【kubernetes/k8s概念】Helm chart

客官°小女子只卖身不卖艺 2022-09-03 04:29 235阅读 0赞

Helm 是 Kubernetes 的包管理工具，类似与 Linux 的包管理器，如 RedHat 系的 yum，可以方便的将打包好的 yaml 文件部署到 Kubernetes 上。

Helm主要解决以下问题：

>  *    把 yaml 文件作为一个整体管理
>  *    实现 yaml 的高效复用
>  *    实现应用级别的版本管理

**    Helm 有3个重要概念：**

>  *      helm： 命令行工具，主要用于 Kubernetes 应用 chart 的创建、 打包、 发布和管理
>  *      Chart：应用描述，一系列用于描述 k8s 资源相关文件的集合
>  *      Release：基于 Chart 的部署实体，一个 chart 被 Helm 运行后将会生成对应的一个release；release是在 k8s 中创建出真实运行的资源对象。

Helm 命令行：

>     # helm repo update   # 更新repo仓库
>     # helm repo list   # 查看当前使用的仓库
>     # helm repo add xxx   # 添加repo地址
>     # helm search  xxx  # 搜索应用
>     # helm inspect xxx  # 查看chart的信息，会把chart下载到本地
>     # helm install xxx  # 安装chart
>     # helm delete  xxx  # 删除release
>     # helm upgrade/rollback  xxx # 升级/回滚
>     # helm list  # 列出release
>     更多用法可以使用 helm --help 查询

# 1. Chart 目录结构 #

├── charts
    ├── Chart.yaml
    ├── templates
    │   ├── deployment.yaml
    │   ├── _helpers.tpl
    │   ├── hpa.yaml
    │   ├── ingress.yaml
    │   ├── NOTES.txt
    │   ├── serviceaccount.yaml
    │   ├── service.yaml
    │   └── tests
    │       └── test-connection.yaml
    └── values.yaml

###    1.1 charts ###

该目录是可选的，该目录中放置当前 Chart 依赖的其它 Chart，比如 kubefed

├── charts
    │   └── controllermanager
    │       ├── Chart.yaml
    │       ├── crds
    │       │   └── crds.yaml
    │       └── templates
    │           ├── aggregate_clusterroles.yaml
    │           ├── clusterrolebindings.yaml
    │           ├── clusterrole.yaml
    │           ├── deployments.yaml
    │           ├── _helpers.tpl
    │           ├── kubefedconfig.yaml
    │           ├── post-install-job.yaml
    │           ├── rolebindings.yaml
    │           ├── roles.yaml
    │           ├── serviceaccounts.yaml
    │           ├── service.yaml
    │           └── webhook.yaml

###    1.2 Chart.yaml ###

描述这个 Chart 的相关信息、包括名字、描述信息、版本等

> apiVersion: v2  
> name: my-chart  
> description: A Helm chart for Kubernetes
> 
> \# A chart can be either an 'application' or a 'library' chart.  
> \#  
> \# Application charts are a collection of templates that can be packaged into versioned archives  
> \# to be deployed.  
> \#  
> \# Library charts provide useful utilities or functions for the chart developer. They're included as  
> \# a dependency of application charts to inject those utilities and functions into the rendering  
> \# pipeline. Library charts do not define any templates and therefore cannot be deployed.  
> type: application
> 
> \# This is the chart version. This version number should be incremented each time you make changes  
> \# to the chart and its templates, including the app version.  
> \# Versions are expected to follow Semantic Versioning (https://semver.org/)  
> version: 0.1.0
> 
> \# This is the version number of the application being deployed. This version number should be  
> \# incremented each time you make changes to the application. Versions are not expected to  
> \# follow Semantic Versioning. They should reflect the version the application is using.  
> \# It is recommended to use it with quotes.  
> appVersion: "1.16.0"

###    1.3 templates ###

templates 目录用于部署模板文件。 当 Helm 收集这些模板的结果，模版使用的值来自 values.yaml 并将它们发送到 Kubernetes。比如 service.yaml，deployment.yaml 内容太多

> apiVersion: v1  
> kind: Service  
> metadata:  
>   name: \{ \{ include "my-chart.fullname" . \}\}  
>   labels:  
>     \{ \{- include "my-chart.labels" . | nindent 4 \}\}  
> spec:  
>   type: \{ \{ .Values.service.type \}\}  
>   ports:  
>     - port: \{ \{ .Values.service.port \}\}  
>       targetPort: http  
>       protocol: TCP  
>       name: http  
>   selector:  
>     \{ \{- include "my-chart.selectorLabels" . | nindent 4 \}\}

###    1.4 values.yaml ###

values.yaml 文件对于模板也很重要。 此文件包含 chart 的默认值。 这些值可能会在 helm 安装或 helm 升级期间被用户覆盖。

> \# Default values for my-chart.  
> \# This is a YAML-formatted file.  
> \# Declare variables to be passed into your templates.
> 
> replicaCount: 1
> 
> image:  
>   repository: nginx  
>   pullPolicy: IfNotPresent  
>   \# Overrides the image tag whose default is the chart appVersion.  
>   tag: ""
> 
> imagePullSecrets: \[\]  
> nameOverride: ""  
> fullnameOverride: ""
> 
> serviceAccount:  
>   \# Specifies whether a service account should be created  
>   create: true  
>   \# Annotations to add to the service account  
>   annotations: \{\}  
>   \# The name of the service account to use.  
>   \# If not set and create is true, a name is generated using the fullname template  
>   name: ""
> 
> podAnnotations: \{\}
> 
> podSecurityContext: \{\}  
>   \# fsGroup: 2000
> 
> securityContext: \{\}  
>   \# capabilities:  
>   \#   drop:  
>   \#   - ALL  
>   \# readOnlyRootFilesystem: true  
>   \# runAsNonRoot: true  
>   \# runAsUser: 1000
> 
> service:  
>   type: ClusterIP  
>   port: 80  
>

## 检查配置和模板 ##

>     helm install my-chart --dry-run --debug ./

参考：

[https://helm.sh/docs/topics/charts/][https_helm.sh_docs_topics_charts]

[https_helm.sh_docs_topics_charts]: https://helm.sh/docs/topics/charts/