学习视频： https://www.bilibili.com/video/BV13Q4y1C7hS?p=41&vd_source=0bf662c33adfc181186b04ba57e11dff
附带笔记： https://www.yuque.com/leifengyang/oncloud/kgheaf

命名空间Namespace

3台机器， 将相同功能的模块放到同一名为prod的命名空间或者是dev命名空间

[root@k8s-master ~]# kubectl get ns
NAME                   STATUS   AGE
default                Active   173m
kube-node-lease        Active   173m
kube-public            Active   173m
kube-system            Active   173m
kubernetes-dashboard   Active   87m

[root@k8s-master ~]# kubectl create ns hello
namespace/hello created
[root@k8s-master ~]# kubectl get ns hello
NAME    STATUS   AGE
hello   Active   7s

删除

[root@k8s-master ~]# kubectl delete ns hello
namespace "hello" deleted

Pod

容器外有封装了一层



红圈内是pod内应用的总数

命令行创建一个pod（名为mynginx从nginx的镜像中拉取的）

[root@k8s-master ~]# kubectl run mynginx --image=nginx
pod/mynginx created
[root@k8s-master ~]# kubectl get pod
NAME      READY   STATUS              RESTARTS   AGE
mynginx   0/1     ContainerCreating   0          67s
#容器还在下载

查看

[root@k8s-master ~]# kubectl describe pod mynginx
Name:         mynginx
Namespace:    default
Priority:     0
Node:         k8s-1/192.168.23.244
Start Time:   Tue, 12 Jul 2022 12:49:25 +0800
Labels:       run=mynginx
Annotations:  cni.projectcalico.org/containerID: b03938a1f495e4879bc35a1c426f5aa5465acabfa7da25f79a864a5a169b13df
              cni.projectcalico.org/podIP: 193.168.231.194/32
              cni.projectcalico.org/podIPs: 193.168.231.194/32
Status:       Running
IP:           193.168.231.194
IPs:
  IP:  193.168.231.194
Containers:
  mynginx:
    Container ID:   docker://cc97ab264f2cb93e88f61b3ce19ec81f39c3aabbcdd1a8ddb30bd6afb0abd275
    Image:          nginx
    Image ID:       docker-pullable://nginx@sha256:0d17b565c37bcbd895e9d92315a05c1c3c9a29f762b011a10c54a66cd53c9b31
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Tue, 12 Jul 2022 12:50:36 +0800
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-lhbbl (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             True
  ContainersReady   True
  PodScheduled      True
Volumes:
  default-token-lhbbl:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-lhbbl
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
                 node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
  Type    Reason     Age        From               Message
  ----    ------     ----       ----               -------
  Normal  Scheduled  2m40s      default-scheduler  Successfully assigned default/mynginx to k8s-1
  Normal  Pulling    <invalid>  kubelet            Pulling image "nginx"
  Normal  Pulled     <invalid>  kubelet            Successfully pulled image "nginx" in 1m8.550718578s
  Normal  Created    <invalid>  kubelet            Created container mynginx
  Normal  Started    <invalid>  kubelet            Started container mynginx

注意上方Events的模块右侧的Message,我们发现任务被分配到k8s-01上执行，我们在docker查看如下

等一会儿发现成功

相关命令

# 查看default名称空间的Pod
kubectl get pod 
# 描述
kubectl describe pod 你自己的Pod名字
# 删除
kubectl delete pod Pod名字
# 查看Pod的运行日志
kubectl logs Pod名字

# 每个Pod - k8s都会分配一个ip
kubectl get pod -owide
# 使用Pod的ip+pod里面运行容器的端口
curl 192.168.169.136

# 集群中的任意一个机器以及任意的应用都能通过Pod分配的ip来访问这个Pod

进入docker命令行

[root@k8s-master ~]# kubectl exec -it mynginx -- /bin/bash
root@mynginx:/# ls
bin   dev                  docker-entrypoint.sh  home  lib64  mnt  proc  run   srv  tmp  var
boot  docker-entrypoint.d  etc                   lib   media  opt  root  sbin  sys  usr

