K8S/Kubernetes

helm介绍
helm是一个k8s的包管理工具，就像linux系统下的包管理器，如yum、apt等，可以很方便的将之前打包好的yaml文件部署到k8s上

相比之前的部署一个简单的服务流程：

(1)编写yaml文件

(2)创建pod

(3)创建svc

(4)做代理Ingress

这种部署单一的应用，相对于简单的应用比较合适，如果是微服务项目，需要几十个服务，每一个服务都有一套yaml文件，维护与更改就不是很方便 

但是使用helm可以：

(1)把yaml文件整体管理起来

(2)实现yaml的高效复用

(3)使用helm应用级别的版本管理(升级降级)

  其中有3个重要的概念

(1)helm：一个命令行客户端工具，主要是用于k8s应用chart的创建、打包、发布和管理

(2)chart：应用描述，一系列用于描述k8s资源相关文件的集合，把yaml打包，是yaml的集合，支持推送到docker仓库中

(3)release：基于chart的部署实体，应用级别的版本管理。一个chart被helm运行后将会生成对应的一个release，将在k8s中创建出真实运行的资源对象。

 helm v3版本安装

    (1)下载helm tar文件包，上传到linux服务器中

    (2)把helm文件移到/usr/bin目录下

    (3)完成

[root@k8s-master dwz]# tar -zxvf helm-v3.3.4-linux-amd64.tar.gz 
linux-amd64/
linux-amd64/README.md
linux-amd64/LICENSE
linux-amd64/helm
[root@k8s-master dwz]# ls
gisserver  helm-v3.3.4-linux-amd64.tar.gz  iserver  linux-amd64
[root@k8s-master dwz]# cd linux-amd64/
[root@k8s-master linux-amd64]# ls
helm  LICENSE  README.md
[root@k8s-master linux-amd64]# mv helm /usr/bin/
[root@k8s-master linux-amd64]# helm
The Kubernetes package manager

Common actions for Helm:

- helm search:    search for charts
- helm pull:      download a chart to your local directory to view
- helm install:   upload the chart to Kubernetes
- helm list:      list releases of charts

Environment variables:

| Name                               | Description                                                                       |
|------------------------------------|-----------------------------------------------------------------------------------|
| $HELM_CACHE_HOME                   | set an alternative location for storing cached files.                             |
| $HELM_CONFIG_HOME                  | set an alternative location for storing Helm configuration.                       |
| $HELM_DATA_HOME                    | set an alternative location for storing Helm data.                                |
| $HELM_DRIVER                       | set the backend storage driver. Values are: configmap, secret, memory, postgres   |
| $HELM_DRIVER_SQL_CONNECTION_STRING | set the connection string the SQL storage driver should use.                      |
| $HELM_NO_PLUGINS                   | disable plugins. Set HELM_NO_PLUGINS=1 to disable plugins.                        |
| $KUBECONFIG                        | set an alternative Kubernetes configuration file (default "~/.kube/config")       |

配置helm仓库

(1)添加仓库

helm repo add 仓库名称 仓库地址

[root@k8s-master linux-amd64]# helm repo add aliyun https://aliacs-app-catalog.oss-cn-hangzhou.aliyuncs.com/charts-incubator/ 
"aliyun" has been added to your repositories

(2)查看仓库

[root@k8s-master linux-amd64]# helm repo list
NAME      URL                                                                      
aliyun    https://aliacs-app-catalog.oss-cn-hangzhou.aliyuncs.com/charts-incubator/

(3)更新仓库地址

[root@k8s-master ~]# helm repo update
Hang tight while we grab the latest from your chart repositories...
...Successfully got an update from the "aliyun" chart repository
Update Complete. ⎈Happy Helming!⎈

(4)移除仓库

[root@k8s-master ~]# helm  repo remove aliyun
"aliyun" has been removed from your repositories
[root@k8s-master ~]# helm repo list
Error: no repositories to show

使用helm快速部署应用实例

添加微软仓库

[root@k8s-master ~]# helm repo add weiruan http://mirror.azure.cn/kubernetes/charts/
"weiruan" has been added to your repositories

(1)使用命令搜索应用(weave)

[root@k8s-master ~]# helm search repo weave
NAME                   CHART VERSION    APP VERSION    DESCRIPTION                                       
weiruan/weave-cloud    0.3.9            1.4.0          DEPRECATED - Weave Cloud is a add-on to Kuberne...
weiruan/weave-scope    1.1.12           1.12.0         DEPRECATED - A Helm chart for the Weave Scope c...

(2)根据搜索内容选择安装应用

[root@k8s-master ~]# helm install ui weiruan/weave-scope

(3)查看安装列表

[root@k8s-master ~]# helm list
NAME    NAMESPACE    REVISION    UPDATED                                    STATUS      CHART                APP VERSION
ui      default      1           2020-10-28 15:19:15.421361319 +0800 CST    deployed    weave-scope-1.1.8    1.12.0     

