Running  0         6m45s
    mydeployment-59648694bf-wmrlz  1/1    Running  0         6m41s
    mydeployment-847f89d5cb-hgpvf  0/1    Pending  0         1s
    
    ==> v1/Service
    NAME       TYPE       CLUSTER-IP     EXTERNAL-IP  PORT(S)   AGE
    myservice  ClusterIP  10.107.191.27  <none>       8080/TCP  11h

# 四、helm基本操作 #

**1、列举已部署的release**

[root@k8s-master01 nginx]# helm ls
    NAME                    REVISION        UPDATED                         STATUS          CHART           APP VERSION     NAMESPACE
    opulent-alligator       1               Sun Nov 22 10:49:15 2020        DEPLOYED        nginx-v0.3                      default

**2、查询指定release的状态**

[root@k8s-master01 nginx]# helm status opulent-alligator
    LAST DEPLOYED: Sun Nov 22 10:49:15 2020
    NAMESPACE: default
    STATUS: DEPLOYED
    
    RESOURCES:
    ==> v1/Deployment
    NAME          READY  UP-TO-DATE  AVAILABLE  AGE
    mydeployment  3/3    3           3          10h
    
    ==> v1/Pod(related)
    NAME                           READY  STATUS   RESTARTS  AGE
    mydeployment-67667dddf9-5cfpf  1/1    Running  0         10h
    mydeployment-67667dddf9-hbx2z  1/1    Running  0         10h
    mydeployment-67667dddf9-lrz7j  1/1    Running  0         10h
    
    ==> v1/Service
    NAME       TYPE       CLUSTER-IP     EXTERNAL-IP  PORT(S)   AGE
    myservice  ClusterIP  10.107.191.27  <none>       8080/TCP  10h

**3、更新release**  
修改Chart后，需要更新，执行下述命令。比如镜像从mynginx:v0.3修改为mynginx:v0.2

[root@k8s-master01 nginx]# helm upgrade opulent-alligator .
    Release "opulent-alligator" has been upgraded. Happy Helming!
    LAST DEPLOYED: Sun Nov 22 21:25:09 2020
    NAMESPACE: default
    STATUS: DEPLOYED
    
    RESOURCES:
    ==> v1/Deployment
    NAME          READY  UP-TO-DATE  AVAILABLE  AGE
    mydeployment  3/3    1           3          10h
    
    ==> v1/Pod(related)
    NAME                           READY  STATUS             RESTARTS  AGE
    mydeployment-67667dddf9-5cfpf  1/1    Running            0         10h
    mydeployment-67667dddf9-hbx2z  1/1    Running            0         10h
    mydeployment-67667dddf9-lrz7j  1/1    Running            0         10h
    mydeployment-847f89d5cb-5s96g  0/1    ContainerCreating  0         1s
    
    ==> v1/Service
    NAME       TYPE       CLUSTER-IP     EXTERNAL-IP  PORT(S)   AGE
    myservice  ClusterIP  10.107.191.27  <none>       8080/TCP  10h

**4、查看release的历史**

[root@k8s-master01 nginx]# helm history opulent-alligator
    REVISION        UPDATED                         STATUS          CHART           DESCRIPTION     
    1               Sun Nov 22 10:49:15 2020        SUPERSEDED      nginx-v0.3      Install complete
    2               Sun Nov 22 21:25:09 2020        DEPLOYED        nginx-v0.3      Upgrade complete

**5、删除release**

[root@k8s-master01 nginx]# helm delete opulent-alligator
    release "opulent-alligator" deleted

注意如果已经删除创建的release，再创建相同名字的release就会报错，比如删除后再次执行`helm install --name opulent-alligator .`,会报错名字已经存在。因为已经删除的release还存在

[root@k8s-master01 nginx]# helm list --deleted
    NAME                    REVISION        UPDATED                         STATUS  CHART           APP VERSION     NAMESPACE
    opulent-alligator       4               Sun Nov 22 22:05:35 2020        DELETED nginx-v0.3                      default

**6、回退release**  
已经被删除的release，或者upgrrade后想回退到老版本，执行执行回退操作。例如回退上步骤删除的opulent-alligator，指定回退到3版本（第一次install，版本为1，以后每次upgrade都会增加一个版本号）

[root@k8s-master01 nginx]# helm rollback opulent-alligator 3
    Rollback was a success! Happy Helming!

**7、彻底删除release**  
第5步删除release后，通过–deleted还是可以查出被删除的release，然后回退被删除的release，但是如果确认确实不需要的release，可以进行彻底删除，彻底删除后的release不可再进行回滚。

[root@k8s-master01 nginx]# helm delete --purge opulent-alligator
    release "opulent-alligator" deleted

[Link 1]: https://github.com/helm/helm/releases
[Tiller]: https://mp.csdn.net/console/upDetailed