也可以用yaml方法创建，我们可以在官网和虚拟机编写，

下面以官网部署多容器pod为例：

apiVersion: v1
kind: Pod
metadata:
  labels:
    run: myapp
  name: myapp
spec:
  containers:
  - image: nginx
    name: nginx
  - image: tomcat:8.5.68
    name: tomcat

黄色表面左边的myapp而右边的mynginx还在安装，我们看看可视化界面的events块，如出一辙

等了一会 绿了


可以通过不同的端口curl到不同的软件

[root@k8s-1 ~]# curl 193.168.200.194:8080
<!doctype html><html lang="en"><head><title>HTTP Status 404 – Not Found</title><style type="text/css">body {font-family:Tahoma,Arial,sans-serif;} h1, h2, h3, b {color:white;background-color:#525D76;} h1 {font-size:22px;} h2 {font-size:16px;} h3 {font-size:14px;} p {font-size:12px;} a {color:black;} .line {height:1px;background-color:#525D76;border:none;}</style></head><body><h1>HTTP Status 404 – Not Found</h1><hr class="line" /><p><b>Type</b> Status Report</p><p><b>Description</b> The origin server did not find a current representation for the target resource or is not willing to disclose that one exists.</p><hr class="line" /><h3>Apache Tomcat/8.5.68</h3></body></html>


[root@k8s-1 ~]# curl 193.168.200.194:80
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
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>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>

这就是我们目前pod的结构

Dashboard 端pod界面选择exec（执行）选项可以选择执行那个应用

同一个pod可以本机内访问

---

如果同一个pod理由两个nginx，端口会冲突导致error

Deployment

控制Pod，使Pod拥有多副本，自愈，扩缩容等能力

删除前两个pod

kubectl delete -n default pod myapp mynginx

开新pod

[root@k8s-master ~]# kubectl run mynginx --image=nginx
pod/mynginx created

[root@k8s-master ~]# kubectl get pod
NAME      READY   STATUS    RESTARTS   AGE
mynginx   1/1     Running   0          45s

[root@k8s-master ~]# kubectl create deployment mytomcat --image=tomcat:8.5.68
deployment.apps/mytomcat created

[root@k8s-master ~]# kubectl get pod
NAME                        READY   STATUS    RESTARTS   AGE
mynginx                     1/1     Running   0          75s
mytomcat-6f5f895f4f-z8vmp   1/1     Running   0          18s

自愈
把两个删了对比下，看看k8s强大的自愈能力

对比正常删除的mynginx，虽然我们删了第一个tomcat的pod，但他立马生产了另一个新的tomcat的pod

如果要真正彻底删除，我们要把deploy本身删去如下：

[root@k8s-master ~]# kubectl get pod
NAME                        READY   STATUS    RESTARTS   AGE
mytomcat-6f5f895f4f-dwjgd   1/1     Running   0          4m8s
[root@k8s-master ~]# kubectl get deploy
NAME       READY   UP-TO-DATE   AVAILABLE   AGE
mytomcat   1/1     1            1           7m22s
[root@k8s-master ~]# kubectl delete deploy mytomcat
deployment.apps "mytomcat" deleted

多副本能力

把同一个pod部署多次

[root@k8s-master ~]# kubectl create deploy my-dep --image=nginx --replicas=3
deployment.apps/my-dep created
[root@k8s-master ~]# kubectl get pod
NAME                      READY   STATUS              RESTARTS   AGE
my-dep-5b7868d854-2ccwg   1/1     Running             0          7s
my-dep-5b7868d854-jc7jc   0/1     ContainerCreating   0          7s
my-dep-5b7868d854-mv7h2   0/1     ContainerCreating   0          7s
[root@k8s-master ~]# kubectl get deploy
NAME     READY   UP-TO-DATE   AVAILABLE   AGE
my-dep   3/3     3            3           34s

