【三】K8S_NameSpace和Pod

2023-9-17

一、NameSpace

Kubernetes（K8S）中的 Namespace 是一种用于组织和隔离集群资源的方式。它具有以下用途和相关概念：

  1. 资源隔离：Namespace 提供资源隔离与命名空间划分。它将整个集群划分为多个逻辑部分，每个部分称为一个 Namespace。不同 Namespace 中的资源相互隔离，避免了资源名称冲突以及不同应用之间的干扰。
  2. 多租户支持：通过 Namespace，K8S 能够实现多租户的支持。每个租户可以拥有自己的 Namespace，并能够独立管理和使用属于自己的资源。这有助于在一个集群中同时运行多个不同的应用或团队，并提供更好的资源管理和访问控制。
  3. 访问控制：Namespace 可以用来进行访问控制和权限管理。您可以为每个 Namespace 配置不同的 RBAC（Role-Based Access Control）策略，从而控制用户或组对该 Namespace 内资源的访问权限。这样可以确保不同团队或应用之间的资源隔离和安全性。
  4. 可视化和监控：Namespace 可以用于帮助可视化和监控集群中不同应用程序的资源使用情况。通过将不同应用程序的资源分配到不同的 Namespace 中，您可以更方便地查看和监控每个应用程序的资源消耗情况，并做出相应的优化和调整。
  5. 环境隔离：Namespace 可以用于在开发、测试和生产环境之间实现逻辑隔离。每个环境可以使用不同的 Namespace，使得不同环境中的资源相互独立。这样能够更好地管理和控制不同环境中的应用程序和配置。
  6. 资源限额：Namespace 允许您为每个 Namespace 设置资源限额，以控制其使用的 CPU、内存和存储等资源。这有助于避免某个应用程序占用过多资源导致其他应用受影响，提高集群的稳定性和可靠性。

通过使用 Namespace，您可以有效地组织、隔离和管理 Kubernetes 集群中的资源。它提供了一种灵活而强大的方式来划分和控制不同应用程序和团队的资源，并帮助实现多租户支持、访问控制、环境隔离等功能。

 

[root@master ~]# kubectl create ns dev
namespace/dev created
【三】K8S_NameSpace和Pod插图

二、Pod

运行中的一组容器，Pod是kuberneres中应用的最小单位
【1】命令式对象管理: 直接使用命令去操作kubernetes资源

[root@k8s-master ~]# kubectl get  pod -A
NAMESPACE      NAME                                 READY   STATUS    RESTARTS   AGE
default        nginx-598f5c449-bdzdm                1/1     Running   0          25m
kube-flannel   kube-flannel-ds-hxwjt                1/1     Running   0          75m
kube-flannel   kube-flannel-ds-zk5pb                1/1     Running   0          75m
kube-system    coredns-6d56c8448f-dcbrw             1/1     Running   0          84m
kube-system    coredns-6d56c8448f-ntdsj             1/1     Running   0          84m
kube-system    etcd-k8s-master                      1/1     Running   3          84m
kube-system    kube-apiserver-k8s-master            1/1     Running   3          84m
kube-system    kube-controller-manager-k8s-master   1/1     Running   2          84m
kube-system    kube-proxy-5m7p6                     1/1     Running   0          84m
kube-system    kube-proxy-7h28l                     1/1     Running   0          79m
kube-system    kube-scheduler-k8s-master            1/1     Running   0          84m

 

