hello minikube

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文章记录minikube运行一个简单demo的流程，总结体会使用k8s的整体部署流程。

准备一个docker image

简单的http服务

package main

import (
    "fmt"
    "io"
    "log"
    "net/http"
)

func HelloServer(w http.ResponseWriter, req *http.Request) {
    io.WriteString(w, "hello, world!\n")
}

func main() {
    http.HandleFunc("/hello", HelloServer)

    fmt.Println("will listen on 12345")
    log.Fatal(http.ListenAndServe(":12345", nil))
}

Dockfile

FROM golang:1.11.5-alpine3.8 AS build
RUN mkdir -p $GOPATH/src/hello && mkdir -p /root/myapp
COPY . $GOPATH/src/hello
WORKDIR $GOPATH/src/hello
RUN go build -o /root/myapp/hello
CMD /root/myapp/hello

生成镜像并推送到docker hub

生成镜像

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docker build -t myapp .

为镜像打tag, 事先需要在docker hub上创建kbtest的项目。

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docker tag myapp guijiedocker/kbtest:myapp-v1

将镜像推送到docker hub的kbtest项目下

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docker push guijiedocker/kbtest:myapp-v1

setup minikube

1.创建minikube cluster

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minikube start

2.打开minikube dashboard

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minikube dashboard

3.创建deployment

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kubectl create deployment myapp --image=guijiedocker/kbtest:myapp-v1

4.查看deployment

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kubectl get deployments

输出:

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NAME    READY   UP-TO-DATE   AVAILABLE   AGE
myapp   1/1     1            1           24h

5.查看pod

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kubectl get pods

输出：

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Name:               myapp-579c5846dc-drmj5
Namespace:          default
Priority:           0
PriorityClassName:  <none>
Node:               minikube/10.0.2.15
Start Time:         Thu, 21 Feb 2019 17:18:58 +0800
Labels:             app=myapp
                    pod-template-hash=579c5846dc
Annotations:        <none>
Status:             Running
IP:                 172.17.0.2
Controlled By:      ReplicaSet/myapp-579c5846dc
Containers:
  kbtest:
    Container ID:   docker://0a725a3f5cf57c1eb23fb6b967e24e313593e5cc9034f3c85e4ec263692db283
    Image:          guijiedocker/kbtest:myapp-v1
    Image ID:       docker-pullable://guijiedocker/kbtest@sha256:79a4855a6fc532b9b194cbcccbaa55963dd13466e53b0d027eb44931b71a75e6
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Fri, 22 Feb 2019 16:31:15 +0800
    Last State:     Terminated
      Reason:       Error
      Exit Code:    255
      Started:      Thu, 21 Feb 2019 17:18:59 +0800
      Finished:     Fri, 22 Feb 2019 16:30:49 +0800
    Ready:          True
    Restart Count:  1
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-hw6bk (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             True
  ContainersReady   True
  PodScheduled      True
Volumes:
  default-token-hw6bk:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-hw6bk
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
                 node.kubernetes.io/unreachable:NoExecute for 300s
Events:          <none>

可以看出: 启动的pod的IP是172.17.0.2。(或者执行kubectl get pods -o wide) 但这个IP目前无法直接访问。它是集群内部的一个IP，需要进入到kubernate 节点中进行访问。 可运行：

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minikube ssh

进入kubernates Node之后，ping 172.17.0.2，测试到pod的连通性。然后执行:

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curl 'http://172.17.0.2:12345/hello'

6.创建service

外部如何访问到myapp服务？kubernetes默认方案是在deployment基础之上又抽象出了service这个组件。执行:

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kubectl expose deployment myapp --type=LoadBalancer --port 12345

以上命令中的port要跟我们服务的监听端口一致。

7.查看外部访问端口

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kubectl get service myapp

输出: NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE myapp LoadBalancer 10.100.146.178 12345:30173/TCP 5m50s

或者,更直观一点:

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minikube service myapp --url

输出: http://192.168.99.100:30173

测试请求：

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curl 'http://192.168.99.100:30173/hello'