Helm：Kubernetes的包管理器：4:初始化操作 (Helm 2 vs Helm 3)

这篇文章搭建一下Helm 2和Helm 3使用的集群环境，并在其中分别安装Helm 2和Helm 3，然后通过比较Helm 2和Helm 3下初始化操作的方式，从而更好的了解其不同之处。

前提准备

Helm 3

• Helm 3环境

[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 ~]# cat /etc/redhat-release 
CentOS Linux release 7.6.1810 (Core) 
[root@liumiaocn ~]# 
[root@liumiaocn ~]# helm version
version.BuildInfo{Version:"v3.0.0", GitCommit:"e29ce2a54e96cd02ccfce88bee4f58bb6e2a28b6", GitTreeState:"clean", GoVersion:"go1.13.4"}
[root@liumiaocn ~]# 

安装方法可参看：https://liumiaocn.blog.csdn.net/article/details/103360312

• 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 ~]#

Helm 2

• Helm 2环境

liumiao $ cat /etc/os-release
NAME="Ubuntu"
VERSION="16.04.2 LTS (Xenial Xerus)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 16.04.2 LTS"
VERSION_ID="16.04"
HOME_URL="http://www.ubuntu.com/"
SUPPORT_URL="http://help.ubuntu.com/"
BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/"
VERSION_CODENAME=xenial
UBUNTU_CODENAME=xenial
liumiao $ helm version
Client: &version.Version{SemVer:"v2.8.2", GitCommit:"a80231648a1473929271764b920a8e346f6de844", GitTreeState:"clean"}
Server: &version.Version{SemVer:"v2.8.2", GitCommit:"a80231648a1473929271764b920a8e346f6de844", GitTreeState:"clean"}
liumiao $

• kubernetes环境

liumiao $ kubectl version
Client Version: version.Info{Major:"1", Minor:"14", GitVersion:"v1.14.0", GitCommit:"641856db18352033a0d96dbc99153fa3b27298e5", GitTreeState:"clean", BuildDate:"2019-03-25T15:53:57Z", GoVersion:"go1.12.1", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"14", GitVersion:"v1.14.0", GitCommit:"641856db18352033a0d96dbc99153fa3b27298e5", GitTreeState:"clean", BuildDate:"2019-03-25T15:45:25Z", GoVersion:"go1.12.1", Compiler:"gc", Platform:"linux/amd64"}
liumiao $

Helm 2 vs Helm 3

Helm 2和Helm 3最大的区别是什么？Tiller，首先来看一下Helm 2的基本构成：

在Helm 2的时代，Helm是由两个东西构成：

• Helm Client：Helm客户端
• Tiller Server： Helm服务器端
  Helm 2是一个典型的C/S的架构，Tiller服务器端需要安装在Kubernetes集群之中。一般来说在Helm 2的时候，需要做很多额外的设定，比如创建一个SA（service acount），赋予其RBAC的权限，然后才能使用。整体使用方式如下图所示：
  
  从中可以看到TILLER在HELM和Kubernetes集群之间起到一个中转的作用。而相较于Helm 2, Helm 3就更为简单了，移除了Tiller Server，只剩下一个Helm Client，在使用中就是一个二进制可执行文件，也无需在像Helm 3中部署Tiller Server，也迎合了社区很多使用者的期待。而Helm 3如何与Kubernetes集群进行沟通的呢，很简单，与当前用户进行绑定，使用当前用户的kubeconfig。

二进制包的区别

在早期的Helm 2版本中，是有helm和tiller两个二进制文件的，而Helm 3只有一个。虽然在诸如Helm 2.8.2的版本中只有一个二进制文件，Helm 2中还是存在初始化操作的这条命令的，使用helm init命令时还是能够非常清楚地看到tiller的存在的。

初始化操作

• Helm 2: helm init
  缺省方式下在Helm 2环境下执行helm init，执行示例日志如下所示：

liumiao $ ls
liumiao $ pwd
/root/helm2test
liumiao $ ls
liumiao $ helm init
Creating /root/.helm
Creating /root/.helm/repository
Creating /root/.helm/repository/cache
Creating /root/.helm/repository/local
Creating /root/.helm/plugins
Creating /root/.helm/starters
Creating /root/.helm/cache/archive
Creating /root/.helm/repository/repositories.yaml
Adding stable repo with URL: https://kubernetes-charts.storage.googleapis.com
Adding local repo with URL: http://127.0.0.1:8879/charts
$HELM_HOME has been configured at /root/.helm.