我们在Dashboard看看

[root@k8s-master ~]# kubectl delete deploy my-dep

也可以在dashpod设置

Deployment的扩缩容

先准备如下deployment

[root@k8s-master ~]# kubectl create deploy my-dep --image=nginx --replicas=3
deployment.apps/my-dep created

扩容到5个

[root@k8s-master ~]# kubectl scale --replicas=5 deploy/my-dep
deployment.apps/my-dep scaled
[root@k8s-master ~]# kubectl get deploy my-dep
NAME     READY   UP-TO-DATE   AVAILABLE   AGE
my-dep   3/5     5            3           3m17s

缩容到2个

[root@k8s-master ~]# kubectl scale --replicas=2 deploy/my-dep
deployment.apps/my-dep scaled
[root@k8s-master ~]# kubectl get deploy my-dep
NAME     READY   UP-TO-DATE   AVAILABLE   AGE
my-dep   2/2     2            2           4m18s

dashboard如下操作

自愈能力与故障转移能力

准备如下

[root@k8s-master ~]# kubectl create deploy my-dep --image=nginx --replicas=3
deployment.apps/my-dep created
[root@k8s-master ~]# kubectl get pod -owide
NAME                      READY   STATUS    RESTARTS   AGE   IP                NODE    NOMINATED NODE   READINESS GATES
my-dep-5b7868d854-4ztqg   1/1     Running   0          27s   193.168.200.200   k8s-2   <none>           <none>
my-dep-5b7868d854-6wbxc   1/1     Running   0          27s   193.168.231.202   k8s-1   <none>           <none>
my-dep-5b7868d854-9z5hn   1/1     Running   0          27s   193.168.200.199   k8s-2   <none>           <none>

自愈能力

我们发现my-dep-5b7868d854-6wbxc这个pod在k8s-1机器上，所以我们去k8s-1上关闭my-dep-5b7868d854-6wbxc模拟pod意外关闭

[root@k8s-1 ~]# docker ps |grep my-dep-5b7868d854-6wbxc
01c0dbbb3565   nginx                                                        "/docker-entrypoint.…"   3 minutes ago   Up 3 minutes             k8s_nginx_my-dep-5b7868d854-6wbxc_default_390d6af1-43bf-4649-9e94-213b0823a973_0
3da3039032de   registry.cn-hangzhou.aliyuncs.com/lfy_k8s_images/pause:3.2   "/pause"                 3 minutes ago   Up 3 minutes             k8s_POD_my-dep-5b7868d854-6wbxc_default_390d6af1-43bf-4649-9e94-213b0823a973_0

[root@k8s-1 ~]# docker stop 01c0dbbb3565
01c0dbbb3565

回到Master节点，发现被我们stop的pod已经关闭并重新期待至ready状态栏

故障转移能力

[root@k8s-master ~]# kubectl get pod -owide
NAME                      READY   STATUS    RESTARTS   AGE   IP                NODE    NOMINATED NODE   READINESS GATES
my-dep-5b7868d854-4ztqg   1/1     Running   0          11m   193.168.200.200   k8s-2   <none>           <none>
my-dep-5b7868d854-6wbxc   1/1     Running   1          11m   193.168.231.202   k8s-1   <none>           <none>
my-dep-5b7868d854-9z5hn   1/1     Running   0          11m   193.168.200.199   k8s-2   <none>           <none>


[root@k8s-1 ~]# docker ps |grep my-dep-5b7868d854-6wbxc
2146ec490097   nginx                                                        "/docker-entrypoint.…"   4 minutes ago   Up 4 minutes             k8s_nginx_my-dep-5b7868d854-6wbxc_default_390d6af1-43bf-4649-9e94-213b0823a973_1
3da3039032de   registry.cn-hangzhou.aliyuncs.com/lfy_k8s_images/pause:3.2   "/pause"                 9 minutes ago   Up 9 minutes             k8s_POD_my-dep-5b7868d854-6wbxc_default_390d6af1-43bf-4649-9e94-213b0823a973_0