[root@k8s-master ~]# kubectl describe pods nginx-598f5c449-bdzdm 
Name:         nginx-598f5c449-bdzdm
Namespace:    default
Priority:     0
Node:         k8s-node1/192.168.137.12
Start Time:   Sun, 17 Sep 2023 17:06:08 +0800
Labels:       app=nginx
              pod-template-hash=598f5c449
Annotations:  <none>
Status:       Running
IP:           10.244.1.5
IPs:
  IP:           10.244.1.5
Controlled By:  ReplicaSet/nginx-598f5c449
Containers:
  nginx:
    Container ID:   docker://b7d46bf333041d577700cb4f9b6ac2274be2f189c4e8a07ddd314c1d38c92a74
    Image:          docker.io/nginx
    Image ID:       docker-pullable://docker.io/nginx@sha256:6926dd802f40e5e7257fded83e0d8030039642e4e10c4a98a6478e9c6fe06153
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Sun, 17 Sep 2023 17:06:28 +0800
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-z246f (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             True 
  ContainersReady   True 
  PodScheduled      True 
Volumes:
  default-token-z246f:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-z246f
    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  26m   default-scheduler   Successfully assigned default/nginx-598f5c449-bdzdm to k8s-node1
  Normal  Pulling    26m   kubelet, k8s-node1  Pulling image "docker.io/nginx"
  Normal  Pulled     26m   kubelet, k8s-node1  Successfully pulled image "docker.io/nginx" in 18.897074387s
  Normal  Created    26m   kubelet, k8s-node1  Created container nginx
  Normal  Started    26m   kubelet, k8s-node1  Started container nginx

进入pod

【三】K8S_NameSpace和Pod插图1

查看log 加上f表示实时查看

[root@k8s-master ~]# kubectl logs nginx-598f5c449-bdzdm 
/docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
/docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
/docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
10-listen-on-ipv6-by-default.sh: info: Getting the checksum of /etc/nginx/conf.d/default.conf
10-listen-on-ipv6-by-default.sh: info: Enabled listen on IPv6 in /etc/nginx/conf.d/default.conf
/docker-entrypoint.sh: Sourcing /docker-entrypoint.d/15-local-resolvers.envsh
/docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
/docker-entrypoint.sh: Launching /docker-entrypoint.d/30-tune-worker-processes.sh
/docker-entrypoint.sh: Configuration complete; ready for start up
2023/09/17 09:06:28 [notice] 1#1: using the "epoll" event method
2023/09/17 09:06:28 [notice] 1#1: nginx/1.25.2
2023/09/17 09:06:28 [notice] 1#1: built by gcc 12.2.0 (Debian 12.2.0-14) 
2023/09/17 09:06:28 [notice] 1#1: OS: Linux 3.10.0-1160.el7.x86_64
2023/09/17 09:06:28 [notice] 1#1: getrlimit(RLIMIT_NOFILE): 1048576:1048576
2023/09/17 09:06:28 [notice] 1#1: start worker processes
2023/09/17 09:06:28 [notice] 1#1: start worker process 28
10.244.0.0 - - [17/Sep/2023:09:08:11 +0000] "GET / HTTP/1.1" 200 615 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/101.0.4951.64 Safari/537.36" "-"
10.244.0.0 - - [17/Sep/2023:09:08:11 +0000] "GET /favicon.ico HTTP/1.1" 404 555 "http://192.168.137.11:32371/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/101.0.4951.64 Safari/537.36" "-"
2023/09/17 09:08:11 [error] 28#28: *2 open() "/usr/share/nginx/html/favicon.ico" failed (2: No such file or directory), client: 10.244.0.0, server: localhost, request: "GET /favicon.ico HTTP/1.1", host: "192.168.137.11:32371", referrer: "http://192.168.137.11:32371/"

命令式对象配置: 通过命令配置和配置文件去操作作kubernetes资源

写一个ymal文件:

apiVersion: v1          # API版本号，注意：具有多个，不同的对象可能会使用不同API
kind: Pod               # 对象类型，pod
metadata:               # 元数据
  name: mynginx         # POD名称
 
spec:                   # specification of the resource content(资源内容的规范)
  containers:           # 容器列表
    - name: mynginx     # 容器名称
      image: nginx      # 容器镜像

