Helm：Kubernetes的包管理器：7:Helm 3的使用示例
这篇文章以Helm 3和相应的Kubernetes集群环境安装设定之后，以用Helm 3安装和删除一个MySQL的实例（Release）来说明Helm 3的常用命令和特点。
环境准备
- Helm 3环境
[root@liumiaocn ~]# cat /etc/redhat-release
CentOS Linux release 7.6.1810 (Core)
[root@liumiaocn ~]# uname -a
Linux liumiaocn 3.10.0-957.el7.x86_64 #1 SMP Thu Nov 8 23:39:32 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
[root@liumiaocn ~]#
[root@liumiaocn ~]# helm version
version.BuildInfo{Version:"v3.0.0", GitCommit:"e29ce2a54e96cd02ccfce88bee4f58bb6e2a28b6", GitTreeState:"clean", GoVersion:"go1.13.4"}
[root@liumiaocn ~]#
- kubernetes环境
[root@liumiaocn ~]# kubectl version
Client Version: version.Info{Major:"1", Minor:"16", GitVersion:"v1.16.3-k3s.2", GitCommit:"e7e6a3c4e9a7d80b87793612730d10a863a25980", GitTreeState:"clean", BuildDate:"2019-11-18T18:31:23Z", GoVersion:"go1.13.4", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"16", GitVersion:"v1.16.3-k3s.2", GitCommit:"e7e6a3c4e9a7d80b87793612730d10a863a25980", GitTreeState:"clean", BuildDate:"2019-11-18T18:31:23Z", GoVersion:"go1.13.4", Compiler:"gc", Platform:"linux/amd64"}
[root@liumiaocn ~]#
安装方式可参看：https://liumiaocn.blog.csdn.net/article/details/103360312
常用命令一览
| 命令 | Helm 2 | Helm 3 | 命令使用频度 | 命令说明 |
|---|---|---|---|---|
| fetch | 有 | 无 | 高 | 从仓库下载Chart并解压到本地目录 |
| init | 有 | 无 | 中 | 初始化Helm客户端和服务器端设定 |
| install | 有 | 有 | 高 | 安装Chart |
| list | 有 | 有 | 高 | 显示Release列表信息 |
| repo | 有 | 有 | 高 | 对Char仓库进行添加、显示、删除、更新和索引生成的操作 |
| search | 有 | 有 | 高 | 按输入的关键字进行Chart的搜索和显示 |
| version | 有 | 有 | 中 | 显示客户端/服务器端版本信息 |
Helm 3常见操作
操作1: 初始化
执行命令：helm repo add stable https://kubernetes-charts.storage.googleapis.com
Helm 3由于移除了Tiller，所以只需要添加repo即可。执行日志示例如下所示：
[root@liumiaocn ~]# helm repo add stable https://kubernetes-charts.storage.googleapis.com
"stable" has been added to your repositories
[root@liumiaocn ~]# helm repo list
NAME URL
stable https://kubernetes-charts.storage.googleapis.com
[root@liumiaocn ~]#
操作2: 搜索和确认Chart信息
Helm通过Chart来提供包的安装，可以通过search和inspect命令来确认可用的Chart的信息。但是需要注意的是Helm 3的search命令稍微发生了点变化
[root@liumiaocn ~]# helm search repo stable/mysql
NAME CHART VERSION APP VERSION DESCRIPTION
stable/mysql 1.4.0 5.7.27 Fast, reliable, scalable, and easy to use open-...
stable/mysqldump 2.6.0 2.4.1 A Helm chart to help backup MySQL databases usi...
[root@liumiaocn ~]#
由于Helm 3 中已经删除了helm inspect命令 ，可以使用helm show chart stable/mysql来先确认整体信息
[root@liumiaocn ~]# helm show chart stable/mysql
apiVersion: v1
appVersion: 5.7.27
description: Fast, reliable, scalable, and easy to use open-source relational database
system.
