关于helm

helm是针对k8s的应用管理工具，可以和管理rpm包的yum进行类比，只不过helm的管理对象为chart，也就是一组定义了k8s相关资源的yaml文件。通过 Helm 可以打包应用、管理应用依赖关系、管理应用版本并发布应用到软件仓库。

安装helm

helm也是C/S架构的服务，helm是一个命令行下的客户端工具，而服务端是Tiller。

1、安装helm客户端命令行

因此我们先安装helm客户端，通过helm github，我们选择一个版本下载二进制安装包，

wget https://get.helm.sh/helm-v2.14.1-linux-amd64.tar.gz
tar -xf helm-v2.14.1-linux-amd64.tar.gz

解压后我们可以看到helm的二进制文件，

[root@CentOS-7-4 /home/k8s/linux-amd64]# ls
.  ..  helm  LICENSE  README.md  tiller

将二进制文件helm拷贝到环境变量PATH中的某个目录，以便我们能直接使用该命令。

cp helm /usr/local/sbin/helm

2、安装服务端Tiller

然后安装Tiller，但是由于无法访问国外的网站，我们采用阿里云的镜像仓库。和上篇(使用kubeadm部署k8s 1.15集群——基于CentOS 7)一样，我们将tiller镜像拉取到本地，然后push到自己的本地私有镜像仓库。

docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/tiller:v2.14.1
docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/tiller:v2.14.1 192.168.0.200:80/kubernetes-helm/tiller:v2.14.1
docker push 192.168.0.200:80/kubernetes-helm/tiller:v2.14.1

因为我们集群开启了RBAC访问控制，所以也要为tiller创建ServiceAccount以及ClusterRoleBinding，使用以下配置文件helm-rabc-config.yaml，

apiVersion: v1
kind: ServiceAccount
metadata:
  name: tiller
  namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: tiller
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
  - kind: ServiceAccount
    name: tiller
    namespace: kube-system

之后使用kubectl创建该服务，并初始化该服务，使用tiller这个服务账号，设置最大历史版本为200个。

kubectl create -f helm-rabc-config.yaml
helm init --service-account tiller --history-max 200

创建完就可以查看下这个服务，

[root@CentOS-7-4 /home/k8s]# kubectl get pod -n kube-system -l name=tiller
NAME                             READY   STATUS    RESTARTS   AGE
tiller-deploy-5648cc8b79-68rmz   1/1     Running   0          25h
[root@CentOS-7-4 /home/k8s]# helm version
Client: &version.Version{SemVer:"v2.14.1", GitCommit:"5270352a09c7e8b6e8c9593002a73535276507c0", GitTreeState:"clean"}
Server: &version.Version{SemVer:"v2.14.1", GitCommit:"5270352a09c7e8b6e8c9593002a73535276507c0", GitTreeState:"clean"}

为了能够使用helm仓库，我们将helm的repo替换为阿里云的镜像仓库，

# 先移除原先的仓库
helm repo remove stable
# 添加阿里云仓库
helm repo add stable https://kubernetes.oss-cn-hangzhou.aliyuncs.com/charts
# 更新仓库
helm repo update

helm命令使用

helm和yum命令格式类似，其中有以下几个高频使用命令，

- helm search:    search for charts #在仓库中查询应用
- helm fetch:     download a chart to your local directory to view #下载应用安装包到本地
- helm install:   upload the chart to Kubernetes #安装应用到k8s集群中
- helm list:      list releases of charts #查看集群中已安装应用

更加详细和更多命令参数可使用helm help查看用户手册，

Available Commands:
  completion  Generate autocompletions script for the specified shell (bash or zsh)
  create      create a new chart with the given name
  delete      given a release name, delete the release from Kubernetes
  dependency  manage a chart's dependencies
  fetch       download a chart from a repository and (optionally) unpack it in local directory
  get         download a named release
  help        Help about any command
  history     fetch release history
  home        displays the location of HELM_HOME
  init        initialize Helm on both client and server
  inspect     inspect a chart
  install     install a chart archive
  lint        examines a chart for possible issues
  list        list releases
  package     package a chart directory into a chart archive
  plugin      add, list, or remove Helm plugins
  repo        add, list, remove, update, and index chart repositories
  reset       uninstalls Tiller from a cluster
  rollback    roll back a release to a previous revision
  search      search for a keyword in charts
  serve       start a local http web server
  status      displays the status of the named release
  template    locally render templates
  test        test a release
  upgrade     upgrade a release
  verify      verify that a chart at the given path has been signed and is valid
  version     print the client/server version information

参考

1、https://helm.sh/docs/using_helm/#quickstart-guide

2、https://helm.sh/docs/using_helm/#role-based-access-control