(4)查看安装具体信息

[root@k8s-master ~]# helm status ui
NAME: ui
LAST DEPLOYED: Wed Oct 28 15:19:15 2020
NAMESPACE: default
STATUS: deployed
REVISION: 1
NOTES:
You should now be able to access the Scope frontend in your web browser, by
using kubectl port-forward:

kubectl -n default port-forward $(kubectl -n default get endpoints \
ui-weave-scope -o jsonpath='{.subsets[0].addresses[0].targetRef.name}') 8080:4040

then browsing to http://localhost:8080/.
For more details on using Weave Scope, see the Weave Scope documentation:

https://www.weave.works/docs/scope/latest/introducing/

(5)查看pod运行状态

[root@k8s-master ~]# kubectl get pod 
NAME                                            READY   STATUS        RESTARTS   AGE
weave-scope-agent-ui-655pp                      1/1     Running       3          15d
weave-scope-agent-ui-bzttt                      1/1     Running       2          15d
weave-scope-agent-ui-hkxfz                      1/1     Running       1          15d
weave-scope-cluster-agent-ui-5d4d6c97bf-5xpqf   1/1     Terminating   0          8d
weave-scope-cluster-agent-ui-5d4d6c97bf-f528k   1/1     Running       1          7d1h
weave-scope-frontend-ui-757c6668c5-vqpdj        1/1     Running       1          7d1h
weave-scope-frontend-ui-757c6668c5-zhlzp        1/1     Terminating   0          8d

(6)查看svc情况

[root@k8s-master ~]# kubectl get svc
NAME             TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
kubernetes       ClusterIP   10.96.0.1       <none>        443/TCP        50d
ui-weave-scope   ClusterIP   10.102.105.28   <none>        80:32448/TCP   15d

现在的weave的svc类型是ClusterIP，需要给改成NodePort类型，外部就可以访问了

[root@k8s-master ~]# kubectl edit svc ui-weave-scope

保存退出

再查看svc

[root@k8s-master ~]# kubectl get svc
NAME             TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
kubernetes       ClusterIP   10.96.0.1       <none>        443/TCP        50d
ui-weave-scope   NodePort    10.102.105.28   <none>        80:32448/TCP   15d

使用浏览器访问http://ip:32448

完成一键安装部署

创建自定义Chart

1.使用命令创建Chart

[root@k8s-master helm]# helm create mychart
Creating mychart

创建成功之后，会生成四个文件

charts 

Chart.yaml     当前chart属性配置信息

templates      编写yaml文件存放的目录

values.yaml    yaml文件可以使用的全局变量

2.在templates中创建yaml文件

[root@k8s-master templates]# kubectl create deployment web --image=nginx --dry-run -o yaml > deployment-nginx.yaml

[root@k8s-master templates]# kubectl get pod 
NAME                                            READY   STATUS        RESTARTS   AGE
weave-scope-agent-ui-655pp                      1/1     Running       3          15d
weave-scope-agent-ui-bzttt                      1/1     Running       2          15d
weave-scope-agent-ui-hkxfz                      1/1     Running       1          15d
weave-scope-cluster-agent-ui-5d4d6c97bf-5xpqf   1/1     Terminating   0          8d
weave-scope-cluster-agent-ui-5d4d6c97bf-f528k   1/1     Running       1          7d4h
weave-scope-frontend-ui-757c6668c5-vqpdj        1/1     Running       1          7d4h
weave-scope-frontend-ui-757c6668c5-zhlzp        1/1     Terminating   0          8d
web-d86c95cc9-kvssx                             1/1     Running       0          30m

删除web这个pod，因为我们要用helm方式创建

[root@k8s-master templates]# kubectl delete deployment web
deployment.apps "web" deleted

kubectl expose  deployment web --port=80 --target-port=80 --type=NodePort --dry-run -o yaml > service .yaml

创建完deployment之后，pod成功启动才能创建svc，要不然会报错(这两步是为了生成yaml文件，自己写有些麻烦)

[root@k8s-master templates]# ls
deployment-nginx.yaml  service.yaml

3.安装mychart

[root@k8s-master helm]# helm install nginx mychart/
NAME: nginx
LAST DEPLOYED: Thu Nov 12 20:18:36 2020
NAMESPACE: default
STATUS: deployed
REVISION: 1
TEST SUITE: None

查看pod、svc

[root@k8s-master helm]# kubectl get pod 
NAME                                            READY   STATUS        RESTARTS   AGE
weave-scope-agent-ui-655pp                      1/1     Running       3          15d
weave-scope-agent-ui-bzttt                      1/1     Running       2          15d
weave-scope-agent-ui-hkxfz                      1/1     Running       1          15d
weave-scope-cluster-agent-ui-5d4d6c97bf-5xpqf   1/1     Terminating   0          8d
weave-scope-cluster-agent-ui-5d4d6c97bf-f528k   1/1     Running       1          7d4h
weave-scope-frontend-ui-757c6668c5-vqpdj        1/1     Running       1          7d4h
weave-scope-frontend-ui-757c6668c5-zhlzp        1/1     Terminating   0          8d
web-d86c95cc9-vzmnd                             1/1     Running       0          6m23s
[root@k8s-master helm]# kubectl get svc
NAME             TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
kubernetes       ClusterIP   10.96.0.1       <none>        443/TCP        50d
ui-weave-scope   NodePort    10.102.105.28   <none>        80:32448/TCP   15d
web              NodePort    10.98.105.180   <none>        80:31375/TCP   6m28s

浏览器访问：http://ip:31375

重载应用

[root@k8s-master helm]# helm upgrade nginx mychart
Release "nginx" has been upgraded. Happy Helming!
NAME: nginx
LAST DEPLOYED: Thu Nov 12 21:49:50 2020
NAMESPACE: default
STATUS: deployed
REVISION: 3
TEST SUITE: None