home: https://www.mysql.com/
icon: https://www.mysql.com/common/logos/logo-mysql-170x115.png
keywords:
- mysql
- database
- sql
maintainers:
- email: [email protected]
name: olemarkus
- email: [email protected]
name: viglesiasce
name: mysql
sources:
- https://github.com/kubernetes/charts
- https://github.com/docker-library/mysql
version: 1.4.0
[root@liumiaocn ~]#
然后使用helm show values stable/mysql继续确认此Chart的详细信息
[root@liumiaocn ~]# helm show values stable/mysql
## mysql image version
## ref: https://hub.docker.com/r/library/mysql/tags/
##
image: "mysql"
imageTag: "5.7.14"
busybox:
image: "busybox"
tag: "1.29.3"
testFramework:
enabled: true
image: "dduportal/bats"
tag: "0.4.0"
## Specify password for root user
##
## Default: random 10 character string
# mysqlRootPassword: testing
## Create a database user
##
# mysqlUser:
## Default: random 10 character string
# mysqlPassword:
## Allow unauthenticated access, uncomment to enable
##
# mysqlAllowEmptyPassword: true
## Create a database
##
# mysqlDatabase:
## Specify an imagePullPolicy (Required)
## It's recommended to change this to 'Always' if the image tag is 'latest'
## ref: http://kubernetes.io/docs/user-guide/images/#updating-images
##
imagePullPolicy: IfNotPresent
## Additionnal arguments that are passed to the MySQL container.
## For example use --default-authentication-plugin=mysql_native_password if older clients need to
## connect to a MySQL 8 instance.
args: []
extraVolumes: |
# - name: extras
# emptyDir: {}
extraVolumeMounts: |
# - name: extras
# mountPath: /usr/share/extras
# readOnly: true
extraInitContainers: |
# - name: do-something
# image: busybox
# command: ['do', 'something']
# Optionally specify an array of imagePullSecrets.
# Secrets must be manually created in the namespace.
# ref: https://kubernetes.io/docs/concepts/containers/images/#specifying-imagepullsecrets-on-a-pod
# imagePullSecrets:
# - name: myRegistryKeySecretName
## Node selector
## ref: https://kubernetes.io/docs/concepts/configuration/assign-pod-node/#nodeselector
nodeSelector: {}
## Tolerations for pod assignment
## Ref: https://kubernetes.io/docs/concepts/configuration/taint-and-toleration/
##
tolerations: []
livenessProbe:
initialDelaySeconds: 30
periodSeconds: 10
timeoutSeconds: 5
successThreshold: 1
failureThreshold: 3
readinessProbe:
initialDelaySeconds: 5
periodSeconds: 10
timeoutSeconds: 1
successThreshold: 1
failureThreshold: 3
## Persist data to a persistent volume
persistence:
enabled: true
## database data Persistent Volume Storage Class
## If defined, storageClassName: 操作3: 安装MySQL并确认结果
使用helm install进行MySQL的安装，并使用helm ls确认安装后的结果。但是helm install也发生了小小的变动，就是必须要指定名称
[root@liumiaocn ~]# export KUBECONFIG=/etc/rancher/k3s/k3s.yaml
[root@liumiaocn ~]# helm install excited-squid stable/mysql
NAME: excited-squid
LAST DEPLOYED: Wed Dec 4 05:29:35 2019
NAMESPACE: default
STATUS: deployed
REVISION: 1
NOTES:
MySQL can be accessed via port 3306 on the following DNS name from within your cluster:
excited-squid-mysql.default.svc.cluster.local
To get your root password run:
MYSQL_ROOT_PASSWORD=$(kubectl get secret --namespace default excited-squid-mysql -o jsonpath="{.data.mysql-root-password}" | base64 --decode; echo)
To connect to your database:
1. Run an Ubuntu pod that you can use as a client:
kubectl run -i --tty ubuntu --image=ubuntu:16.04 --restart=Never -- bash -il
2. Install the mysql client:
$ apt-get update && apt-get install mysql-client -y
3. Connect using the mysql cli, then provide your password:
$ mysql -h excited-squid-mysql -p
To connect to your database directly from outside the K8s cluster:
MYSQL_HOST=127.0.0.1
MYSQL_PORT=3306
# Execute the following command to route the connection:
kubectl port-forward svc/excited-squid-mysql 3306
mysql -h ${MYSQL_HOST} -P${MYSQL_PORT} -u root -p${MYSQL_ROOT_PASSWORD}
[root@liumiaocn ~]#
安装之后即可使用helm ls确认创建的Release了
[root@liumiaocn ~]# helm ls
NAME NAMESPACE REVISION UPDATED STATUS CHART APP VERSION
excited-squid default 1 2019-12-04 05:29:35.201587574 -0500 EST deployed mysql-1.4.0 5.7.27
[root@liumiaocn ~]#
同时也可确认pod也确实已经处于Running的状态了
[root@liumiaocn ~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
excited-squid-mysql-649c99cbcf-2n6xs 1/1 Running 0 18m
[root@liumiaocn ~]#
这样就成功的将MySQL使用Helm 3的方式进行了安装。