前言
由于K8s的资源声明式API，所有的资源通过定义Yaml来管理；资源类型众多，如 Service Deployment Ingress等，从一个具体对外提供服务的应用的视角来看，这些资源之间相互依赖，因此我们将它们抽象出来统称为应用。因此应用本质上就是一堆相关联的yaml文件的集合。而这堆yaml之间存在着很多相同的共性，例如Deployment与Service的Name；或是有些变量我们需要抽象出来放在一个配置文件中，方便安装或是升级，如Deployment的Replicas副本数量。这就是Helm chart的来源。
Helm安装
$ brew install helm
$ helm version
...
version.BuildInfo{Version:"v3.4.1", GitCommit:"c4e74854886b2efe3321e185578e6db9be0a6e29", GitTreeState:"dirty", GoVersion:"go1.15.4"}
制作第一个Chart包
$ helm create hello-world
WARNING: Kubernetes configuration file is group-readable. This is insecure. Location: /Users/hugo/.kube/config
WARNING: Kubernetes configuration file is world-readable. This is insecure. Location: /Users/hugo/.kube/config
Creating hello-world
可以看到第一个初始化的包已经制作出来了
$ tree .
.
└── hello-world
├── Chart.yaml # Chart及应用版本信息
├── charts # 依赖的Charts
├── templates
│ ├── NOTES.txt # 输出安装完后的提示信息
│ ├── _helpers.tpl # 内部的变量及条件判断逻辑
│ ├── deployment.yaml
│ ├── hpa.yaml
│ ├── ingress.yaml
│ ├── service.yaml
│ ├── serviceaccount.yaml
│ └── tests
│ └── test-connection.yaml
└── values.yaml # 自定义的变量，如副本数、镜像等
看下values.yaml的信息，如果要修改默认值，可以在安装的时候加上--set
replicaCount: 1
image:
repository: nginx
...
检验包
$ helm lint hello-world
WARNING: Kubernetes configuration file is group-readable. This is insecure. Location: /Users/hugo/.kube/config
WARNING: Kubernetes configuration file is world-readable. This is insecure. Location: /Users/hugo/.kube/config
==> Linting hello-world
[INFO] Chart.yaml: icon is recommended
1 chart(s) linted, 0 chart(s) failed
打包
$ helm package hello-world hello-world
WARNING: Kubernetes configuration file is group-readable. This is insecure. Location: /Users/hugo/.kube/config
WARNING: Kubernetes configuration file is world-readable. This is insecure. Location: /Users/hugo/.kube/config
Successfully packaged chart and saved it to: /tmp/test/hello-world-0.1.0.tgz
Successfully packaged chart and saved it to: /tmp/test/hello-world-0.1.0.tgz
安装
$ helm install hello-world hello-world-0.1.0.tgz
WARNING: Kubernetes configuration file is group-readable. This is insecure. Location: /Users/hugo/.kube/config
WARNING: Kubernetes configuration file is world-readable. This is insecure. Location: /Users/hugo/.kube/config
NAME: hello-world
LAST DEPLOYED: Fri Nov 20 11:28:45 2020
NAMESPACE: xxx
STATUS: deployed
REVISION: 1
NOTES:
1. Get the application URL by running these commands:
export POD_NAME=$(kubectl get pods --namespace xxx -l "app.kubernetes.io/name=hello-world,app.kubernetes.io/instance=hello-world" -o jsonpath="{.items[0].metadata.name}")
export CONTAINER_PORT=$(kubectl get pod --namespace xxx $POD_NAME -o jsonpath="{.spec.containers[0].ports[0].containerPort}")
echo "Visit http://127.0.0.1:8080 to use your application"
kubectl --namespace xxx port-forward $POD_NAME 8080:$CONTAINER_PORT
此时应用已经安装完成
$ kubectl get po
NAME READY STATUS RESTARTS AGE
hello-world-75c474b897-tfprp 1/1 Running 0 72s
上面的输出信息提供了三个步骤，分别是获取Pod Name，获取Pod的暴露端口，将这个端口暴露到外部
将这个pod 端口暴露看下效果
$ kubectl port-forward hello-world-75c474b897-tfprp 8080:80
Forwarding from 127.0.0.1:8080 -> 80
Forwarding from [::1]:8080 -> 80
访问正常
$ curl http://localhost:8080
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
body {
width: 35em;
margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif;
}
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>