Helm

Helm 是一个类似于 yum/apt/homebrew 的 Kubernetes 应用管理工具。Helm 使用 Chart 来管理 Kubernetes manifest 文件。

Helm 基本使用

安装 helm 客户端

brew install kubernetes-helm

初始化 Helm 并安装 Tiller 服务(需要事先配置好 kubectl)

helm init

更新 charts 列表

helm repo update

部署服务,比如 mysql

➜  ~ helm install stable/mysql
NAME:   quieting-warthog
LAST DEPLOYED: Tue Feb 21 16:13:02 2017
NAMESPACE: default
STATUS: DEPLOYED

RESOURCES:
==> v1/Secret
NAME                    TYPE    DATA  AGE
quieting-warthog-mysql  Opaque  2     1s

==> v1/PersistentVolumeClaim
NAME                    STATUS   VOLUME  CAPACITY  ACCESSMODES  AGE
quieting-warthog-mysql  Pending  1s

==> v1/Service
NAME                    CLUSTER-IP    EXTERNAL-IP  PORT(S)   AGE
quieting-warthog-mysql  10.3.253.105  <none>       3306/TCP  1s

==> extensions/v1beta1/Deployment
NAME                    DESIRED  CURRENT  UP-TO-DATE  AVAILABLE  AGE
quieting-warthog-mysql  1        1        1           0          1s


NOTES:
MySQL can be accessed via port 3306 on the following DNS name from within your cluster:
quieting-warthog-mysql.default.svc.cluster.local

To get your root password run:

    kubectl get secret --namespace default quieting-warthog-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 quieting-warthog-mysql -p

更多命令的使用方法可以参考 Helm 命令参考

Helm 工作原理

基本概念

Helm 的三个基本概念

  • Chart:Helm 应用(package),包括该应用的所有 Kubernetes manifest 模版,类似于 YUM RPM 或 Apt dpkg 文件
  • Repository:Helm package 存储仓库
  • Release:chart 的部署实例,每个 chart 可以部署一个或多个 release

Helm 工作原理

Helm 包括两个部分,helm 客户端和 tiller 服务端。

the client is responsible for managing charts, and the server is responsible for managing releases.

helm 客户端

helm 客户端是一个命令行工具,负责管理 charts、repository 和 release。它通过 gPRC API(使用 kubectl port-forward 将 tiller 的端口映射到本地,然后再通过映射后的端口跟 tiller 通信)向 tiller 发送请求,并由 tiller 来管理对应的 Kubernetes 资源。

Helm 客户端的使用方法参见 Helm 命令

tiller 服务端

tiller 接收来自 helm 客户端的请求,并把相关资源的操作发送到 Kubernetes,负责管理(安装、查询、升级或删除等)和跟踪 Kubernetes 资源。为了方便管理,tiller 把 release 的相关信息保存在 kubernetes 的 ConfigMap 中。

tiller 对外暴露 gRPC API,供 helm 客户端调用。

Helm Charts

Helm 使用 Chart 来管理 Kubernetes manifest 文件。每个 chart 都至少包括

  • 应用的基本信息 Chart.yaml
  • 一个或多个 Kubernetes manifest 文件模版(放置于 templates / 目录中),可以包括 Pod、Deployment、Service 等各种 Kubernetes 资源

Chart.yaml 示例

name: The name of the chart (required)
version: A SemVer 2 version (required)
description: A single-sentence description of this project (optional)
keywords:
  - A list of keywords about this project (optional)
home: The URL of this project's home page (optional)
sources:
  - A list of URLs to source code for this project (optional)
maintainers: # (optional)
  - name: The maintainer's name (required for each maintainer)
    email: The maintainer's email (optional for each maintainer)
engine: gotpl # The name of the template engine (optional, defaults to gotpl)
icon: A URL to an SVG or PNG image to be used as an icon (optional).

依赖管理

Helm 支持两种方式管理依赖的方式:

  • 直接把依赖的 package 放在 charts/ 目录中
  • 使用 requirements.yaml 并用 helm dep up foochart 来自动下载依赖的 packages
dependencies:
  - name: apache
    version: 1.2.3
    repository: http://example.com/charts
  - name: mysql
    version: 3.2.1
    repository: http://another.example.com/charts

Chart 模版

Chart 模板基于 Go template 和 Sprig,比如

apiVersion: v1
kind: ReplicationController
metadata:
  name: deis-database
  namespace: deis
  labels:
    heritage: deis
spec:
  replicas: 1
  selector:
    app: deis-database
  template:
    metadata:
      labels:
        app: deis-database
    spec:
      serviceAccount: deis-database
      containers:
        - name: deis-database
          image: {{.Values.imageRegistry}}/postgres:{{.Values.dockerTag}}
          imagePullPolicy: {{.Values.pullPolicy}}
          ports:
            - containerPort: 5432
          env:
            - name: DATABASE_STORAGE
              value: {{default "minio" .Values.storage}}