然后运行yaml文件（提前创建好了命名空间string）

[root@master ~]# vi pod.yaml 
[root@master ~]# kubectl apply -f pod.yaml 
pod/mynginx created
[root@master ~]# kubectl get pod -n string
NAME      READY   STATUS             RESTARTS   AGE
mynginx   1/1     Running            0          27s
 
[root@master ~]# kubectl describe pod mynginx -n string
Name:         mynginx
Namespace:    string
Priority:     0
Node:         node02/172.31.0.2
Start Time:   Mon, 09 Jan 2023 17:10:22 +0800
Labels:       <none>
Annotations:  cni.projectcalico.org/containerID: 5a1eefb7be0f61fc7cceca2c8bfe67e72fe104db89a13b9f58921804278a2904
              cni.projectcalico.org/podIP: 192.168.140.74/32
              cni.projectcalico.org/podIPs: 192.168.140.74/32
Status:       Running
IP:           192.168.140.74
IPs:
  IP:  192.168.140.74
Containers:
  mynginx:
    Container ID:   docker://613b31a4f4736788af136f9187bf78d64ac0f6e0b3960a34087ed481ebed7847
    Image:          nginx
    Image ID:       docker-pullable://nginx@sha256:0d17b565c37bcbd895e9d92315a05c1c3c9a29f762b011a10c54a66cd53c9b31
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Mon, 09 Jan 2023 17:10:23 +0800
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-tv5f7 (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             True 
  ContainersReady   True 
  PodScheduled      True 
Volumes:
  default-token-tv5f7:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-tv5f7
    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  52s   default-scheduler  Successfully assigned string/mynginx to node02
  Normal  Pulling    51s   kubelet            Pulling image "nginx"
  Normal  Pulled     51s   kubelet            Successfully pulled image "nginx" in 429.471972ms
  Normal  Created    51s   kubelet            Created container mynginx
  Normal  Started    51s   kubelet            Started container mynginx
[root@master ~]# kubectl delete -f pod2.yaml 
pod "mynginx" deleted

用bashboard创建pod

【三】K8S_NameSpace和Pod插图2

【三】K8S_NameSpace和Pod插图3

【三】K8S_NameSpace和Pod插图4

一个pod里面运行多个容器

apiVersion: v1          # API版本号，注意：具有多个，不同的对象可能会使用不同API
kind: Pod               # 对象类型，pod
metadata:               # 元数据
  name: mynginx         # POD名称
  namespace: string     # 所属的命名空间
spec:                   # specification of the resource content(资源内容的规范)
  containers:           # 容器列表
    - name: mynginx     # 容器名称
      image: nginx      # 容器镜像
 
    - name: mytomcat
      image: tomcat

运行容器

[root@master ~]# kubectl apply -f pod.yaml 
pod/mynginx created
[root@master ~]# kubectl get pod -n string
NAME      READY   STATUS              RESTARTS   AGE
mynginx   0/2     ContainerCreating   0          23s
[root@master ~]# kubectl get pod -n string -o wide
NAME      READY   STATUS              RESTARTS   AGE   IP       NODE     NOMINATED NODE   READINESS GATES
mynginx   0/2     ContainerCreating   0          33s   <none>   node01   <none>           <none>
[root@master ~]# kubectl get pod mynginx -n string -o wide
NAME      READY   STATUS    RESTARTS   AGE     IP                NODE     NOMINATED NODE   READINESS GATES
mynginx   2/2     Running   0          7m40s   192.168.196.139   node01   <none>           <none>

进入容器查看

[root@master ~]# kubectl exec -it mynginx -n string -- /bin/bash
Defaulting container name to mynginx.
Use 'kubectl describe pod/mynginx -n string' to see all of the containers in this pod.
 
 
root@mynginx:/# curl 127.0.0.1
<!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>
root@mynginx:/# curl 127.0.0.1:8080
<!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/10.0.14</h3></body></html>root
@mynginx:/#

！！注意在一个pod里不能有多个应用都用同一个端口

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