同样的，我们发现my-dep-5b7868d854-6wbxc这个pod在k8s-1机器上，所以我们直接关闭k8s-1模拟宕机

[root@k8s-1 ~]# shutdown

在主节点开启监控

[root@k8s-master ~]# kubectl get pod -w

同时 如下

[root@k8s-master ~]# kubectl get pod -owide
NAME                      READY   STATUS        RESTARTS   AGE     IP                NODE    NOMINATED NODE   READINESS GATES
my-dep-5b7868d854-4ztqg   1/1     Running       0          29m     193.168.200.200   k8s-2   <none>           <none>
my-dep-5b7868d854-6wbxc   1/1     Terminating   1          29m     193.168.231.202   k8s-1   <none>           <none>
my-dep-5b7868d854-9z5hn   1/1     Running       0          29m     193.168.200.199   k8s-2   <none>           <none>
my-dep-5b7868d854-lq2tq   1/1     Running       0          9m22s   193.168.200.201   k8s-2   <none>           <none>

[root@k8s-master ~]# kubectl get pod -owide
NAME                      READY   STATUS    RESTARTS   AGE   IP                NODE    NOMINATED NODE   READINESS GATES
my-dep-5b7868d854-4ztqg   1/1     Running   0          41m   193.168.200.200   k8s-2   <none>           <none>
my-dep-5b7868d854-9z5hn   1/1     Running   0          41m   193.168.200.199   k8s-2   <none>           <none>
my-dep-5b7868d854-lq2tq   1/1     Running   0          21m   193.168.200.201   k8s-2   <none> 

我们发现被关闭的pod转移到了k8s-02机器上

滚动更新

不停机更新，等一台机器更新完在更新下一台

准备如下

[root@k8s-master ~]# kubectl scale --replicas=4 deploy/my-dep
deployment.apps/my-dep scaled

将版本更新为nginx:1.16.1 ，同时开启监控

[root@k8s-master ~]# kubectl set image deploy/my-dep nginx=nginx:1.16.1 --record
deployment.apps/my-dep image updated

[root@k8s-master ~]# kubectl get pod -w

通过监控我们发现是滚动更新（逐台杀老机器启新机器）

版本回退

#历史记录
[root@k8s-master ~]# kubectl rollout history deployment/my-dep
deployment.apps/my-dep
REVISION  CHANGE-CAUSE
1         <none>
2         kubectl set image deploy/my-dep nginx=nginx:1.16.1 --record=true



#查看某个历史详情
[root@k8s-master ~]# kubectl rollout history deployment/my-dep --revision=2
deployment.apps/my-dep with revision #2
Pod Template:
  Labels:       app=my-dep
        pod-template-hash=6b48cbf4f9
  Annotations:  kubernetes.io/change-cause: kubectl set image deploy/my-dep nginx=nginx:1.16.1 --record=true
  Containers:
   nginx:
    Image:      nginx:1.16.1
    Port:       <none>
    Host Port:  <none>
    Environment:        <none>
    Mounts:     <none>
  Volumes:      <none>


#回滚(回到上次)
kubectl rollout undo deployment/my-dep

#回滚(回到指定版本)
[root@k8s-master ~]# kubectl rollout undo deployment/my-dep --to-revision=1
deployment.apps/my-dep rolled back
[root@k8s-master ~]# kubectl rollout history deployment/my-dep
deployment.apps/my-dep
REVISION  CHANGE-CAUSE
2         kubectl set image deploy/my-dep nginx=nginx:1.16.1 --record=true
3         <none>

更多：
除了Deployment，k8s还有 StatefulSet 、DaemonSet 、Job  等 类型资源。我们都称为 工作负载。
有状态应用使用  StatefulSet  部署，无状态应用使用 Deployment 部署
https://kubernetes.io/zh/docs/concepts/workloads/controllers/