模版参数的默认值必须放到 values.yaml 文件中,其格式为

imageRegistry: "quay.io/deis"
dockerTag: "latest"
pullPolicy: "alwaysPull"
storage: "s3"

# 依赖的 mysql chart 的默认参数
mysql:
  max_connections: 100
  password: "secret"

Helm 插件

插件提供了扩展 Helm 核心功能的方法,它在客户端执行,并放在 $(helm home)/plugins 目录中。

一个典型的 helm 插件格式为

$(helm home)/plugins/
  |- keybase/
      |
      |- plugin.yaml
      |- keybase.sh

而 plugin.yaml 格式为

name: "keybase"
version: "0.1.0"
usage: "Integreate Keybase.io tools with Helm"
description: |-
  This plugin provides Keybase services to Helm.
ignoreFlags: false
useTunnel: false
command: "$HELM_PLUGIN_DIR/keybase.sh"

这样,就可以用 helm keybase 命令来使用这个插件。

Helm 命令参考

查询 charts

helm search
helm search mysql

查询 package 详细信息

helm inspect stable/mariadb

部署 package

helm install stable/mysql

部署之前可以自定义 package 的选项:

# 查询支持的选项
helm inspect values stable/mysql

# 自定义 password
echo "mysqlRootPassword: passwd" > config.yaml
helm install -f config.yaml stable/mysql

另外,还可以通过打包文件(.tgz)或者本地 package 路径(如 path/foo)来部署应用。

查询服务 (Release) 列表

➜  ~ helm ls
NAME                REVISION    UPDATED                     STATUS      CHART          NAMESPACE
quieting-warthog    1           Tue Feb 21 20:13:02 2017    DEPLOYED    mysql-0.2.5    default

查询服务 (Release) 状态

➜  ~ helm status quieting-warthog
LAST DEPLOYED: Tue Feb 21 16:13:02 2017
NAMESPACE: default
STATUS: DEPLOYED

RESOURCES:
==> v1/Secret
NAME                    TYPE    DATA  AGE
quieting-warthog-mysql  Opaque  2     9m

==> v1/PersistentVolumeClaim
NAME                    STATUS  VOLUME                                    CAPACITY  ACCESSMODES  AGE
quieting-warthog-mysql  Bound   pvc-90af9bf9-f80d-11e6-930a-42010af00102  8Gi       RWO          9m

==> v1/Service
NAME                    CLUSTER-IP    EXTERNAL-IP  PORT(S)   AGE
quieting-warthog-mysql  10.3.253.105  <none>       3306/TCP  9m

==> extensions/v1beta1/Deployment
NAME                    DESIRED  CURRENT  UP-TO-DATE  AVAILABLE  AGE
quieting-warthog-mysql  1        1        1           1          9m


NOTES:
MySQL can be accessed via port 3306 on the following DNS name from within your cluster:
quieting-warthog-mysql.default.svc.cluster.local

To get your root password run:

    kubectl get secret --namespace default quieting-warthog-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 quieting-warthog-mysql -p

升级和回滚 Release

# 升级
cat "mariadbUser: user1" >panda.yaml
helm upgrade -f panda.yaml happy-panda stable/mariadb

# 回滚
helm rollback happy-panda 1

删除 Release

helm delete quieting-warthog

repo 管理

# 添加 incubator repo
helm repo add incubator https://kubernetes-charts-incubator.storage.googleapis.com/

# 查询 repo 列表
helm repo list

# 生成 repo 索引(用于搭建 helm repository)
helm repo index

chart 管理

# 创建一个新的 chart
helm create deis-workflow

# validate chart
helm lint

# 打包 chart 到 tgz
helm package deis-workflow

Helm UI

Kubeapps 提供了一个开源的 Helm UI 界面,方便以图形界面的形式管理 Helm 应用。

curl -s https://api.github.com/repos/kubeapps/kubeapps/releases/latest | grep -i $(uname -s) | grep browser_download_url | cut -d '"' -f 4 | wget -i -
sudo mv kubeapps-$(uname -s| tr '[:upper:]' '[:lower:]')-amd64 /usr/local/bin/kubeapps
sudo chmod +x /usr/local/bin/kubeapps

kubeapps up
kubeapps dashboard

更多使用方法请参考 Kubeapps 官方网站

Helm Repository

官方 repository:

第三方 repository:

常用 Helm 插件

  1. helm-tiller - Additional commands to work with Tiller
  2. Technosophos's Helm Plugins - Plugins for GitHub, Keybase, and GPG
  3. helm-template - Debug/render templates client-side
  4. Helm Value Store - Plugin for working with Helm deployment values
  5. Drone.io Helm Plugin - Run Helm inside of the Drone CI/CD system
© Pengfei Ni all right reserved,powered by GitbookUpdated at 2018-08-13 08:16:52

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