Tiller (the Helm server-side component) has been installed into your Kubernetes Cluster.

Please note: by default, Tiller is deployed with an insecure 'allow unauthenticated users' policy.
For more information on securing your installation see: https://docs.helm.sh/using_helm/#securing-your-helm-installation
Happy Helming!
liumiao $ ls
liumiao $ ls /root/.helm/
cache  plugins  repository  starters
liumiao $

实际上初始化最重要的内容之一就是设定repository，在helm init的命令之中我们也可以看到添加repository的日志信息。使用helm repo list命令来进行确认

liumiao $ helm repo list
NAME    URL
stable  https://kubernetes-charts.storage.googleapis.com
local   http://127.0.0.1:8879/charts
liumiao $

另外Helm 2在helm init之后一般会使用helm repo update命令，这样像helm version等命令才能更好地运行。接下来就可以使用helm search命令搜索mysql相关的chart了。

liumiao $ helm search 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...
stable/prometheus-mysql-exporter        0.5.2           v0.11.0         A Helm chart for prometheus mysql exporter with...
stable/percona                          1.2.0           5.7.17          free, fully compatible,enhanced, open source d...
stable/percona-xtradb-cluster           1.0.3           5.7.19          free, fully compatible,enhanced, open source d...
stable/phpmyadmin                       4.2.4           4.9.2           phpMyAdmin is an mysql administration frontend
stable/gcloud-sqlproxy                  0.6.1           1.11            DEPRECATED Google CloudSQL Proxy
stable/mariadb                          7.2.1           10.3.20         Fast, reliable, scalable, and easy to use open-...
liumiao $

• Helm 3: 初期化操作
  Helm 3中没有了helm init这条命令，但是增加了一条helm env命令，可以看到缺省的设置已经有了一些。

[root@liumiaocn ~]# helm env
HELM_PLUGINS="/root/.local/share/helm/plugins"
HELM_REGISTRY_CONFIG="/root/.config/helm/registry.json"
HELM_REPOSITORY_CACHE="/root/.cache/helm/repository"
HELM_REPOSITORY_CONFIG="/root/.config/helm/repositories.yaml"
HELM_NAMESPACE="default"
HELM_KUBECONTEXT=""
HELM_BIN="helm"
HELM_DEBUG="false"
[root@liumiaocn ~]# 

确认一下当前的repository，提示了一个错误信息，实际上是因为还没有设定。

[root@liumiaocn ~]# helm repo list
Error: no repositories to show
[root@liumiaocn ~]# echo $?
1
[root@liumiaocn ~]# 

而在Helm 2中如果不使用helm init命令直接进行helm repo list的情况下，同样会提示出错信息，示例信息如下所示：

Error: Couldn't load repositories file (/root/.helm/repository/repositories.yaml).
You might need to run `helm init` (or `helm init --client-only` if tiller is already installed)

通过helm repo add命令我们添加https://kubernetes-charts.storage.googleapis.com作为repository。

[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 ~]# 

在Helm 3中增强了search的功能，作为代价，直接使用helm search mysql无法进行搜索了，需要指定repo，执行示例日志如下所示：

[root@liumiaocn ~]# helm search repo 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...
stable/prometheus-mysql-exporter	0.5.2        	v0.11.0    	A Helm chart for prometheus mysql exporter with...
stable/percona                  	1.2.0        	5.7.17     	free, fully compatible, enhanced, open source d...
stable/percona-xtradb-cluster   	1.0.3        	5.7.19     	free, fully compatible, enhanced, open source d...
stable/phpmyadmin               	4.2.4        	4.9.2      	phpMyAdmin is an mysql administration frontend    
stable/gcloud-sqlproxy          	0.6.1        	1.11       	DEPRECATED Google Cloud SQL Proxy                 
stable/mariadb                  	7.2.1        	10.3.20    	Fast, reliable, scalable, and easy to use open-...
[root@liumiaocn ~]#